[T]he scientific case for human-caused climate change is clear. The evidence includes independent assessments of thermometer records documenting the degree and extent of modern warming. It includes the unprecedented melting of glaciers and, as documented in more recent years, the diminution of the Greenland and Antarctic ice sheet. As a consequence of melting ice and warming oceans, the global sea level is rising and at an accelerating rate. Continental drought is becoming more pronounced in many extratropical regions, such as the deserts of the U.S. Southwest, and there is an increase in the destructive potential of Atlantic hurricanes that influence the east and Gulf coasts. Theoretical climate models predict these things to happen, but only when human influences - in particular, increasing greenhouse gas concentrations due to fossil fuel burning—are included.
Those same models project far more profound and potentially damaging impacts of climate change if action is not taken to stabilize greenhouse gas levels this next decade...
Sadly, some who are opposed to taking action to combat the potential threat have engaged in a smear campaign that appears intended to distract the public and policymakers from the reality of the threat as policymakers begin to consider taking more serious action to reduce greenhouse gas emissions.