Rainforests are one of the most complicated environments on Earth. They are recognized worldwide as containing the richest source of plants and animals and are believed to contain nearly three-quarters of all the varieties of life on Earth. This is remarkable because rainforests cover only about six percent of the Earth's land surface.
Rainforest are the oldest major ecosystem, having survived climate changes for more than one million years. They provide habitats for more species of plants, animals, insects and birds than any other environment found on our planet. Scientists estimate that between 60 and 90 percent of all species of life are to be found in rain forests. Unfortunately, the widespread destruction of many of the world's rainforests has caused a significant decline in the number of plant and animal species on Earth.
Rainforests influence both our local and global climates. For example, between 50 and 80 percent of the moisture in the air above rainforests comes from the rainforest's trees. If large areas of these lush rainforests are cleared, the average rainfall in the area will drop. Eventually, the area's climate will get hotter and drier. This process could convert rainforests into a sparse grassland or desert.
Rainforests are also able to absorb over 90 percent of the rainfall in their leaves and mosses. By doing this, they are able to slow down water run-off by gradually releasing the water over time into streams and rivers. This helps to control soil erosion and flooding.
Rainforests are vital to the Earth in helping to recycle carbon and oxygen. Carbon dioxide (CO2) is the gas put into the air globally by humans, mainly by the burning of fossil fuels (for example in cars and factories). Rainforests are able to remove carbon dioxide from the air and return oxygen in its place. This is why our global rainforests are often called the Earth's ‘lungs'.
Rainforests are major producers of the Earth's oxygen. In fact, scientists believe that nearly 50 percent of the Earth's oxygen is produced by rainforest in the Amazon region alone.
Nearly 40 percent of the world's carbon is contained in the trees of the rainforests. As rainforests are cut down and burned, carbon dioxide is released into the Earth's atmosphere. Eventually, as this gas builds up the atmosphere, leading to what scientists call the enhanced greenhouse effect.
To sum up, the role of the rainforest is essential for human life. It creates equilibrium in our environment and its resources are significant for human beings survival.
Taken from SOSE: Studies of Society and Environment, 2000