Global Warming and the Effect on Plant Diversity

Depletion of tropical forests is becoming one of the many worldwide dilemmas facing our planet. The rapid rate of deforestation is reaching disastrous limits as the demands for resources far exceed supplies. Rainforests provide a home to many species of plants, both known and unknown. Our dependencies on tropical plants are vast ranging from the daily essentials of food and shelter, to cures for cancer and possibly AIDS. As destruction of the rainforest continues, the effects on plants are immense through the loss of genetic diversity and the disappearance of species. Plant species extinction is reaching critical levels. With this extinction comes a cascade of effects on the ecosystems in which plants play a vital role. New medicinal studies and development will be hindered as plant diversity diminishes. Loss of biological diversity means loss of future potential for humanity. Human activities, direct and indirect, are major causes of rainforest depletion. Destruction of rainforests must be ceased before global warming gets out of hand and plant biodiversity is lost cutting off a vital life line forever.

Global warming is commonly referred to as an increase in the temperature of the lowest layers of Earth's atmosphere. Global warming has occurred in the distant past as the result of natural influences, but the term is most often used to refer to the warming predicted to occur as a result of increased emissions of greenhouse gases. Primary greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Carbon dioxide, as well as other greenhouse gases, is a very important factor in the vital cycles which sustain life on this planet. Plants use carbon dioxide in photosynthesis and release the oxygen necessary to maintain the lives of animal species, who through exhaling return carbon dioxide in atmosphere, completing the cycle. This is known as the greenhouse effect which is a natural process that made life on Earth feasible. Our planet's surface temperature would have been 33 degrees Celsius cooler, -18 C instead of present 15 C, if not for naturally occurring greenhouse gases.

By the greenhouse effect, in the discussions of the global warming and other environmental problems, scientists describe it as the enhanced effect which is caused by the increase of greenhouse gases from human sources. Science brings different theories about the primary causes of the global warming of atmosphere. Eventually, the processes that happen in the environment are so complex, even on local scale, that analyzing causes and effects of global processes leads scientists to controversial conclusions. Most scientists agree on certain facts. The Intergovernmental Panel of Climate Change officially concluded in 1996 that it has increased by somewhere in between 0.5 to 1.1 degrees Fahrenheit since the last century. The sea level has risen four to ten inches during the same period of time. The main issues which arise are not only scientific, but also are political arguments which are the humans' contribution to the current warming of the atmosphere.

One theory states that the primary cause of the global increase of the temperature is the consequence of the sun activity. Sunspot cycles, which range between 9 to 13 years, are determining the amount of the sun radiation which is released in space and received by Earth in particular. A large group of scientists see the cause of the current temperature change due to human activities such as burning of fossil fuels in the course of the past two centuries since the beginning of the industrial revolution and active deforestation of the planet's surface. Oil, coal and natural gas are fossil fuels formed in Earth from the remains of plants and animals. They are rich in carbon and, when burned, produce carbon dioxide. Fossil fuels have been largely used by humanity since eighteenth century to produce heat. At present they are mostly used to produce electricity.

The human influence on the environment was not crucial when the population of the planet was much smaller. At the beginning of our era approximately 250 million people lived on Earth and by 1650 the population had grown only to 500 million. Yet, the rapid growth of population, starting in the nineteenth century, coincided with the development of the industry making the impact of the humanity on the environment, and in particular on the temperature change, considerable. In 1830 the planet population reached one billion, in 1930 it reached two billion, and four billion around 1975. In 1990 it was estimated 5.3 billion. It is clear that the growing population is consuming more resources, using more energy.

One of the most growing environmental concerns of our planet is the loss of tropical forests. Tropical forests are depleting at an alarming rate. A rate where demand far exceeds the supply. Of all the forest habitats, none seems to be more threatened than the tropical rainforests, as the world loses up to 20 million hectares of these forests annually, an 80 percent increase over previous estimates. In 1950, 30 percent of the world's surface was covered by rainforests. By 1975 this area had shrunk to 12 percent. Today, tropical forests account for about 8 percent of the planet's surface, an area roughly equal to that of the United States, constituting slightly less than half their prehistoric cover. Findings have shown that Africa has lost 60 percent of its original rainforests and Central America and Southeast Asia have lost nearly two thirds. During the 1980's, rates of clearance were approximately 1.8 percent annually, an area equal to the state of Florida. What is more tragic is similar rates of rainforest clearance are continuing and are on the rise.

Trees are not the only victims of rainforest depletion. Rainforests contain a vast array of biodiversity of plant and animal species required for maintenance of our biosphere. Because the rate of tropical forest loss is so rapid, and the concentration of the world's species in these ecosystems is so great, a significant proportion of all plants and animals are likely to become extinct in the next few decades, possibly by 25 to 30 percent. As humankind continues to abuse their environment this frontier will quickly become a glimmer in the past.. According to ecologists, destruction of rainforests is one of the great tragedies of our time resulting in the greatest single set back to life's abundance and diversity since the first flickering of life almost 4 billion years ago. Because we are able to see trees in the forest, the misled assumption of the abundance of such a resource exists.

If nothing is done about the reduction of the carbon dioxide in atmosphere, at least about the human contribution, our planet will change in many relations. At present rate of increase of greenhouse