Category The World Around us

Modern medicine uses thousands of different types of drugs, which come from a variety of sources. They can be broadly divided into those that are derived from natural sources such as plants and herbs, and those that are produced artificially from chemicals. A recent development involves genetically engineering certain bacteria to produce a drug for a specific purpose.

Drug, any chemical substance that affects the functioning of living things and the organisms (such as bacteria, fungi, and viruses) that infect them. Pharmacology, the science of drugs, deals with all aspects of drugs in medicine, including their mechanism of action, physical and chemical properties, metabolism, therapeutics, and toxicity. This article focuses on the principles of drug action and includes an overview of the different types of drugs that are used in the treatment and prevention of human dieses. For a discussion of the nonmedical use of drugs, see drug use.

Until the mid-19th century the approach to drug therapeutics was entirely empirical. This thinking changed when the mechanism of drug action began to be analyzed in physiological terms and when some of the first chemical analyses of naturally occurring drugs were performed. The end of the 19th century signaled the growth of the pharmaceutical industry and the production of the first synthetic drugs. Chemical synthesis has become the most important source of therapeutic drugs. A number of therapeutic proteins, including certain antibodies, have been developed through genetic engineering.

Drugs produce harmful as well as beneficial effects, and decisions about when and how to use them therapeutically always involve the balancing of benefits and risks. Drugs approved for human use are divided into those available only with a prescription and those that can be bought freely over the counter. The availability of drugs for medical use is regulated by law.

Drug treatment is the most frequently used type of therapeutic intervention in medicine. Its power and versatility derive from the fact that the human body relies extensively on chemical communication systems to achieve integrated function between billions of separate cells. The body is therefore highly susceptible to the calculated chemical subversion of parts of this communication network that occurs when drugs are administered.

Picture credit: Google

Diseases are caused in many different ways. Infectious diseases are those that can he passed from person to person. They are usually caused by tiny organisms called viruses and bacteria. Influenza (flu) is a disease caused by a virus; typhoid and cholera are caused by bacterial infections. Certain diseases are passed on to children by their parents at conception. These are called hereditary diseases.

Infectious diseases are disorders caused by organisms — such as bacteria, viruses, fungi or parasites. Many organisms live in and on our bodies. They’re normally harmless or even helpful. But under certain conditions, some organisms may cause disease.

Some infectious diseases can be passed from person to person. Some are transmitted by insects or other animals. And you may get others by consuming contaminated food or water or being exposed to organisms in the environment. Signs and symptoms vary depending on the organism causing the infection, but often include fever and fatigue. Mild infections may respond to rest and home remedies, while some life-threatening infections may need hospitalization.

Many infectious diseases, such as measles and chickenpox, can be prevented by vaccines. Frequent and thorough hand-washing also helps protect you from most infectious diseases. Each infectious disease has its own specific signs and symptoms. General signs and symptoms common to a number of infectious diseases include:

• Fever
• Diarrhea
• Fatigue
• Muscle aches
• Coughing

Picture credit: Google

Modern technology allows doctors and other medical specialists to make a more accurate diagnosis of a problem and to treat patients more effectively. Scanners can produce an x-ray or ultrasound image of the whole body, making it possible to identify problems and begin treatment at an early stage. This helps to increase the chance of the patient making a good recovery.

Technology is considered to be the driving force behind improvements in healthcare and, when you look at the rate of change and recent innovations, many find it hard not to agree with that observation. Graduates of health informatics will no doubt agree that technology is impacting many aspects of our lives as breakthroughs in data collection, research and treatments allow medical providers to use new tools and find fresh and innovative ways to practice medicine into the future.

A number of industry analysts have observed that increased accessibility of treatment is one of the most tangible ways that technology has changed healthcare. Health IT opens up many more avenues of exploration and research, which allows experts to make healthcare more driven and effective than it has ever been.

Another key area that has grown and continues to do so is patient care. The use of information technology has made patient care safer and more reliable in most applications. The fact that nurses and doctors who are working on the frontline are now routinely using hand-held computers to record important real-time patient data and then sharing it instantly within their updated medical history is an excellent illustration of the benefits of health IT.

Being able to accumulate lab results, records of vital signs and other critical patient data into one centralized area has transformed the level of care and efficiency a patient can expect to receive when they enter the healthcare system.

An increased level of efficiency in data collection means that a vast online resource of patient history is available to scientists, who are finding new ways to study trends and make medical breakthroughs at a faster rate.

Picture credit: Google

All human beings are likely to suffer from disease or illness at some point in their lives. Medicine is a science that attempts to identify, prevent and treat diseases that affect humans. Diseases are usually treated with drugs or surgery, although preventative treatments, such as vaccinating against diseases before they occur, are an important part of medical science today.

Medicine is the field of health and healing. It includes nurses, doctors, and various specialists. It covers diagnosis, treatment, and prevention of disease, medical research, and many other aspects of health. Medicine aims to promote and maintain health and wellbeing. Conventional modern medicine is sometimes called allopathic medicine. It involves the use of drugs or surgery, often supported by counseling and lifestyle measures. Alternative and complementary types of medicine include acupuncture, homeopathy, herbal medicine, art therapy, traditional Chinese medicine, and many more.

A clinician is a health worker who works directly with patients in a hospital or other healthcare setting. Nurses, doctors, psychotherapists, and other specialists are all clinicians. Not all medical specialists are clinicians. Researchers and laboratory workers are not clinicians because they do not work with patients.

The physician assesses the individual, with the aim of diagnosing, treating, and preventing disease using knowledge learned from training, research, and experiences, and clinical judgment. This area of science seeks ways to prevent and treat diseases that lead to illness or death.

Biomedical scientists use biotechnology techniques to study biological processes and diseases. They aim to develop successful treatments and cures. Biomedical research requires careful experimentation, development, and evaluation. It involves biologists, chemists, doctors, pharmacologists, and others. This field looks at drugs or medicines and how to use them.

Doctors and other health professionals use medications in the medical diagnosis, treatment, cure, and prevention of disease. Surgical procedures are necessary for diagnosing and treating some types of disease, malfomation, and injury. They use instrumental and manual means rather than medication.

A surgeon may carry out a surgical procedure to remove or replace diseased tissue or organs, or they may use surgery to remove tissue for biopsy. Sometimes, they remove unwanted tissue and then send it for diagnosis. Health professionals use a wide range of instruments to diagnose and treat a disease or other condition, to prevent a worsening of symptoms, to replace a damaged part — such as a hip or a knee — and so on. Medical devices range from test tubes to sophisticated scanning machines.

Picture credit: Google

Groups of people can be wiped out when their way of life is threatened by a sudden change of circumstances. One of the best known examples of this happened in the early 16th century, when Spanish conquistadors conquered the Incas and Aztecs of South America. More than 70 million indigenous people were wiped out by diseases such as smallpox and measles, which were brought from Europe by the Spanish. With no history of these diseases, the Incas and Aztecs had few natural defenses against these illnesses.

Europeans people of the Americas between the fifteenth and the seventeenth centuries. Some Europeans ventured out on unknown oceans in order to find trading routes to areas where spices and silver were to be obtained. The first to do this were the Spanish and the Portuguese. They persuaded the Pope to give them the exclusive right to rule over any new regions they might locate. Christopher Columbus, an Italian, sponsored by the rulers of Spain, sailed west in 1492, and thought that the lands he had reached were ‘the Indies’ (India and countries east of India about which he had read in the Travels of Marco Polo). Later exploration indicated that the ‘Indians’ of the ‘New World’ actually belonged to different cultural groups and were not part of Asia. Two types of culture were to be found in the Americas. There were small subsistence economies in the Caribbean region and in Brazil. There were also powerful monarchical systems based on well-developed agriculture and mining. These, like the Aztecs and Mayas of Central America and the Incas of Peru, also had monumental architecture. The exploration and later the settlement of South America were to have disastrous consequences for the native people and their cultures. It also marked the beginning of the slave trade, with Europeans selling slaves from Africa to work in plantations and mines in the Americas.

European conquest of the people of America was accompanied by the ruthless destruction of their manuscripts and monuments. It was only in the late nineteenth century that anthropologists began to study these cultures. Still later, archaeologists found the ruins of these civilisations. The Inca city of Machu Picchu was rediscovered in 1911. Recently, photographs taken from the air have shown traces of many cities now covered by forest. By contrast, we know the European side of the encounters in great detail. The Europeans who went to the Americas kept log-books and diaries of their journeys. There are records left by officials and Jesuit missionaries (see Theme 7). Europeans wrote about their ‘discovery’ of the Americas, and when histories of the countries of America were written, these were in terms of European settlements, with little reference to the local people.

People have been living in North and South America and nearby islands for thousands of years, and many migrations from Asia and from the South Sea Islands have a taken place over time. South America was (and still is, in parts) densely forested and mountainous, and the Amazon, the world’s largest river, flows through miles of dense forest. In Mexico, in Central America, there were densely settled areas of habitation along the coast and in the plains, while elsewhere villages were scattered over forested areas.

One of the great mysteries of the world is the identity of the people who inhabited Easter Island in the South Pacific. The island is famous for the mysterious stone statues found there. It is believed that they were carved by tribes of people who lived there during Neolithic times (more than 1000 years ago). Very little is known about these people, but they are thought to be the ancestors of the people of the islands of Polynesia.

The island’s local Polynesian name is Rapa Nui. The name “Easter Island” came from Dutch explorer Jacob Roggeveen, who was the island’s first European visitor on Easter Sunday in 1722.

Today, Easter Island is believed to be the most remote inhabited island in the world. It’s a special territory of Chile that is famous for its 887 huge statues — called moai — that were created by the early Rapanui people between 1100 and 1680.

Easter Island is a UNESCO World Heritge Site. Much of the island and the moai statues are protected within Rapa Nui National Park. The huge stone moai statues are sometimes referred to as “Easter Island heads.” This nickname is a bit misleading, though, since most of the statues have bodies. Scientists are still unearthing many moai statues that have large portions buried beneath the ground.

Almost all of the statues were carved out of solidified volcanic ash from an extinct volcano called Rano Raraku. The Rapanui carvers used only stone hand chisels to create the magnificent statues. A single moai statue could have taken a team of six men about one year to finish. Experts believe each statue might represent the deceased leader of a particular native family.

Although many statues remain in the quarry at Rano Raraku, many others were transported to other areas of Easter Island. This fact has fascinated explorers for years, because some of the statues weigh over 80 tons. How did the native Rapanui transport these statues up to 11 miles away without wheels or animals?

Experts have come up with many different theories over the years about how the native peoples might have transported these huge statues hundreds of years ago. To date, though, no one knows for sure how many of the statues got to their current locations around the island.

The natural environment is very important to Australian Aborigines. This is because they traditionally believe that the world was created by human, animal and plant ancestors in something called the Dreamtime. The Dreamtime is celebrated and communicated through art, songs, dancing and story-telling.

The Dreamtime is a commonly used term for describing important features of Aboriginal spiritual beliefs and existence. It is not generally well understood by non-indigenous people.

Aboriginals believe that the Dreamtime was way back, at the very beginning. The land and the people were created by the Spirits. They made the rivers, streams, water holes the land, hills, rocks, plants and animals. It is believed that the Spirits gave them their hunting tools and each tribe its land, their totems and their Dreaming.

The Aboriginals believed that the entire world was made by their Ancestors way back in the very beginning of time, the Dreamtime. The Ancestors made everything. The Ancestors made particular sites to show the Aboriginal people which places were to be sacred. The Aboriginals performed ritual ceremonies and customary songs near the sacred sites to please the Ancestral spirits and to keep themselves alive.

Distinct tribes had different philosophies and beliefs about the Ancestors who made the world. Some believed that the Ancestors were animal-spirits.

Others in parts of Arnhem Land in the Northern Territory believed the Ancestors were huge snakes. In other places the spirit who created the world were believed to be the Wanadjina.

Dreamtime is the foundation of Aboriginal religion and culture. It dates back some 65,000 years. It is the story of events that have happened, how the universe came to be, how human beings were created and how their Creator intended for humans to function within the world as they knew it.

