In the past, scientists often referred to tropical rainforests as the "lungs of the world" because of the large amount of oxygen they produce. More recent evidence shows that rainforests don't have much of an effect on the world's oxygen supply. The decomposition of dead plant matter consumes roughly the same amount of oxygen that the living plants produce.
But rainforests do play a key role in the global ecosystem. Some experts are now calling them the "air conditioners to the world," because their dark depths absorb heat from the sun. Without the forest cover, these regions would reflect more heat into the atmosphere, warming the rest of the world. Losing the rainforests may also have a profound effect on global wind and rainfall patterns, potentially causing droughts throughout the United States and other areas.
The act of deforestation itself affects the environment as a whole. Roughly 30 percent of the carbon dioxide released in the air (a leading cause of global warming) comes from burning the rainforests.
In the past hundred years, humans have begun destroying rainforests at an alarming rate. Today, roughly 1.5 acres of rainforest are destroyed every second. People are cutting down the rainforests in pursuit of three major resources:
- Land for crops
- Lumber for paper and other wood products
- Land for livestock pastures
In the current economy, people obviously have a need for all of these resources. But almost all experts agree that, over time, we will suffer much more from the destruction of the rainforests than we will benefit. There are several factors involved in this scientific assessment:
- To begin with, the land in rainforest regions is not particularly suited for crops and livestock. Once the forest is cleared, it is even less so -- without any decomposing plant life, the soil is so infertile that it is nearly useless for growing anything. Generally, when people clear-cut a forest, they can only use the land for a year or two before the nutrients from the original plants are depleted, leaving a huge, barren tract of land.
- Cutting large sections of rainforest may be a good source of lumber right now, but in the long run it actually diminishes the world's lumber supply. Experts say that we should preserve most of the rainforests and harvest them only on a small scale. This way, we maintain a self-replenishing supply of lumber for the future.
- Rainforests are often called the world's pharmacy, because their diverse plant and animal populations make up a vast collection of potential medicines (not to mention food sources). More than 25 percent of the medicines we use today come from plants originating in rainforests, and these plants make up only a tiny fraction of the total collection of rainforest species. Fewer than 1 percent of rainforest plants have been examined for their medicinal properties. It is extremely likely that our best shot at curing cancer, AIDS and many other debilitating diseases lies somewhere in the world's diminishing rainforests. With some 137 rainforest species disappearing every day (the most rapid extinction rate in the history of the world), there's a good chance that we're losing valuable medicines by the minute.
The world's rainforest are an extremely valuable natural resource, to be sure, but not for their lumber or their land. They are the main cradle of life on Earth, and they hold millions of unique life forms that we have yet to discover. Destroying the rainforests is comparable to destroying an unknown planet -- we have no idea what we're losing. If deforestation continues at its current rate, the world's tropical rainforests will be wiped out within 40 years.
To learn more about rainforests and to find out what you can do to help with their preservation, check out the links on the next page.