Abstract
In summary, the atmospheric concentrations of the principal anthropogenic greenhouse gases (CO2, CH4, N2O, CFC-11, and CFC-12) have increased significantly during the industrial period. Elevated concentrations are predicted to persist in the atmosphere for times ranging to thousands of years. The increased atmospheric levels of these gases, especially CO2, increase the IR energy absorbed by the atmosphere, thereby producing a warming influence at the Earth's surface. Global mean temperatures have increased between 0.3 and 0.6°C during the last 150 years.This change has not been monotonic, but it is unusual in the context of the last few centuries. On the timescale of the last few thousand years there have been larger climatic variation during times when variations in CO2 have been relatively low. It is clear that atmospheric CO2 is not the only influence on global climate. However, there have been large natural variations of CO2 in the geologic past, and these changes are correlated with general features of climate change.There is no known geologic precedent for large increases of atmospheric CO2 without simultaneous changes in other components of the carbon cycle and climate system. Changes in the climate system that are confidently predicted in response to increases in greenhouse gases include increases in mean surface air temperature, increases in global mean rates of precipitation and evaporation, rising sea level, and changes in the biosphere. Substantial uncertainties remain in the magnitudes and geographical distribution of these changes and in the rates at which they may be expected to occur.The significant recent progress in the scientific understanding of climate change and the uncertainties in predictions of climate change are documented in the peer-reviewed literature. Peer-reviewed scientific research provides the scientific basis for the AGU position statement on Climate Change and Greenhouse Gases and must continue to be utilized in informed decision making on this issue.
Original language | English (US) |
---|---|
Pages (from-to) | 453-454+457-458 |
Journal | Eos |
Volume | 80 |
Issue number | 39 |
DOIs | |
State | Published - 1999 |
Externally published | Yes |
ASJC Scopus subject areas
- General Earth and Planetary Sciences