Aboriginal people understood the Dreamtime as a beginning that never ended. They held the belief that the Dreamtime is a period on a continuum of past, present and future. The Aborigines learned about their beginnings through their Dreamtime creation folklores that told of the momentous actions of the creators. The myths were the foundation of Aboriginal society and provided certainty about existence. The Australian aborigines believed that the land they occupied was once not in existence like it is today. It was free from form or life, vacuous – empty.

They unquestionably believed that this was the way things once were because the ancestors had said so and they would never doubt their word. It was during what has become known as the Dreamtime, the land, mountains, hills, rivers, plants, life forms both animal and human and sky above were formed by the actions of mysterious and supernatural spirits.

During the Dreamtime the creators made men women and animals, declared the laws of the land and how people were to behave to one another, the customs of food supply and distribution, the rituals of initiation, the ceremonies of death which are required to be performed so that the spirit of the dead travels peacefully to his or her spirit-place, and the laws of marriage. Some Dreaming’s told of the mythical creators disappearing. They believed that the creators disappeared from the sight of mere mortals, but continued to live in secret places.

Some lived in the tribe’s territory in rock crevices, trees and water holes. Others went up into the sky above as heavenly bodies. Others changed into (or perhaps became) natural forces such as wind, rain, thunder and lightning. It is believed that many of the creators continued to live on the land or in the sky above watching over them. These supernatural enigmatic creators were often referred to as men and women who had the ability to change shape into animals and other creatures such as the Rainbow Serpent.

There are also stories of heroes and heroines and Father and Mother figures.

The Dreamtime may be difficult for many of us to understand fully but it is part of which the Aboriginal people are the very essence and reason for being here. It is all encompassing and will forever be at the centre of their existence as a people.

The first people to live in Australia arrived there about 40,000 years ago from Southeast Asia. These people were named “Aborigines” (people who have lived there since early times) by the European settlers who arrived in Australia during the 18th century. Life has been difficult for many Aboriginal Australians, forced to adapt to the settlers’ ways of life. Today, youngsters are being taught about their own rich heritage.

Australia holds some of the earliest archaeological evidence for the presence of modern humans outside Africa, with the earliest sites dated to at least 45,000 years ago, making Australian aboriginals one of the oldest continuous populations outside Africa. It is commonly assumed that following the initial dispersal of people into Sahul (joint Australia-New Guinea landmass) and until the arrival of the Europeans late in the 18th Century, there was no contact between Australia and the rest of the world.

Researcher Irina Pugach and colleagues now analysed genetic variation from across the genome from aboriginal Australians, New Guineans, island Southeast Asians, and Indians. Their findings suggest substantial gene flow from India to Australia 4,230 years ago, i.e. during the Holocene and well before European contact. “Interestingly,” says Pugach, “this date also coincides with many changes in the archaeological record of Australia, which include a sudden change in plant processing and stone tool technologies, with microliths appearing for the first time, and the first appearance of the dingo in the fossil record. Since we detect inflow of genes from India into Australia at around the same time, it is likely that these changes were related to this migration.”

Their analyses also reveal a common origin for populations from Australia, New Guinea and the Mamanwa – a Negrito group from the Philippines – and they estimated that these groups split from each other about 36,000 years ago. Mark Stoneking says: “This finding supports the view that these populations represent the descendants of an early ‘southern route’ migration out of Africa, while other populations in the region arrived later by a separate dispersal.” This also indicates that Australians and New Guineans diverged early in the history of Sahul, and not when the lands were separated by rising sea waters around 8,000 years ago.

The incredibly harsh environment of the Arctic is home to a group of people who settled there around 4000 years ago. They inhabit parts of Siberia, Alaska, Canada and Greenland. Those who live in North America are known as Inuit, which literally means “real men”. Many Inuit continue their traditional lifestyle — hunting for food and furs to sell but being part of both modern and traditional worlds can be hard, especially for young people.

The Inuit people live in the far northern areas of Alaska, Canada, Siberia, and Greenland. They originally made their home along the Alaskan coast, but migrated to other areas. Everything about the lives of the Inuit is influenced by the cold tundra climate in which they live.

The typical materials for making homes such as wood and mud are hard to find in the frozen tundra of the Arctic. The Inuit learned to make warm homes out of snow and ice for the winter. During the summer they would make homes from animal skin stretched over a frame made from driftwood or whalebones. The Inuit word for home is “igloo”.

The Inuit needed thick and warm clothing to survive the cold weather. They used animal skins and furs to stay warm. They made shirts, pants, boots, hats, and big jackets called anoraks from caribou and seal skin. They would line their clothes with furs from animals like polar bears, rabbits, and foxes.

The Inuit people were unable to farm and grow their own food in the harsh desert of the tundra. They mostly lived off of meat from hunting animals. They used harpoons to hunt seals, walruses, and the bowhead whale. They also ate fish and foraged for wild berries. A high percentage of their food was fatty, which gave them energy in the cold weather.

In order to hunt larger prey like walruses and whales, the Inuit hunters would gather in a large group. To hunt a whale, typically at least 20 hunters would gather on a large boat armed with a number of harpoons. They would attach a number of seal-skin balloons filled with air to the harpoons. This way the whale could not dive deep into the water when it was first speared. Each time that the whale would come to the surface for air, the hunters would harpoon it again. Once the whale died, they would tie it to the boat and tow it back to shore.

It would sometimes take a number of men a long time to catch and kill a whale, but it was well worth it. The Inuit used all parts of the whale including the meat, blubber, skin, oil, and bones. A large whale could feed a small community for a year.

Despite the harsh landscape of the Arctic, the Inuit still found ways to travel long distances. On land and ice they used dogsleds called qamutik. They bred strong sled dogs from wolves and dogs to pull the sleds which were made from whale bones and wood. These dogs became the husky dog breed.

On the water, the Inuit used different kinds of boats for different activities. For hunting they used small single-passenger boats called kayaks. They also built larger, faster boats called umiaqs that were used for transporting people, dogs, and goods.

Picture Credit : Google

Around 20,000 years ago, the first settlers of North America arrived from Asia. They were able to travel over land, because at the time, the two continents were joined together. These early settlers gradually formed different tribes and spread them-selves throughout the whole country. When the first Europeans arrived during the 15th century, they thought they had landed in Asia, and called the Native Americans “Indians”. The relationship between the Indians and the new settlers was difficult, and many battles were fought.

Many thousands of years before Christopher Columbus’ ships landed in the Bahamas, a different group of people discovered America: the nomadic ancestors of modern Native Americans who hiked over a “land bridge” from Asia to what is now Alaska more than 12,000 years ago. In fact, by the time European adventurers arrived in the 15th century A.D., scholars estimate that more than 50 million people were already living in the Americas. Of these, some 10 million lived in the area that would become the United States. As time passed, these migrants and their descendants pushed south and east, adapting as they went. In order to keep track of these diverse groups, anthropologists and geographers have divided them into “culture areas,” or rough groupings of contiguous peoples who shared similar habitats and characteristics. Most scholars break North America—excluding present-day Mexico—into 10 separate culture areas: the Arctic, the Subarctic, the Northeast, the Southeast, the Plains, the Southwest, the Great Basin, California, the Northwest Coast and the Plateau.

The Arctic culture area, a cold, flat, treeless region (actually a frozen desert) near the Arctic Circle in present-day Alaska, Canada and Greenland, was home to the Inuit and the Aleut. Both groups spoke, and continue to speak, dialects descended from what scholars call the Eskimo-Aleut language family. Because it is such an inhospitable landscape, the Arctic’s population was comparatively small and scattered. Some of its peoples, especially the Inuit in the northern part of the region, were nomads, following seals, polar bears and other game as they migrated across the tundra. In the southern part of the region, the Aleut were a bit more settled, living in small fishing villages along the shore.

Picture Credit : Google

The human race is made up of many different nationalities and groups of people. Indigenous people are those who are native to a certain area. The term is often used to describe the original inhabitants of areas that are now populated by people from other parts of the world.

Indigenous peoples are inheritors and practitioners of unique cultures and ways of relating to people and the environment. They have retained social, cultural, economic and political characteristics that are distinct from those of the dominant societies in which they live. Despite their cultural differences, indigenous peoples from around the world share common problems related to the protection of their rights as distinct peoples.

Indigenous peoples have sought recognition of their identities, way of life and their right to traditional lands, territories and natural resources for years, yet throughout history; their rights have always been violated. Indigenous peoples today, are arguably among the most disadvantaged and vulnerable groups of people in the world. The international community now recognizes that special measures are required to protect their rights and maintain their distinct cultures and way of life. Find below a short history of the indigenous struggle in the international stage.

While making up less than five percent of the world’s population, indigenous people account for 15 percent of the poorest. They’re more likely to suffer from malnutrition, and often lack adequate social protection and economic resources. The international community recognizes that special measures are required to protect their rights and maintain their distinct cultures.

The life expectancy of indigenous people is as much as 20 years lower than that of their non-indigenous counterparts. Often lacking adequate healthcare and information, they are more likely to get diseases such as malaria, tuberculosis, HIV and AIDS.

More than one in three indigenous women are sexually assaulted during their lifetime, and they also have higher rates of maternal mortality, teen pregnancy, and sexually transmitted diseases. The Declaration on the Right of Indigenous People draws attention to the needs and rights of indigenous women and calls for action to protect them from violence. Indigenous peoples are inheritors and practitioners of unique cultures and ways of living.?Nearly 70 million indigenous women and men depend on forests for their livelihoods, and many more are farmers, hunter gatherers or pastoralists.

These communities thrive by living in harmony with their surroundings. Research shows that where indigenous groups have control of the land, forests and biodiversity flourishes. Indigenous communities’ contribution to fighting climate change are far greater than previously thought. Their forestlands store at least one quarter of all above-ground tropical forest carbon – about 55 trillion metric tonnes. This is?equivalent to four times the total global carbon emissions in 2014. Given that data isn’t available for all the lands native communities manage around the world, the actual impact is far greater.

Picture Credit : Google

The most common reason that people move to other countries is to seek work. Modem North America was founded through mass immigration — its population grew from 31 to 92 million between 1860 and 1910. Some people may leave their home country because of war, or for political or religious reasons. These people are known as refugees.

Migration involves people crossing state boundaries and staying in the host state for a minimum length of time. Migration occurs for many reasons. The overwhelming majority of people migrate internationally for reasons related to work, family and study – involving migration processes that largely occur without fundamentally challenging either migrants or the countries they enter. In contrast, other people leave their homes and countries for a range of compelling and sometimes tragic reasons, such as conflict, persecution and disaster. While those who have been displaced, such as refugees and internally displaced persons (IDPs), comprise a relatively small percentage of all migrants, they are often the most in need of assistance and support. The terms “international migration” and “international migrant” are different but often conflated and used (incorrectly) interchangeably. International migration is the process of moving from one country to another. It involves action. In contrast, a “migrant” is a person described as such for one or more reasons, depending on the context. While in many cases, migrants do undertake some form of migration, this is not always the case. In some situations, people who have never undertaken migration may be referred to as migrants – children of people born overseas, for example, are commonly called second or third-generation migrants. While there are several different potential systems for categorizing international migrants, one system organizes them into nine groups: temporary labour migrants; irregular, illegal, or undocumented migrants; highly skilled and business migrants; refugees; asylum seeker; forced migration; family members; return migrants; and long-term, low-skilled migrants. These migrants can also be divided into two large groups, permanent and temporary. Permanent migrants intend to establish their permanent residence in a new country and possibly obtain that country’s citizenship. Temporary migrants intend only to stay for a limited periods of time; perhaps until the end of a particular program of study or for the duration of their work contract or a certain work season. Both types of migrants have a significant effect on the economies and societies of the chosen destination country and the country of origin.

Similarly, the countries which receive these migrants are often grouped into four categories: traditional settlement countries, European countries which encouraged labour migration after World War II, European countries which receive a significant portion of their immigrant populations from their former colonies, and countries which formerly were points of emigration but have recently emerged as immigrant destinations.

