Global Warming-a global catastrophe?

A Global Catastrophe?
Imagine being responsible for something like this. A giant asteroid hit the earth about 65 million years ago. The scientist speculated that the collision threw so much dust in to atmosphere that the world was dark for three years. As a result, sunlight was greatly reduced, plants could not grow, temperatures fell, the food chain collapsed, and many species, including the dinosaurs became extinct. We, as human beings, are causing something just as profound, but in a subtle manner, as the asteroid that felled the dinosaurs. According to the National Academy of Sciences, the Earth's temperature has risen about 1 degree Fahrenheit in the past century and global warming has accelerated dramatically during the past two decades. We have changed and continue to change the balance of gases that form the atmosphere, which leads to these climate change and global warming.
Most of the warming over the last 50 years is attributed to human activities. Human activities ...