Global Warming.

During the 1990s global warming became a major concern for scientists and the public. Many scientists warned that carbon dioxide and other gases from the burning of fossil fuels were collecting in the atmosphere and acting like the glass walls of a green-house, trapping heat on the surface of the Earth. They predicted that average temperatures could rise as much as 6.3 degrees F (3.5 degrees C) over the next century, threatening coastal areas with flooding as the polar ice caps melted and warmer sea waters expanded, and causing massive climate changes throughout the world. They cited evidence of heat waves, shrinking polar ice, and rising seas, all thought to be caused by global warming, and pointed to specific evidence that global warming was no longer a potential but a real threat to the environment. In Antarctica, Adelie penguin populations declined 33 per-cent in twenty-five...