Picture Credit : Google

In the modern world, more and more people live in towns and cities. This is mainly because of employment opportunities — there are generally more jobs to be found in urban areas — but also because modern building methods allow more people to live in a smaller area. Roughly half of the world’s population lives in cities, and this proportion is expected to increase.

Urbanization is something that eventually happens in any developing country, as the population condenses into smaller cities and towns. Agriculture begins to decline, and industrialization fuels the move from rural areas to urban ones.

There are some positives and negatives to urbanization. When done correctly, urbanization means a greater variety of opportunity for residents. If it gets out of hand, though, crime and poverty start to rise uncontrollably.

Urbanization is when people move from rural farmland to cities and towns. Rural areas are more densely packed and offer greater opportunities to their residents in the form of higher paying jobs and a larger variety of job opportunities.

Most developing countries experience the process of urbanization, especially once they start becoming industrialized. Cities and towns become hubs of trade and culture, and more people start moving out of the country to gain access to some of these social and financial benefits.

Urbanization is a natural part of developing society, but it has its downside as well. As populations in cities and towns rise, they expand and eventually invade rural areas. We need to strike a balance with urbanization if we want to flourish as a society. Urbanization is inevitable as a country’s production moves away from agriculture and towards industry. People begin to move to the cities for better access to employment and resources.

Multiple factors contribute to urbanization, and many of them are positive. People seek the best opportunity to provide for themselves and their families, and urban environments are often the answer.

Urban areas have more jobs to offer and can lure people out of rural areas with the promise of a better life and a higher-paying salary. People find more jobs in virtually every industry while looking in cities and towns than they do searching rural locations. There are more people in urban areas, which mean there is more demand. The increased demand opens the door to employment opportunities for a lot of people who can’t find a job in their rural hometown.

In developing countries, employment opportunities often open rapidly through the process of industrialization. Every developing country goes through a period of industrialization, where jobs move from agriculture to production. People begin to move to cities and towns more frequently, adding to the urbanization of that country.

Picture Credit : Google

The average age of a population varies from country to country. In the more developed parts of the world, the population is generally older. High standards of healthcare allow people to live longer, and families tend to have fewer children. In poorer countries, life expectancy is shorter and many babies die at birth. As a result, families have more children, which mean that the population is generally younger.

People worldwide are living longer. Today, for the first time in history, most people can expect to live into their sixties and beyond. By 2050, the world’s population aged 60 years and older is expected to total 2 billion, up from 900 million in 2015. Today, 125 million people are aged 80 years or older. By 2050, there will be almost this many (120 million) living in China alone, and 434 million people in this age group worldwide. By 2050, 80% of all older people will live in low- and middle-income countries.

The pace of population ageing around the world is also increasing dramatically. France had almost 150 years to adapt to a change from 10% to 20% in the proportion of the population that was older than 60 years .However, places such as Brazil, China and India will have slightly more than 20 years to make the same adaptation.

While this shift in distribution of a country’s population towards older ages – known as population ageing – started in high-income countries (for example in Japan 30% of the population are already over 60 years old), it is now low- and middle-income countries that are experiencing the greatest change. By the middle of the century many countries for e.g. Chile, China, the Islamic Republic of Iran and the Russian Federation will have a similar proportion of older people to Japan.

A longer life brings with it opportunities, not only for older people and their families, but also for societies as a whole. Additional years provide the chance to pursue new activities such as further education, a new career or pursuing a long neglected passion. Older people also contribute in many ways to their families and communities. Yet the extent of these opportunities and contributions depends heavily on one factor: health.

There is, however, little evidence to suggest that older people today are experiencing their later years in better health than their parents. While rates of severe disability have declined in high-income countries over the past 30 years, there has been no significant change in mild to moderate disability over the same period.

At the biological level, ageing results from the impact of the accumulation of a wide variety of molecular and cellular damage over time. This leads to a gradual decrease in physical and mental capacity, a growing risk of disease, and ultimately, death. But these changes are neither linear nor consistent, and they are only loosely associated with a person’s age in years. While some 70 year-olds enjoy extremely good health and functioning, other 70 year-olds are frail and require significant help from others.

Beyond biological changes, ageing is also associated with other life transitions such as retirement, relocation to more appropriate housing, and the death of friends and partners. In developing a public-health response to ageing, it is important not just to consider approaches that ameliorate the losses associated with older age, but also those that may reinforce recovery, adaptation and psychosocial growth.

Common conditions in older age include hearing loss, cataracts and refractive errors, back and neck pain and osteoarthritis, chronic obstructive pulmonary disease, diabetes, depression, and dementia. Furthermore, as people age, they are more likely to experience several conditions at the same time.

Older age is also characterized by the emergence of several complex health states that tend to occur only later in life and that do not fall into discrete disease categories. These are commonly called geriatric syndromes. They are often the consequence of multiple underlying factors and include frailty, urinary incontinence, falls, delirium and pressure ulcers.

Geriatric syndromes appear to be better predictors of death than the presence or number of specific diseases. Yet outside of countries that have developed geriatric medicine as a specialty, they are often overlooked in traditionally structured health services and in epidemiological research.

Picture Credit : Google

China has been the world’s most populated country for some time. This vast country is home to over one billion people around one sixth of the world’s total. In an effort to control the growth in numbers of people there, the government has encouraged families to have only one child.

India is set to overtake China as the world’s most populous country in less than a decade, according to a new United Nations report.

China and India currently account for about 37% of the entire global population of roughly 7.7 billion, with China currently home to about 1.4 billion people and India to 1.3 billion. But by 2027, India will have more people than China, according to the UN’s 2019 World Population Prospects report released Monday, and by 2050 the gap is expected to have widened even further. “Between 2019 and 2050, 55 countries or areas are expected to see their populations decrease by at least 1%,” the report said, mostly due to low-levels of fertility and in some cases, high numbers of emigration.

“In the largest of these, China, the population is projected to shrink by 31.4 million, or 2.2 per cent.” That would put China’s population at 1.1 billion, fewer than the 1.5 billion forecast for India.

By 2050, the report predicts the planet’s entire population will be 9.7 billion people, a staggering rise in just one century. Five years after the founding of the UN in 1950, the global population was a mere 2.6 billion people. The UN compiles the report using demographic trends and relevant patterns in human fertility, mortality and migration. The aim is to provide governments with information as they work towards the UN’s 2030 Sustainable Development Goals.

China has been attempting to preemptively tackle a looming population decline for years. With the country’s population rapidly aging and birth rates falling, Beijing even reversed its infamous One Child policy to encourage couples to have more children.

But with an increasingly urban population facing rising costs of living, attempts to push up the birth rate have failed.

Besides India overtaking China, the UN report said Nigeria will be the third most populous country by 2050 with an estimated 733 million people, overtaking the United States, which will fall to fourth place with a population of 434 million. Pakistan will remain the world’s fifth largest country in terms of population.

“Many of the fastest growing populations are in the poorest countries, where population growth brings additional challenges”, said Liu Zhenmin, United Nations Under-Secretary-General for Economic and Social Affairs (DESA), in a statement.

More than half of the predicted global population by 2050 will be clustered in just nine countries, the report said: India, Nigeria, Pakistan, the Democratic Republic of Congo, Ethiopia, Tanzania, Indonesia, Egypt and the United States. Large global trends include decreasing populations, unprecedentedly large, aging populations due to rising life expectancy, and a narrowing discrepancy between rich and poor countries.

Picture Credit : Google

Around a thousand years ago, the world’s population began to increase dramatically, with the sharpest increase occurring during the 20th century. In the year 2000, the world’s population reached six billion, and its growth shows no sign of stopping. Many people fear that an ever-increasing population will lead to serious problems with food supply and overcrowding.

There has been tremendous growth in the size of the world’s population in the last half century. Global population was around 3 billion in 1960. By 1987, in less than three decades, it had surpassed 5 billion and there were around 7.6 billion people in the world in 2018.

This growth varies greatly across regions. Since 1960, the largest relative growth has taken place in Sub-Saharan Africa where the population expanded from 227 million in 1960 to more than 1 billion in 2018—a nearly fivefold increase. The second largest growth over the period can be seen in Middle East and North Africa, where the population increased more than 4 times, from 105 million to 449 million.

It is projected that the world’s population will continue to grow and will reach nearly 10 billion by 2050. While in other regions growth will slow significantly, in Sub-Saharan Africa, the population is projected to double by 2050, an expansion of nearly 10 times relative to 1960, from 227 million to 2.2 billion.

As a result, the share of Sub-Saharan Africa in the world’s population is projected to grow as well. In 1960, the share of the region was just 7 percent, but this has increased to 14 percent in 2018, and is projected to reach 23 percent by 2050. Globally, almost 1 in 4 people will be Sub-Saharan African in 2050, whereas the ratio was 1 in 13 in 1960.

This is largely due to continuously higher fertility rates in Sub-Saharan Africa compared to the rest of the world. Today, on average, women there have 4.8 children per woman, compared with less than 3 children per woman worldwide, and the fertility in Sub-Saharan Africa is projected to remain substantially higher than in any other region for the next few decades.

The size of the world’s population is the result of fertility and mortality in the past years – births and deaths. In fact, there is a strong correlation between fertility and mortality. Women tend to have more children where children are more likely to die, and bear fewer children where their child’s risk of dying is lower. In all regions, both mortality and fertility are lowering, but in Sub-Saharan Africa both fertility and mortality are higher than in other parts of the world, and fertility tends to be higher for a given level of child mortality, when compared to other regions, such as South Asia.

Picture Credit : Google

Given the right conditions, CFCs can also damage the ozone layer. The CFCs combine with very cool air, producing chlorine — a substance that eats away at ozone. Ozone loss is worst at the area above the South Pole, where a complete “hole” was confirmed in 1985. Reduced ozone levels mean that a greater amount of the Sun’s harmful ultraviolet rays will reach the Earth’s surface, affecting human and animal health, as well as damaging food crops.

The ozone hole is not technically a “hole” where no ozone is present, but is actually a region of exceptionally depleted ozone in the stratosphere over the Antarctic that happens at the beginning of Southern Hemisphere spring (August–October). Satellite instruments provide us with daily images of ozone over the Antarctic region. The ozone hole image below shows the very low values (blue and purple colored area) centered over Antarctica on 4 October 2004. From the historical record we know that total column ozone values of less than 220 Dobson Units were not observed prior to 1979. From an aircraft field mission over Antarctica we also know that a total column ozone level of less than 220 Dobson Units is a result of catalyzed ozone loss from chlorine and bromine compounds. For these reasons, we use 220 Dobson Units as the boundary of the region representing ozone loss. Using the daily snapshots of total column ozone, we can calculate the area on the Earth that is enclosed by a line with values of 220 Dobson Units (the white line in the figure below).

Many people have heard that the ozone hole is caused by chemicals called CFCs, short for chlorofluorocarbons. CFCs escape into the atmosphere from refrigeration and propellant devices and processes. In the lower atmosphere, they are so stable that they persist for years, even decades. This long lifetime allows some of the CFCs to eventually reach the stratosphere. In the stratosphere, ultraviolet light breaks the bond holding chlorine atoms (Cl) to the CFC molecule. A free chlorine atom goes on to participate in a series of chemical reactions that both destroy ozone and return the free chlorine atom to the atmosphere unchanged, where it can destroy more and more ozone molecules. For those who know the story of CFCs and ozone, that is the part of the tale that is probably familiar.

The part of the story that fewer people know is that while the chlorine atoms freed from CFCs do ultimately destroy ozone, the destruction doesn’t happen immediately. Most of the roaming chlorine that gets separated from CFCs actually becomes part of two chemicals that—under-normal atmospheric conditions—are so stable that scientists consider them to be long-term reservoirs for chlorine.

