Earth's surface has undergone unprecedented warming over the last century, particularly over the last two decades. To answer this question, patterns observed by meteorologists and oceanographers are compared with patterns developed using sophisticated models of Earth's atmosphere, oceans and on its land surfaces. Mathematical models allow scientists to simulate the behavior of complex systems such as climate and explore how these systems respond to natural and human factors.
As a result of an enormous scientific effort over the years to better understand the climate system and its relationship to human activities, there now is a growing consensus among mainstream scientists about the reality of global warming. The current levels of carbon dioxide (CO2) in the atmosphere are higher than at any time during the last 650,000 years. Science tells us with increasing certainty that we are in for a serious long-term problem that will affect all of us. Related links at: Earth Science»