Beginning of Essay
I have chosen to speak about Global warming because it is a major scientific issue in the media. Problems facing the environment today are vast and diverse. Destruction of the world's rain forests, the depletion of the ozone layer, air pollution, water pollution, ....

Middle of Essay
.... to alter the composition of the atmosphere. Vast supplies of charcoal, and later coal and oil, fed the growing fires of the Industrial Revolution. The carbon stored in these fuels was released to the air as carbon dioxide - a gas that traps heat in the atmosphere. Today, for every one of the more than 5.8 billion people on Earth, nearly six tons of carbon dioxide is spewed into the air every year. As a result of our activities, the gas trapped inside the atmosphere has risen by more than 30 percent in the last 250 years. These greenhouse gases which prevent infrared radiation from escaping into space, keep the earth's temperature warm. According ....