Under normal atmospheric conditions, the two chemicals that store most atmospheric chlorine (hydrochloric acid, and chlorine nitrate) are stable. But in the long months of polar darkness over Antarctica in the winter, atmospheric conditions are unusual. An endlessly circling whirlpool of stratospheric winds called the polar vortex isolates the air in the center. Because it is completely dark, the air in the vortex gets so cold that clouds form, even though the Antarctic air is extremely thin and dry. Chemical reactions take place that could not take place anywhere else in the atmosphere. These unusual reactions can occur only on the surface of polar stratospheric cloud particles, which may be water, ice, or nitric acid, depending on the temperature.

Picture Credit : Google

CFCs (chlorofluorocarbons) are another example of greenhouse gases. They are found in aerosol sprays, refrigeration and air-conditioning systems, and certain types of foam packaging. Awareness of the damage caused by CFCs has meant that some products are labelled as “CFC Free”.

Chlorofluorocarbon (CFC) is an organic compound that contains carbon, chlorine, and fluorine, produced as a volatile derivative of methane and ethane. A common subclass is the hydrochlorofluorocarbons (HCFCs), which contain hydrogen, as well. Freon is DuPont’s brand name for CFCs, HCFCs and related compounds. Other commercial names from around the world are Algofrene, Arcton, Asahiflon, Daiflon, Eskimo, FCC, Flon, Flugene, Forane, Fridohna, Frigen, Frigedohn, Genetron, Isceon, Isotron, Kaiser, Kaltron, Khladon, Ledon, Racon, and Ucon. The most common representative is dichlorodifluoromethane (R-12 or Freon-12).

Chlorofluorocarbons (CFCs) are a family of chemical compounds developed back in the 1930’s as safe, non-toxic, non-flammable alternative to dangerous substances like ammonia for purposes of refrigeration and spray can propellants. Their usage grew enormously over the years. One of the elements that make up CFCs is chlorine. Very little chlorine exists naturally in the atmosphere. But it turns out that CFCs are an excellent way of introducing chlorine into the ozone layer. The ultraviolet radiation at this altitude breaks down CFCs, freeing the chlorine. Under the proper conditions, this chlorine has the potential to destroy large amounts of ozone. This has indeed been observed, especially over Antarctica. As a consequence, levels of genetically harmful ultraviolet radiation have increased.

Work on alternatives for chlorofluorocarbons in refrigerants began in the late 1970s after the first warnings of damage to stratospheric ozone were published. The hydrochlorofluorocarbons (HCFCs) are less stable in the lower atmosphere, enabling them to break down before reaching the ozone layer. Nevertheless, a significant fraction of the HCFCs do break down in the stratosphere and they have contributed to more chlorine buildup there than originally predicted. Later alternatives lacking the chlorine, the hydrofluorocarbons (HFCs) have an even shorter lifetimes in the lower atmosphere. One of these compounds, HFC-134a, is now used in place of CFC-12 in automobile air conditioners. Hydrocarbon refrigerants (a propane/isobutane blend) are also used extensively in mobile air conditioning systems in Australia, the USA and many other countries, as they have excellent thermodynamic properties and perform particularly well in high ambient temperatures. One of the natural refrigerants (along with Ammonia and Carbon Dioxide), hydrocarbons have negligible environmental impacts and are also used worldwide in domestic and commercial refrigeration applications, and are becoming available in new split system air conditioners

Picture Credit : Google

The “greenhouse effect” is a natural process through which gases in the atmosphere trap the Sun’s heat and warm the Earth. Industrial activities such as burning fossil fuels have added to the levels of carbon dioxide and other “greenhouse gases” in the atmosphere. This has increased the greenhouse effect, causing the Earth to get hotter than it would have done naturally.

Glaciers are melting, sea levels are rising, cloud forests are dying, and wildlife is scrambling to keep pace. It has become clear that humans have caused most of the past century’s warming by releasing heat-trapping gases as we power our modern lives. Called greenhouse gases, their levels are higher now than at any time in the last 8000,000 years.

We often call the result global warming, but it is causing a set of changes to the Earth’s climate, or long-term weather patterns, that varies from place to place. While many people think of global warming and climate change as synonyms, scientists use “climate change” when describing the complex shifts now affecting our planet’s weather and climate systems—in part because some areas actually get cooler in the short term.

Climate change encompasses not only rising average temperatures but also extreme weather events, shifting wildlife populations and habitats, rising seas, and a range of other impacts. All of those changes are emerging as human continue to add heat-trapping greenhouses gases to the atmosphere, changing the rhythms of climate that all living things have come to rely on.

What will we do—what can we do—to slow this human-caused warming? How will we cope with the changes we’ve already set into motion? While we struggle to figure it all out, the fate of the Earth as we know it—coasts, forests, farms, and snow-capped mountains—hangs in the balance.

Sunlight shines onto the Earth’s surface, where the energy is absorbed and then radiate back into the atmosphere as heat. In the atmosphere, greenhouse gas molecules trap some of the heat, and the rest escapes into space. The more greenhouse gases concentrate in the atmosphere, the more heat gets locked up in the molecules.

Scientists have known about the greenhouse effect since 1824, when Joseph fourier calculated that the Earth would be much colder if it had no atmosphere. This natural greenhouse effect is what keeps the Earth’s climate livable. Without it, the Earth’s surface would be an average of about 60 degrees Fahrenheit (33 degrees Celsius) cooler.

Levels of greenhouse gases have gone up and down over the Earth’s history, but they had been fairly constant for the past few thousand years. Global average temperatures had also stayed fairly constant over that time—until the past 150 years. Through the burning of fossil fuels and other activities that have emitted large amounts of greenhouse gases, particularly over the past few decades, humans are now enhancing the greenhouse effect and warming Earth significantly, and in ways that promise many effects, scientists warn.

Picture Credit : Google

Ozone is a very important gas in the Earth’s atmosphere. It screens out some of the harmful ultraviolet rays that come from the Sun. The ozone layer is a very fine layer of the gas that surrounds the Earth at a height varying between 15 and 50km (between 9 and 30 miles).

The ozone layer is one layer of the stratosphere, the second layer of the Earth’s atmosphere. The stratosphere is the mass of protective gases clinging to our planet.

The stratosphere gets its name because it is stratified, or layered: as elevation increases, the stratosphere gets warmer. The stratosphere increases in warmth with elevation because ozone gases in the upper layers absorb intense ultraviolet radiation from the sun.

Ozone is only a trace gas in the atmosphere—only about 3 molecules for every 10 million molecules of air. But it does a very important job. Like a sponge, the ozone layer absorbs bits of radiation hitting Earth from the sun. Even though we need some of the sun’s radiation to live, too much of it can damage living things. The ozone layer acts as a shield for life on Earth.

Ozone is good at trapping a type of radiation called ultraviolet radiation, or UV light, which can penetrate organisms’ protective layers, like skin, damaging DNA molecules in plants and animals. There are two major types of UV light: UVB and UVA.

UVB is the cause of skin conditions like sunburns, and cancers like basal cell carcinoma and squamous cell carcinoma. People used to think that UVA light, the radiation used in tanning beds, is harmless because it doesn’t cause burns. However, scientists now know that UVA light is even more harmful than UVB, penetrating more deeply and causing a deadly skin cancer, melanoma, and premature aging. The ozone layer, our Earth’s sunscreen, absorbs about 98 percent of this devastating UV light.

The ozone layer is getting thinner. Chemicals called chlorofluorocarbons (CFCs) are a reason we have a thinning ozone layer. A chlorofluorocarbon (CFC) is a molecule that contains the elements carbon, chlorine, and fluorine. CFCs are everywhere, mostly in refrigerants and plastic products. Businesses and consumers use them because they’re inexpensive, they don’t catch fire easily, and they don’t usually poison living things. But the CFCs start eating away at the ozone layer once they get blown into the stratosphere.

Ozone molecules, which are simply made of three joined oxygen atoms, are always being destroyed and reformed naturally. But CFCs in the air make it very difficult for ozone to reform once it’s broken apart. The ozone layer, which only makes up 0.00006 percent of Earth’s atmosphere, is getting thinner and thinner all the time.

“Ozone holes” are popular names for areas of damage to the ozone layer. This is inaccurate. Ozone layer damage is more like a really thin patch than a hole. The ozone layer is thinnest near the poles.

In the 1970s, people all over the world started realizing that the ozone layer was getting thinner and that this was a bad thing. Many governments and businesses agreed that some chemicals, like aerosol cans, should be outlawed. There are fewer aerosol cans produced today. The ozone layer has slowly recovered as people, businesses, and governments work to control such pollution.

Picture Credit : Google

The earth is continually recycling the essential ingredients for life — carbon, oxygen, nitrogen and water. All plants and animals play their part in this recycling process.

Energy flows directionally through ecosystems, entering as sunlight (or inorganic molecules for chemoautotrophs) and leaving as heat during the many transfers between trophic levels. However, the matter that makes up living organisms is conserved and recycled. The six most common elements associated with organic molecules (carbon, nitrogen, hydrogen, oxygen, phosphorus, and sulfur) take a variety of chemical forms and may exist for long periods in the atmosphere, on land, in water, or beneath the earth’s surface. Geologic processes, such as weathering, erosion, water drainage, and the movement of the continental plates, all play a role in this recycling of materials. Because geology and chemistry have major roles in the study of this process, the recycling of inorganic matter between living organisms and their environment is called a biogeochemical cycle.

The components of organic molecules are constantly being stored and recycled as part of their biogeochemical cycle. Water, which contains hydrogen and oxygen, is essential to all living processes. The hydrosphere is the area of the earth where water movement and storage occurs. Water can be liquid on the surface and beneath the surface or frozen (rivers, lakes, oceans, groundwater, polar ice caps, and glaciers) or exist as water vapor in the atmosphere. Carbon, found in all organic macromolecules, is an important constituent of fossil fuels. Nitrogen, a major component of our nucleic acids and proteins, is critical to human agriculture. Phosphorus, a major component of nucleic acid (along with nitrogen), is one of the main ingredients in artificial fertilizers used in agriculture and their associated environmental impacts on our surface water. Sulfur, critical to the 3–D folding of proteins (as in disulfide binding), is released into the atmosphere by the burning of fossil fuels, such as coal.

The cycling of all of these elements is interconnected. For example, the movement of water is critical for the leaching of nitrogen and phosphate into rivers, lakes, and oceans. Furthermore, the ocean itself is a major reservoir for carbon. Thus, mineral nutrients are cycled, either rapidly or slowly, through the entire biosphere, from one living organism to another, and between the biotic and abiotic world.

Water is the basis of all living processes. More than half of the human body is made up of water, while human cells are more than 70 percent water. Thus, most land animals need a supply of fresh water to survive. However, when examining the stores of water on earth, 97.5 percent of it is non-potable salt water. Of the remaining water, 99 percent is locked underground as water or as ice. Thus, less than 1 percent of fresh water is easily accessible from lakes and rivers. Many living things, such as plants, animals, and fungi, are dependent on the small amount of fresh surface water supply, a lack of which can have massive effects on ecosystem dynamics. Humans, of course, have developed technologies to increase water availability, such as digging wells to harvest groundwater, storing rainwater, and using desalination to obtain drinkable water from the ocean. Although this pursuit of drinkable water has been ongoing throughout human history, the supply of fresh water is still a major issue in modern times.

The water cycle is driven by the sun’s energy as it warms the oceans and other surface waters. This leads to the evaporation (water to water vapor) of liquid surface water and the sublimation (ice to water vapor) of frozen water, which deposits large amounts of water vapor into the atmosphere. Over time, this water vapor condenses into clouds as liquid or frozen droplets, which is eventually followed by precipitation (rain or snow), returning water to the earth’s surface. Rain eventually percolates into the ground, where it may evaporate again (if it is near the surface), flow beneath the surface, or be stored for long periods. More easily observed is surface runoff: the flow of fresh water either from rain or melting ice. Runoff can then make its way through streams and lakes to the oceans or flow directly to the oceans themselves. Rain and surface runoff are major ways in which minerals, including carbon, nitrogen, phosphorus, and sulfur, are cycled from land to water.

