Another government source said the United States intends to participate in the next round of U.N. talks, set for Bonn, Germany, in July. But the source added the administration is still weighing what it would bring to the table. A panel of the National Academy of Sciences reviewed the current body of knowledge about global warming at the request of the White House. Click above for highlights of the report. Greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise.
Temperatures are, in fact, rising.
The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes are also a reflection of natural variability. In the near term, agriculture and forestry are likely to benefit from carbon dioxide fertilization and an increased water efficiency of some plants. Some models project an increased tendency toward drought over semi-arid regions, such as the U.S. Great Plains. With higher sea level, coastal regions could be subject to increased wind and flood damage even if tropical storms do not change in intensity. The costs and risks involved are difficult to quantify at this point.