Carbon, the second most abundant element in living organisms, is present in all organic molecules. Its role in the structure of macromolecules is of primary importance to living organisms. Carbon compounds contain especially- high forms of energy, which humans use as fuel. Since the 1800s (the beginning of the Industrial Revolution), the number of countries using massive amounts of fossil fuels increased, which raised the levels of carbon dioxide in the atmosphere. This increase in carbon dioxide has been associated with climate change and other disturbances of the earth’s ecosystems. It is a major environmental concern worldwide.

The carbon cycle is most easily studied as two interconnected sub-cycles: one dealing with rapid carbon exchange among living organisms and the other dealing with the long-term cycling of carbon through geologic processes.

Picture Credit : Google

An ecosystem is any area that can support different living things, and as such can be almost any size. A droplet of rain may contain bacteria and other microscopic living things that live off one another, and could therefore be described as an ecosystem.

An ecosystem is a geographic area where plants, animals, and other organisms, as well as weather and landscape, work together to form a bubble of life. Ecosystems contain biotic or living, parts, as well as abiotic factors, or nonliving parts. Biotic factors include plants, animals, and other organisms. Abiotic factors include rocks, temperature, and humidity.

Every factor in an ecosystem depends on every other factor, either directly or indirectly. A change in the temperature of an ecosystem will often affect what plants will grow there, for instance. Animals that depend on plants for food and shelter will have to adapt to the changes, move to another ecosystem, or perish.

Ecosystems can be very large or very small. Tide pools, the ponds left by the ocean as the tide goes out, are complete, tiny ecosystems. Tide pools contain seaweed, a kind of algae, which uses photosynthesis to create food. Herbivores such as abalone eat the seaweed. Carnivores such as sea stars eat other animals in the tide pool, such as clams or mussels. Tide pools depend on the changing level of ocean water. Some organisms, such as seaweed, thrive in an aquatic environment, when the tide is in and the pool is full. Other organisms, such as hermit crabs, cannot live underwater and depend on the shallow pools left by low tides. In this way, the biotic parts of the ecosystem depend on abiotic factors.

The whole surface of Earth is a series of connected ecosystems. Ecosystems are often connected in a larger biome. Biomes are large sections of land, sea, or atmosphere. Forests, ponds, reefs, and tundra are all types of biomes, for example. They’re organized very generally, based on the types of plants and animals that live in them. Within each forest, each pond, each reef, or each section of tundra, you’ll find many different ecosystems.

The biome of the Sahara Desert, for instance, includes a wide variety of ecosystems. The arid climate and hot weather characterize the biome. Within the Sahara are oasis ecosystems, which have date palm trees, freshwater, and animals such as crocodiles. The Sahara also has dune ecosystems, with the changing landscape determined by the wind. Organisms in these ecosystems, such as snakes or scorpions, must be able to survive in sand dunes for long periods of time. The Sahara even includes a marine environment, where the Atlantic Ocean creates cool fogs on the Northwest African coast. Shrubs and animals that feed on small trees, such as goats, live in this Sahara ecosystem.

Even similar-sounding biomes could have completely different ecosystems. The biome of the Sahara Desert, for instance, is very different from the biome of the Gobi Desert in Mongolia and China. The Gobi is a cold desert, with frequent snowfall and freezing temperatures. Unlike the Sahara, the Gobi has ecosystems based not in sand, but kilometers of bare rock. Some grasses are able to grow in the cold, dry climate. As a result, these Gobi ecosystems have grazing animals such as gazelles and even takhi, an endangered species of wild horse.

Even the cold desert ecosystems of the Gobi are distinct from the freezing desert ecosystems of Antarctica. Antarcticas thick ice sheet covers a continent made almost entirely of dry, bare rock. Only a few mosses grow in this desert ecosystem, supporting only a few birds, such as skuas.

Picture Credit : Google

The biosphere is the part of the Earth in which life exists. It covers an area that stretches from the very bottom of the oceans to some way above the surface of the Earth.

The biosphere is made up of the parts of Earth where life exists. The biosphere extends from the deepest root systems of trees, to the dark environment of ocean trenches, to lush rain forests and high mountaintops.

Scientists describe the Earth in terms of spheres. The solid surface layer of the Earth is the lithosphere. The atmosphere is the layer of air that stretches above the lithosphere. The Earth’s water—on the surface, in the ground, and in the air—makes up the hydrosphere.

Since life exists on the ground, in the air, and in the water, the biosphere overlaps all these spheres. Although the biosphere measures about 20 kilometers (12 miles) from top to bottom, almost all life exists between about 500 meters (1,640 feet) below the ocean’s surface to about 6 kilometers (3.75 miles) above sea level.

The biosphere has existed for about 3.5 billion years. The biosphere’s earliest life-forms, called prokaryotes, survived without oxygen. Ancient prokaryotes included single-celled organisms such as bacteria and archaea.

Some prokaryotes developed a unique chemical process. They were able to use sunlight to make simple sugars and oxygen out of water and carbon dioxide, a process called photosynthesis. These photosynthetic organisms were so plentiful that they changed the biosphere. Over a long period of time, the atmosphere developed a mix of oxygen and other gases that could sustain new forms of life.

The addition of oxygen to the biosphere allowed more complex life-forms to evolve. Millions of different plants and other photosynthetic species developed. Animals, which consume plants (and other animals) evolved. Bacteria and other organisms evolved to decompose, or break down, dead animals and plants.

The biosphere benefits from this food web. The remains of dead plants and animals release nutrients into the soil and ocean. These nutrients are re-absorbed by growing plants. This exchange of food and energy makes the biosphere a self-supporting and self-regulating system.

The biosphere is sometimes thought of as one large ecosystem—a complex community of living and nonliving things functioning as a single unit. More often, however, the biosphere is described as having many ecosystems.

Picture Credit : Google

Scientists who study the relationships between different forms of life on Earth are called ecologists. They divide up the bio-sphere into different, related sections, which makes the relationships easier to understand. These sections are the niche, the habitat, and the ecosystem.

Many different kinds of scientists study the biosphere, using many kinds of tools.

Some scientists go into the field to study animals and plants in their native environments. Some scientists study cellular processes in the laboratory with sophisticated equipment. Some do experiments to see how changes in the environment result in changes in the organism.

NASA scientists use remote sensing to observe a section of the earth each orbit, and then combine the data from many orbits to recreate the whole earth at once. Sensors in space observe the earth in many different wavelengths of light. Combinations of these images can be used to determine what is growing in each patch of the earth, and even if it is healthy or not. As sensors get better and more sensitive, the size of the smallest patch that can be observed from space gets smaller and smaller – to within a few meters now. Remote sensing data can be used in estimating biomass, soil moisture, changes in elevation, or even animal population densities.

At a smaller scale, other scientists may investigate the processes involved in cycling water and the elements of life through the biosphere: carbon, nitrogen, sulfur, phosphorous, and other elements. These studies can also provide “ground-truth” – observations on the ground which are used to validate the remotely sensed data. As more and more observational and experimental data become available, other scientists construct models to help us understand the biosphere, how it evolved, and even provides tools that allow for predicting the future response of the biosphere to global change and human activities.

Picture Credit : Google

As far as we know, the Earth is the only planet in our Solar System capable of supporting life. It has all the things necessary to support life as we know it — water, carbon, oxygen, nitrogen and an abundant supply of food. Life on Earth is incredibly diverse, and the systems that support it are very complex.

Although the exact process by which life formed on Earth is not well understood, the origin of life requires the presence of carbon-based molecules, liquid water and an energy source. Because some Near-Earth Objects contain carbon-based molecules and water ice, collisions of these object with Earth have significant agents of biologic as well as geologic change.

For the first billion years of Earth’s existence, the formation of life was prevented by a fusillade of comet and asteroid impacts that rendered the Earth’s surface too hot to allow the existence of sufficient quantities of water and carbon-based molecules. Life on Earth began at the end of this period called the late heavy bombardment, some 3.8 billion years ago. The earliest known fossils on Earth date from 3.5 billion years ago and there is evidence that biological activity took place even earlier – just at the end of the period of late heavy bombardment. So the window when life began was very short. As soon as life could have formed on our planet, it did. But if life formed so quickly on Earth and there was little in the way of water and carbon-based molecules on the Earth’s surface, then how were these building blocks of life delivered to the Earth’s surface so quickly? The answer may involve the collision of comets and asteroids with the Earth, since these objects contain abundant supplies of both water and carbon-based molecules.

Once the early rain of comets and asteroids upon the Earth subsided somewhat, subsequent impacts may well have delivered the water and carbon-based molecules to the Earth’s surface – thus providing the building blocks of life itself. It seems possible that the origin of life on the Earth’s surface could have been first prevented by an enormous flux of impacting comets and asteroids, then a much less intense rain of comets may have deposited the very materials that allowed life to form some 3.5 – 3.8 billion years ago.

Comets have this peculiar duality whereby they first brought the building blocks of life to Earth some 3.8 billion years ago and subsequent commentary collisions may have wiped out many of the developing life forms, allowing only the most adaptable species to evolve further. It now seems likely that a comet or asteroid struck near the Yucatan peninsula in Mexico some 65 million years ago and caused a massive extinction of more than 75% of the Earth’s living organisms, including the dinosaurs. At the time, the mammals were small burrowing creatures that seemed to survive the catastrophic impact without too much difficulty. Because many of their larger competitors were destroyed, these mammals flourished. Since we humans evolved from these primitive mammals, we may owe our current preeminence atop Earth’s food chain to collisions of comets and asteroids with the Earth.

Picture Credit : Google

Some fish are bred in controlled conditions called fish farms. Fish farmers build special pens in lakes, ponds or estuaries. Here, they hatch fish from eggs and keep them until they are big enough to sell. Also known as “aquaculture”, fish-farming is becoming increasingly common. Freshwater fish farms breed salmon, carp and trout. Oysters and other shellfish are popular in coastal fish farms.

Fish farming is a form of aquaculture in which fish are raised in enclosures to be sold as food. It is the fastest growing area of animal food production. Today, about half the fish consumed globally are raised in these artificial environments. Commonly farmed species include salmon, tuna, cod, trout and halibut. These “aquafarms” can take the form of mesh cages submerged in natural bodies of water, or concrete enclosures on land.

According to the United Nations Food and Agriculture Organization, roughly 32% of world fish stocks are overexploited, depleted or recovering and need of being urgently rebuilt. Fish farming is hailed by some as a solution to the overfishing problem. However, these farms are far from benign and can severely damage ecosystems by introducing diseases, pollutants and invasive species. The damage caused by fish farms varies, depending on the type of fish, how it is raised and fed, the size of the production, and where the farm is located.

One significant issue is that—rather than easing the impact on wild populations—the farms often depend on wild fish species lower on the food chain, like anchovies, in order to feed the larger, carnivorous farmed species. It can take up to five pounds of smaller fish to produce one pound of a fish like salmon or sea bass. Overfishing of these smaller “forage” fish has repercussions throughout the ocean ecosystem.

As is the case with industrial animal farms on land, the fish are often housed in unnaturally crowded and cramped conditions with little room to move. Fish may suffer from lesions, fin damage and other debilitating injuries. The overcrowded and stressful conditions promote disease and parasite outbreaks—such as sea lice—that farmers treat with pesticides and antibiotics. The use of antibiotics can create drug-resistant strains of diseases that can harm wildlife populations and even humans that eat the farmed fish.

Escaped fish introduce yet another threat into the environment. Each year, hundreds of thousands of fish escape farms and threaten the genetic diversity and survival of native species. High stocking densities result in a significant amount of pollution from fish excrement and uneaten food, which in turn lead to poor water quality high in ammonia and low in oxygen. Outdoor fish farms can also attract predatory marine animals, such as sea birds and sea lions, who are sometimes poisoned or shot by aqua farmers for eating the fish.

Despite evidence to the contrary, it is still a common misconception that fish do not feel pain. Slaughter methods in the aquaculture industry are appalling. Little to no attention is given to the suffering of the animals and most are fully conscious during slaughter, which can take many minutes. Some species, such as salmon in the United States, are also starved for many days to empty the gut before they are sent to slaughter. Fish are most often not stunned and are killed by bleeding out, being hit on the head repeatedly, suffocating or freezing. In the US, as with many other countries, there are no regulations to ensure the humane treatment of fish.

Years of unregulated and underreported catches of Bluefin tuna in the Mediterranean Sea and Atlantic Ocean are threatening the existence of this severely overfished species. To meet the high and growing demand for sushi in Japan and elsewhere, ranching of Bluefin tuna is becoming a popular industry and is exacerbating the problem. Fisherman use longlines and purse seines to catch the tuna before they reach breeding age and have time to reproduce. They are then kept in sea farms for 3–6 months and fattened with thousands of pounds of smaller wild-caught fish before being killed and exported.

Picture Credit : Google

Shellfish such as crabs and lobsters are caught using baskets or netting pots. These baskets or pots sit on the seabed, with their position marked on the surface by a floating buoy. The opening of the basket or pot is designed so that the fish can get inside easily but cannot get out.

Pots and traps are generally rigid structures into which fish or shellfish are guided or enticed through funnels that make entry easy but from which escape is difficult.  There are many different styles and designs; each one has been designed to suit the behaviour of its target species. Many designs have evolved over many years to suit the coastline and seabed where it is used only changing to make use of modern materials.

In certain circumstances there may well be instances of Ghost fishing of lost pots and traps but this can be minimized by using appropriate gear and release devices.  One of the main causes of gear losses is the interaction of mobile gear with static gear. Nowadays the instances of this should be fewer due to the improvements in communication between different commercial fishing sectors and the ability to accurately monitor gear placement using GPS systems.

By-catch is minimal and usually confined to small animals of the target species. This can be minimized by the use of appropriate mesh sizes in the cover netting and the use of relevant escape gaps.  Any by-catch in the pots can be easily removed from the trap and released back into the sea immediately without harm.

Seabed impact with pots and traps is limited to light contact of the traps and minimal penetration of the seabed from the small anchors or weights that are used at the ends of the fleets of some gears. There may be some movement of the gear and the ropes on the seabed particularly in poor weather but this will not have much effect on the seabed.

Traps, in various forms of cages or baskets, have been used throughout the world for thousands of years to catch a wide variety of fish and shellfish. The basic design has not changed much over the years; the major changes have been in the materials that are used to make the gear. Early gear would have been made with wicker or willow, woven into a basket-form with a tapered entrance in the top, and stones inside to weight them down on the seabed. Nowadays, the pots and traps are made, along similar lines to the old wicker ones, but using modern materials such as wood, steel, plastic, etc. for the frame; this being covered with nylon and polyethylene netting.

Modern pots and traps tend to differ in shape, size and construction materials according to the behaviour of the target species, and local fishing practices. However, they will all be similar in that they will have at least one tapered entrance that makes it easy for the shellfish to enter, but very difficult for them to find their way out again. There is a big variation in the names of the different traps in different fisheries, with them being referred to most commonly as pots, creels, traps — but there will be numerous different local names for the different styles of pot. The pots are baited, usually with some type of fish. As with the pot construction, the choice of bait varies greatly with the locality and the target species, with some baits proving much more suitable for certain species than others. Despite this, it often comes down to what type of bait is readily available, and at a reasonable price.

Picture Credit : Google

The areas of seas and oceans where most fish are caught are called fishing grounds. Most of the world’s fishing grounds are found above the continental shelf — relatively shallow areas around the coastlines of the world. Fish are attracted to these areas because ocean currents create feeding grounds there.

If you’re anything like us here at Fusion, you can’t wait for the holidays to come so you can brush the dust off the boat and take her out for a fish.

Over the years, we’ve curated a list of what we think the best few fishing spots around the world are. Hopefully you get a chance to check one or two of them out next time you hit the water!

Cairns, Australia

Famous for its Great Barrier Reef, the coast off Eastern Australia is also the world’s best marlin fishing spot. These 750kg+ monsters inhabit the coastline between Cairns and Lizard Island, terrorizing anglers with their dashes of up to 130km/h. For those brave enough to take on the challenge, you’ll want to head there between early September and late December. The sun will be out, the water will be warm, and you’ll be among good company—more marlins are caught in this 250km stretch than anywhere else in the world combined!

Key West, Florida

If you’re looking for a great fishing spot, and a community absolutely obsessed with fishing, then look no further than Key West in Florida. Not only is this the gateway to the Dry Tortugas, renowned for their fishing, but the town has everything an angler could need. From seafood restaurants, through to great moorage and accommodation, you’ll be well catered for as you explore the sparkling blue waters and reefs amidst some of the world’s best fishing grounds. Thanks to the weather, any time of the year you’ll find good fishing at Key West, so head on out next time you get a few spare days.

Azores, Portugal

For those chasing fame and glory in their fishing exploits, you’re going to want to head over to the Azores archipelago off the coast of Portugal. No less than 22 world records are currently held for different species of catches made here—that’s right, the fish are big, and they bite! You’ll find all the classic game fish, as well as mako sharks and even the occasional whale sighting. If landing big catches in the shelter of stunning volcanic scenery sounds like your cup of tea, then Azores needs to be your next fishing destination.

Orkney Islands, Scotland

Europe’s playground. That’s what the Orkney Islands are known for, and with good reason: The absolute abundance of fish species makes fishing these waters an incredible time for anglers. What makes this Scottish spot unique is its intersection with nearby lochs and rivers, meaning you’re likely to catch all the usual salt water fish, alongside salmon, trout, bass and hake. Adding to that, the whole place has a surreal ancient vibe about it—mysterious stones and craggy cliffs give off a Viking feel, making the Orkneys an unmissable experience.

Prince Edward Island, Canada

Another spot known for its big game fishing and world records is Prince Edward Island, Nova Scotia in Canada. 40 years ago, the world’s largest bluefin tuna was landed in this spot, weighing in at a whopping 1,496 pounds. That’s literally like catching a horse! Besides ginormous fish, what makes Prince Edward Island great is the proximity of its fishing to shore. Usually you’ll find great spots less than a mile off the coast, which means half-day trips are much more sustainable. Get in some quality fishing, but also relax and enjoy your time in Canada—what more could a man want?

Coromandel Peninsula, New Zealand

If it’s beach, sun, relaxed-vibes and fishing that you’re after, then nothing beats the good old Coromandel in New Zealand. There’s a reason why Kiwis flock to this spot in the summer holidays—it’s white sandy beaches are great for the family to relax on, while Dad and his mates go out to fish around the mussel barges. You’ll find a real range of fishing options here too—from handlining for sprats off the rocks, to snapping up snapper a few hundred yards of the shore, through to big game fishing for kingfish and marlin further out. Take the boat out anywhere in the Coromandel, and you’re sure to come back relaxed, and full of fish.

Picture Credit : Google

Fishing is a very important global industry, but it can only exist as long as there are fish to catch. In some parts of the World, stocks of fish have decreased dramatically, due in part to modern fishing methods. As demand for fish has increased, so greater numbers of boats have fished the same areas. Technology has also made locating fish easier. Using nets too fine to allow small fish to escape has decreased the numbers of younger fish, which affects breeding and future stocks. While it is unlikely that stocks of fish will run out completely, many countries place strict controls on fishing, in an attempt to limit the damage.

It has been some time since most humans lived as hunter-gatherers – with one important exception. Fish are the last wild animal that we hunt in large numbers. And yet, we may be the last generation to do so.

Entire species of marine life will never be seen in the Anthropocene (the Age of Man), let alone tasted, if we do not curb our insatiable voracity for fish. Last year, global fish consumption hit a record high of 17 kg (37 pounds) per person per year, even though global fish stocks have continued to decline. On average, people eat four times as much fish now than they did in 1950.

Around 85% of global fish stocks are over-exploited, depleted, fully exploited or in recovery from exploitation. Only this week, a report suggested there may be fewer than 100 cod over the age of 13 years in the North Sea between the United Kingdom and Scandinavia. The figure is still under dispute, but it’s a worrying sign that we could be losing fish old enough to create offspring that replenish populations.

Large areas of seabed in the Mediterranean and North Sea now resemble a desert – the seas have been expunged of fish using increasingly efficient methods such as bottom trawling. And now, these heavily subsidised industrial fleets are cleaning up tropical oceans too. One-quarter of the EU catch is now made outside European waters, much of it in previously rich West African seas, where each trawler can scoop up hundreds of thousands of kilos of fish in a day. All West African fisheries are now over-exploited, coastal fisheries have declined 50% in the past 30 years, according to the UN Food and Agriculture Organisation.

Catches in the tropics are expected to decline a further 40% by 2050, and yet some 400 million people in Africa and Southeast Asia rely on fish caught (mainly through artisanal fishing) to provide their protein and minerals. With climate change expected to impact agricultural production, people are going to rely more than ever on fish for their nutritional needs.

The policy of subsidising vast fishing fleets to catch ever-diminishing stocks is unsustainable. In Spain, for example, one in three fish landed is paid for by subsidy. Governments, concerned with keeping jobs alive in the fishing industry in the short-term, are essentially paying people to extinguish their own long-term job prospects – not to mention the effect on the next generation of fishermen. Artisanal fishing catches half the world’s fish, yet it provides90% of the sector’s jobs.

Picture Credit : Google

The fishing industry uses several different methods to catch large numbers of fish. They mostly involve the use of nets. Trawling uses a cone-shaped net towed behind the fishing boat (known as a trawler). Purse-seining involves surrounding a school (group) of fish with a net and drawing the net lines together. Drift nets may be as long as 95km (60 miles). Left to drift in the water, they can catch many millions of fish at once.

Fishermen use a wide range of gear to land their catch. Every type has its own effects on the ocean. By selecting the right gear for the right job, the fishing industry can help minimize its impact on the environment.

Here are some methods and types of fishing, some more, some less popular:

Noodling is fishing with hands practiced in South of the United States. Fishermen catch catfish by sticking hand into a catfish whole where this fish lives.

Flounder tramping is a method of fishing practiced in Scottish village of Palnackie on every August. People compete in catching the flounder (which is a species of flatfish) by stamping on them.

Spearfishing is fishing with ordinary spears or with their variants like harpoons, tridents, arrows, Hawaiian slings, and superguns.

Netting is method of fishing which uses fishing nets. There are many types of nets for different uses and different fish. Cast net (or throw net) is a smaller round net with weights on it edges. Gillnet is placed in water vertically (using combination of weights and floats) and catches fish which try to pass through it. Trawl net is large, conical a dragged by ship.

Dredges

Dredges are metal-framed baskets that are dragged across the seafloor to collect clams, cockles, mussels, oysters, scallops and sea cucumbers. Towed dredges scrape or dig into the substrate with rakes or teeth to about a foot in depth. Mechanized dredges are used to dig and wash out mussels that have buried into the seabed. There are also hand-held dredges. This fishing method can have significant impacts on sensitive seafloor habitat and bottom-dwelling species. One way to limit these harmful effects is to limit the areas where dredging can occur.

Gillnets

Gillnets are walls of stationary or drifting netting that are almost invisible to fish, so species like cod, perch, salmon, sardines and trout swim right into them. Set, drift and trammel gillnet use different configurations of floats and weights to suspend the netting more or less vertically. Encircling gillnets are set in shallow waters, and noise or another means is used to entangle the fish in the netting. Fix gillnets are stretched between two or more stakes that are driven into the seabed in the intertidal zone. Gillnets can accidentally catch vulnerable ocean animals like sea turtles, marine mammals and sharks. These impacts can be reduced by setting the gillnets deeper in the water column to allow room for animals to swim over and adding gear like pingers, which warn passing marine mammals.

Pole-and-Lines

Pole-and-lines are poles with a single line, hook and bait that are used to catch a variety of fish ranging from open-ocean swimmers like tuna to bottom-dwellers like cod. They can be hand-operated or mechanized when operating in deep waters. Pole-and-line gears have very low catch of unwanted marine life because fishermen catch one fish at a time and they can release unwanted species.

Picture Credit : Google

A combine harvester is an important machine on a modern grain farm. It allows a very large amount of grain to be harvested very quickly. A combine harvester is so called because it does both of the processes involved in harvesting the grain — cutting the crop and separating the grain from the plant. Before the combine harvester, one or both of these jobs was done by hand or by two separate machines.

The crops we grow in our fields, such as wheat, barley, and rye, are only partly edible. We can use the seeds at the top of each plant (known as the grain) to make products like bread and cereal, but the rest of the plant (the chaff) is inedible and has to be discarded. Before modern-day machines were developed, agricultural workers had to harvest crops by carrying out a series of laborious operations one after another. First they had to cut down the plants with a long-handled cutting tool such as a scythe. Next, they had to separate the edible grain from the inedible chaff by beating the cut stalks—an operation known as threshing. Finally, they had to clean any remaining debris away from the seeds to make them suitable for use in a mill. All this took a lot of time and a lot of people. Thankfully, modern combine harvesters do the whole job automatically: you simply drive them through a field of growing crops and they cut, thresh, and clean the grains all by themselves using rotating blades, wheels, sieves, and elevators. The grain collects in a tank inside the combine harvester (which is periodically emptied into tractors that drive alongside), while the chaff spurts from a big exit pipe at the back and falls back down onto the field.

The Parts Explained:

Header: Cereal crops are gathered in by the header at the front, which has a pair of sharp pincers called crop dividers at either end. Generally speaking, the wider the header, the faster and more efficiently a harvester can cut a field. Different headers are used for cutting different crops; the header is often hydraulically powered and can be raised, lowered, and angled in different ways from the cab. The header can be removed and towed behind the harvester lengthwise so it can fit down narrow farm lanes.

Reel: A slowly rotating wheel called the reel (or pickup reel) pushes the crops down toward the cutter. The reel has horizontal bars called bats and vertical teeth or tines to grip the plant stalks.

Cutter Bar: The cutter bar runs the entire length of the header underneath the reel. Its teeth (sometimes called mowing fingers) open and close repeatedly to cut off the crops at their base, a bit like a giant electric hedge cutter sweeping along at ground level.

Conveyor: Behind the cutter bar, the cut crops are fed toward the centre by spinning augurs (screws) and travel up a conveyor to the processing mechanism inside the main part of the combine.

Threshing Drum: A threshing drum beats the cut crops to break and shake the grains away from their stalks.

Grain Sieve: The grains fall through sieves into a collecting tank below.

Straw Walkers: The chaff (unwanted material) passes along conveyors called straw walkers toward the back of the machine. More grain falls through into the tank.

Unloaded: When the grain tank is full, a tractor with a trailer on the back pulls alongside the combine. The grain is carried up from the tank by an elevator (a series of augers) and shoots out of a side pipe (sometimes called the unloader) into the trailer.

Straw & Chaff Removed: The unwanted straw and chaff tumbles from the back of the machine. Some combines have a rotating spreader mechanism that throws the straw over a wide area. Usually, the straw is baled up by a baling machine and used for animal bedding.

Picture Credit : Google

Grain in the form of wheat, corn (maize) or rice is the most important food crop in the world. As the basic ingredient of bread, wheat is grown throughout the world, often in very large quantities. Rice is grown in paddy fields throughout Asia, forming the basic foodstuff in that part of the world. Intensive farming methods mean that the amount of grain grown per hectare (the yield) in the USA is four times that produced from the same area in Africa.

Although there are thousands of edible plant species, only a relatively small number have been domesticated, i.e. converted to widespread usage by humans. Three crops—wheat, corn, and rice—provide nearly 60 percent of total plant calories that humans consume. Other major crops include potatoes, soybeans, cassava, sorghum, and legumes. The three top crops are grown worldwide, though certain regions are known for specific crops. For example, the United States supplies almost half of the world’s 800 million tons of corn annually, followed by China, Brazil, and Mexico. China, India, and the U.S. are the largest wheat producers, and almost 95 percent of all rice is grown in Asia. And, while 16 percent of total wheat production reaches the world’s markets, rice is primarily consumed where it is grown and only 5 percent makes it to the world market.

Wheat is one of the oldest cultivated crops, beginning around 10,000 years ago in the area known today as the “Fertile Crescent” between the Tigris and Euphrates rivers. Evidence suggests that wheat was used for making bread in Egypt by 5000 BC and its cultivation had spread to Europe by 4000 BC. Although the U.S. is the third largest wheat producer in the world, large-scale cultivation did not begin until the late 1800s when European settlement moved into the central plains. Today, approximately 700 million tons of wheat are grown annually around the world.

Corn (or maize) is thought to be a domesticated version of the wild cereal grass teosinte, and was likely cultivated between three and four thousand years ago in Mesoamerica. It is still one of the most common crops grown in the Americas. Only about one percent of the corn that is grown is eaten as whole or processed grain (sweet corn, corn chips, or tamales); more than 50 percent is used as animal feed—primarily for cattle, hogs, and chickens—and the remainder is consumed either as starch or in the form of corn sweeteners. More recently, an increasing amount of land area has been dedicated to growing corn due to the demand for ethanol, a corn-based fuel. In 2007, ethanol production became the second largest use of corn grown in the U.S. The sustainability of this use is controversial.

Rice continues to be a critical staple for nearly half of the world’s population, and for whom rice cultivation is the sole or primary source of food. Although rice is a good carbohydrate source, it does not provide adequate nutrition—an issue of increasing concern in the developing world where almost three billion people obtain most of their daily nutrients from rice. These populations can suffer from micronutrient deficiencies, most notably a lack of vitamin A.

Potatoes, cassava, beans, and other fruits and vegetables, however, provide humans with many essential nutrients. In the last two decades, the international trade in fruits and vegetables has become increasingly global and less tied to the seasons. The number of different types of fruits and vegetables on the world market has also expanded. As trade has grown, however, crops such as the banana, avocado, and cacao (for chocolate) are facing pressure from increasing worldwide demand, high disease rates, and land loss resulting from urbanization.

Picture Credit : Google

In many developing countries, subsistence farming is a common way of life. Farmers will normally grow just enough to food to feed themselves and their families, occasionally selling or trading surplus produce at local markets. They will keep small numbers of animals, sometimes for their meat, but more often to work the land.

Subsistence farming, or subsistence agriculture, is a mode of agriculture in which a plot of land produces only enough food to feed the family or small community working it. All produce grown is intended for consumption purposes as opposed to market sale or trade. Historically and currently a difficult way of life, subsistence farming is considered by many a backward lifestyle that should be transformed into industrialized communities and commercial farming throughout the world in order to overcome problems of poverty and famine. The numerous obstacles that have prevented this to date suggest that a complex array of factors, not only technological but also economic, political, educational, and social, are involved. An alternative perspective, primarily from the feminist voice, maintains that the subsistence lifestyle holds the key to sustainability as human relationships and harmony with the environment have priority over material measures of wealth. Although the poverty suffered by many of those who have never developed beyond subsistence levels of production in farming is something that needs to be overcome, it does appear that the ideas inherent in much of subsistence farming—cooperation, local, ecologically appropriate—are positive attributes that must be preserved in our efforts to improve the lives of all people throughout the world.

Subsistence farming is a mode of agriculture in which a plot of land produces only enough food to feed those who work it—little or nothing is produced for sale or trade. Depending on climate, soil conditions, agricultural practices and the crops grown, it generally requires between 1,000 and 40,000 square meters (0.25 to 10 acres) per person.

A recognizably harsh way of living, subsistence farmers can experience a rare surplus of produce goods under conditions of good weather which may allow farmers to sell or trade such goods at market. Because such surpluses are rare, subsistence farming does not allow for consistent economic growth and development, the accumulation of capital, or the specialization of labor. Diets of subsistence communities are confined to little else than what is produced by community farmers. Subsistence crops are usually organic due to a lack of finances to buy or trade for industrial inputs such as fertilizer, pesticides or genetically modified seeds.

Picture Credit : Google

The first farmers grew and cultivated crops in the Middle East around 12,000 years ago. Different varieties of wheat and barley were the main crops. They were grown, as they are today, to produce grain to make bread. Knowledge of farming spread from the region into Europe and Asia, while the native peoples of North and South America began farming around 7000BC.

“From what our current research reveals, the first indication for the earliest cultivation is 23,000 years ago on the shores of the Sea of Galilee in Israel,” Dr. Ehud Weiss, professor of palaeoethnobotany at Bar-Ilan University in Israel and the lead author of the study, told The Huffington Post in an email. “This is one of the most amazing finds a researcher can dream on. No one had previously imagined humans had started cultivating in such an early date.”

For the study, the researchers analyzed a 23,000-year-old hunter-gatherer campsite, which was discovered in 1989 at the archaeological site Ohalo II near the Sea of Galilee. They examined about 150,000 plant specimens at the site and noticed evidence not only of domestic-type wheat and barley, but also of weeds known to flourish in the fields of domesticated crops.

“The plant remains from the site were unusually well-preserved because of being charred and then covered by sediment and water which sealed them in low-oxygen conditions,” Weiss said in a written statement. “Due to this, it was possible to recover an extensive amount of information on the site and its inhabitants.”

The site also yielded flint tools that might have been used for harvesting cereal plants. Given the findings, the researchers concluded that the campsite is probably the earliest known example of small-scale farming. 

“While full-scale agriculture did not develop until much later, our study shows that trial cultivation began far earlier than previously believed, and gives us reason to rethink our ancestors’ capabilities,” Dr. Marcelo Sternberg, an ecologist at Tel Aviv University and a co-author of the study, said in a separate statement.  “Those early ancestors were cleverer and more skilled than we knew.”

Demand for food in the modern world means that the production of crops and livestock needs to be maximized. Many farms use a range of machinery and chemicals to practice what is known as intensive farming. Tractors plough fields and plant seed, while combine harvesters cut the crops at harvest time. Animal pests are controlled with pesticides, and weeds are destroyed with herbicides. Intensive farming methods often raise concerns about animal welfare, as livestock may be kept indoors in cramped conditions for long periods of time.

Intensive farming or intensive agriculture is a kind of agriculture where a lot of money and labour are used to increase the yield that can be obtained per area of land. The use of large amounts of pesticides for crops, and of medication for animal stocks is common. This is a contrast to traditional agriculture, which does not get as much output per area. When agriculture is intensified, this means that the amount of work needed goes up, until the worker is replaced by a machine. At that point, there will only need to be a few workers to operate the machines. Intensive farming has often been done as a response to rising population levels. It is criticised, because the standards of animal welfare are low. Intensive animal farming leads to increased pollution and to health issues.

Modern day forms of intensive crop based agriculture involve the use of mechanical ploughing, chemical fertilizer, plant growth regulators or pesticides. It is associated with the increasing use of agricultural mechanization, which have enabled a substantial increase in production, yet have also dramatically increased environmental pollution by increasing erosion and poisoning water with agricultural chemicals.

Picture Credit : Google

Deserts are hot, dry areas formed by the constant weathering and erosion of the land by fierce winds, extreme temperatures and occasional flows of water. They can contain barren mountain ranges, vast canyons cut into the Earth and huge plains covered with rocks or sand dunes. Many deserts have unusual rock formations, produced by certain kinds of erosion caused by wind and sand.

Sand covers only about 20 percent of the Earth’s deserts. Most of the sand is in sand sheets and sand seas–vast regions of undulating dunes resembling ocean waves “frozen” in an instant of time.

Nearly 50 percent of desert surfaces are plains where eolian deflation–removal of fine-grained material by the wind–has exposed loose gravels consisting predominantly of pebbles but with occasional cobbles.

The remaining surfaces of arid lands are composed of exposed bedrock outcrops, desert soils, and fluvial deposits including alluvial fans, playas, desert lakes, and oases. Bedrock outcrops commonly occur as small mountains surrounded by extensive erosional plains.

Oases are vegetated areas moistened by springs, wells, or by irrigation. Many are artificial. Oases are often the only places in deserts that support crops and permanent habitation.

Underground channels carry water from nearby mountains into the Turpan Depression of China. If the channels were not covered, the water would evaporate quickly when it reached the hot, dry desert land.

Soils that form in arid climates are predominantly mineral soils with low organic content. The repeated accumulation of water in some soils causes distinct salt layers to form. Calcium carbonate precipitated from solution may cement sand and gravel into hard layers called “calcrete” that form layers up to 50 meters thick.

Caliche is a reddish-brown to white layer found in many desert soils. Caliche commonly occurs as nodules or as coatings on mineral grains formed by the complicated interaction between water and carbon dioxide released by plant roots or by decaying organic material.

Most desert plants are drought- or salt-tolerant. Some store water in their leaves, roots, and stems. Other desert plants have long tap roots that penetrate the water table, anchor the soil, and control erosion. The stems and leaves of some plants lower the surface velocity of sand-carrying winds and protect the ground from erosion.

Deserts typically have a plant cover that is sparse but enormously diverse. The Sonoran Desert of the American Southwest has the most complex desert vegetation on Earth. The giant saguaro cacti provide nests for desert birds and serve as “trees” of the desert. Saguaro grow slowly but may live 200 years. When 9 years old, they are about 15 centimeters high. After about 75 years, the cacti are tall and develop their first branches. When fully grown, saguaro are 15 meters tall and weigh as much as 10 tons. They dot the Sonoran and reinforce the general impression of deserts as cacti-rich land.

Although cacti are often thought of as characteristic desert plants, other types of plants have adapted well to the arid environment. They include the pea family and sunflower family. Cold deserts have grasses and shrubs as dominant vegetation.

Picture Credit : Google

The floor of a forest is teeming with wildlife. Decaying vegetation provides food for insects and allows many kinds of fungi to grow. The warm, humid atmosphere of a tropical rainforest is the perfect environment for plants and mosses that thrive in shady areas. Palm trees will grow here amongst other young trees growing towards the forest canopy. Climbing plants such as liana twist and curl around the trunks of the trees.

The forest floor, also called detritus, duff and the O horizon, is one of the most distinctive features of a forest ecosystem. It mainly consists of shed vegetative parts, such as leaves, branches, bark, and stems, existing in various stages of decomposition above the soil surface. Although principally composed of non-living organic material, the forest floor also teems with a wide variety of fauna and flora. It is one of the richest components of the ecosystem from the standpoint of biodiversity because of the large number of decomposers and predators present, mostly belonging to invertebrates, fungi, algae, bacteria, and archaea. Certain (adapted) plants may be more apparent in tropical forests, where rates of metabolism and species diversity are much higher than in colder climates.

The major compartments for the storage of organic matter and nutrients within systems are the living vegetation, forest floor, and soil. The forest floor serves as a bridge between the above ground living vegetation and the soil, and it is a crucial component in nutrient transfer through the biogeochemical cycle. Much of the energy and carbon fixed by forests is periodically added to the forest floor through litterfall, and a substantial portion of the nutrient requirements of forest ecosystems is supplied by decomposition of organic matter in the forest floor and soil surface. The sustained productivity of forests is closely linked with the decomposition of shed plant parts, particularly the nutrient-rich foliage. The forest floor is also an important fuel source in forest fires.

The amount of material in the forest floor depends on the balance between inputs from litter production and outputs from decomposition, and amounts also reflect the site’s disturbance history. Both litter production and decomposition are functions of the site (e.g., wet versus dry; cold versus warm; nutrient rich versus nutrient poor) and the vegetation that occupies the site (e.g., conifer versus broadleaf). A site’s forest floor is determined by its areal weight, depth, and nutrient content. Typically, forest floors are heaviest and deepest in boreal forests and mountain forests where decomposition rates are slow. In contrast, the lightest and thinnest forest floors usually occur in tropical forests where decomposition rates are rapid, except on white sands where nutrients could not be supplied from mineral weathering.

Picture Credit : Google

The world’s forests provide many resources for human beings. Trees are cut down for timber, which is used for many different purposes, from building materials and fuel to making paper and chemicals. Forest areas are also cleared to create land for farming and other uses. There is a great deal of concern about the rate at which rainforests in particular are being destroyed. It is thought that an area of rainforest the size of a soccer pitch disappears every second. Such devastation has a dramatic effect on plant and animal species, as well as on the land itself.

As much as 80% of the world’s forests have been destroyed or irreparably degraded. Our ancient forests are looted every day to supply cheap timber and wood products to the world. The price for this destruction is escalating climate change, biodiversity loss and community displacement. And it’s happening in our region. Indonesia has lost 72% of its ancient forest, Papua New Guinea 60% and the Solomon Islands are predicted to lose all of them by 2014. Back in Australia, we are part of the problem.

The illegal and destructive logging operations are pushing species such as the orang-utan towards the brink of extinction and devastating local communities. What’s more, forest destruction accounts for around 20% of global carbon emissions. That’s more than the world’s entire transport sector.

Agri-business is responsible for massive rainforest destruction as forests are cleared or burned to make way for cattle ranches, palm oil or soya plantations. Irreplaceable rainforests are converted into products that are used to make toothpaste, chocolate and animal feed. Indonesia’s peatlands only cover 0.1% of the land on Earth, but thanks in part to the activities of the palm oil industry they contribute to 4% of global emissions. If expansion of the palm oil industry continues unabated, that figure can only rise.

Today, forests face another threat – climate change. When we destroy forests, we add to climate change because forests trap carbon and help stabilise the world’s climate. When forests are trashed, the carbon trapped in trees, their roots and the soil is released into the atmosphere. Deforestation accounts for up to 20% of all carbon emissions. This is why Indonesia is the world’s third largest greenhouse gas emitter after the US and China. At the same time, climate change itself threatens forests on a terrifying scale.

As their forest is cut down, millions of indigenous people suffer human rights abuse, and increased poverty and disease. Their food and medicine sources are destroyed. Their drinking water is polluted by soil erosion. With less than 5% of the logs’ value given back to the communities, the business of logging is moving landholders from subsistence affluence to a desperate type of poverty.

Some of the world’s most rare animals and plants call the last remaining rainforests in our region home. As their habitats are destroyed, many face extinction.

Picture Credit : Google

Forests can be classified according to a wide number of characteristics, with distinct forest type’s occurring within each broad category. However, by latitude, the three main types of forests are tropical, temperate, and boreal.

Tropical

Most tropical forests receive large amounts of rain annually (up to 100 inches), which is spread evenly throughout the year. However, there are some tropical forests that receive seasonal rainfall and experience both a wet and dry season. While tropical forests have many layers, most of the nutrients are held in the vegetation within the canopy; therefore, the soils are typically low in both mineral and nutrient content. Shallow roots allow for ‘catching’ any nutrients released by decaying leaves and ground litter.

Tropical forests are particularly important since they are unusually rich in bio­logical diversity, especially insects and flowering plants. This incredible amount of biodiversity—accounting for 50 to 80 percent of the world’s plant and animal species, with a potential for millions still undiscovered—is what defines these forests and makes them most unique. In just a few square kilometers, hundreds—even thousands—of tree and plant species can be found.

Deforestation is one of the greatest concerns in tropical areas, especially within rainforests which cover only a small area (approximately 7 percent) of the Earth’s surface. Aside from their vast biodiversity, tropical forests provide homes to a large number of indigenous people. And, in looking beyond the typical forest offerings, tropical forests supply both local and global markets with a variety of ingredients for medicines; nearly half of all medicines used today are linked to discoveries within these forests.

Temperate

Temperate forests—common throughout North America, Eurasia, and Japan—are primarily deciduous, characterized by tall, broad-leafed, hardwood trees that shed brilliantly colored leaves each fall. These forests experience varied temperatures and 4 seasons, with winter often bringing below freezing temperatures and summer bringing higher heat and humidity. Rainfall also varies, averaging 30 to 60 inches annually, allowing for soils that are well developed and rich in organic matter. They also provide habitat for a wide variety of smaller mammal species, including squirrels, raccoons, deer, coyotes and black bear and many bird species, including warblers, woodpeckers, owls, and hawks.

Temperate forests are often most affected by human activity since they are located in or near the most inhabitable areas. The land in these areas has long been used for agriculture and grazing, although great expanses of forest regeneration and small areas of pristine forest exist. The hardwoods are valuable for making furniture and other commodities, and many remaining forests have been modified to accommodate recreation and tourism.

Boreal

Boreal forests (also known as taiga) are located just south of the tundra and stretch across large areas of North America and Eurasia. They are one of the world’s largest biomes, encompassing about 11 percent of Earth’s land area, but have very short growing seasons with little precipitation and represent relatively few tree species. The forest is dominated by coniferous trees, which have needle-shaped leaves with minimal surface area to prevent excessive water loss. These forests provide habitat for a few large mammal species, such as moose, wolves, caribou, and bears, and numerous smaller species, including rodents, rabbits, lynx, and mink.

Despite the remote locations and often inhospitable environment, boreal forests have long been a source of valuable resources. Fur trading began in the 1600s and continued well into this century. Boreal forests are also rich in metal ores—including iron—and coal, oil, and natural gas. Most importantly, the forest serves as a major source of industrial wood and wood fiber, including softwood timber and pulpwood. However, the low productivity rate in these forests leads to a slow rate of forest regeneration.

Picture Credit : Google

Forest will grow in areas where the temperature rises above 10°C (50°F) in the summer and the annual rainfall is more than 200mm (8in). The type of forest depends upon the local climate, the soil and the altitude. Forests that grow in the extreme north of the Northern Hemisphere are called boreal forests; temperate forests grow in areas of moderate climate in both the Northern and Southern Hemispheres. Tropical regions are best known for their vast, dense areas of rainforest.

Tropical rain forests grow around the equator in South America, Africa, and Southeast Asia. They have the highest species diversity per area in the world, containing millions of different species. Even though they cover only a small part of the earth, they house at least one half of all species. The temperature is stable year-round, around 27°C (60° Fahrenheit). As you can tell from the name, it rains a lot in these forests. Most tropical forests receive at least 200 cm (80 inches) of rain in a year. Tropical forests generally have a rainy and dry season.

The high temperatures, abundant rainfall, together with twelve hours of light a day promotes the growth of many different plants. One square kilometer (0.6 miles) can have up to 100 different tree species. Broadleaf trees, mosses, ferns, palms, and orchids all thrive in rain forests. The trees grow very densely together and the branches and leaves block most of the light from penetrating to the understory. Many animals adapted to life in trees — such as monkeys, snakes, frogs, lizards, and small mammals — are found in these forests.

The soil can be several meters deep, but due to nutrient leaching, it lacks most of the essential nutrients for plant growth. The thin topsoil layer contains all the nutrients from decaying plants and animals, and this thin layer sustains the many plant species in the forest. One might think that the soil would be very rich because it supports so much life, but when tropical forests are clear-cut, the soil is useless for agriculture after only a few years — when the topsoil becomes depleted.

Temperate forests occur in the next latitude ring, in North America, northeastern Asia, and Europe. There are four well-defined seasons in this zone including winter. In general, the temperature ranges from -30 to 30°C (-22 to 86 F) and the forests receive 75-150 cm (30-60 in) of precipitation per year. Deciduous — or leaf-shedding — trees make up a large proportion of the tree composition in addition to some coniferous trees such as pines and firs. The decaying fallen leaves and moderate temperatures combine to create fertile soil. On average, there are 3-4 tree species per square km. Common tree species are oak, beech, maple, elm, birch, willow, and hickory trees. Common animals that live in the forest are squirrels, rabbits, birds, deer, wolves, foxes, and bears. They are adapted to both cold winters and warm summer weather.

Temperate evergreen coniferous forests are found in the northwestern Americas, South Japan, New Zealand, and Northwestern Europe. These forests are also called temperate rain forests because of the large amount of rainfall they see. The temperature stays pretty constant throughout the year, with a lot of precipitation, 130-500 cm (50-200 in). All this rain creates a moist climate and a long growing season, which results in very large trees. Evergreen conifers dominate these forests. Common species are cedar, cypress, pine, spruce, redwood, and fir. There are still some deciduous trees such as maples and many mosses and ferns — resulting in a Jurassic-looking forest. Common animals roaming the woods are deer, elk, bears, owls, and marmots.

Picture Credit : Google