Contact: Barbara McGehan IMMEDIATE RELEASE
Henry Diaz 9/11/96
Nicholas Graham
Warming of tropical sea surface temperatures may be contributing to the melting of high altitude tropical glaciers, according to researchers at the National Oceanic and Atmospheric Administration's Climate Diagnostics Center and Scripps Institution of Oceanography.
In the Sept. 12 issue of Nature, Henry F. Diaz of NOAA's Climate Diagnostics Center (CDC) and Nicholas Graham of Scripps say that a general warming of the climate system in recent decades is related to a long-term increase of sea surface temperatures in the tropics and the resulting enhancement of the tropical hydrologic cycle. According to the researchers, higher sea surface temperatures and atmospheric humidity in recent decades are consistent with glacial records which indicate that temperatures in the tropics are warmer than at any time in the past 2000-3000 years.
"Although changes in temperature are likely the dominant mechanism producing this melting, there is also evidence from both observations and models that the changes in temperature have been accompanied by widespread increases in the moisture content in the lower atmosphere due to the higher sea surface temperature," says Diaz. These increases in atmospheric humidity would also contribute to accelerated melting rates.
The study compared temperature changes in the tropics, based on instrument records for the past three to four decades, to the results of a general circulation model. "These observations underscore the unusual nature of the general warming of the climate system that has been recorded in recent years, especially the melting of tropical ice cap margins," reported Diaz.
Whether this recent increase is natural or caused by human activity remains to be seen. "Regardless of the cause, physical evidence suggests that high-elevation environments may be particularly sensitive to long-term changes in tropical sea surface temperature and atmospheric humidity. These factors are likely to impact the hydrologic and ecological balances of high-altitude zones throughout the globe, but especially in the tropics," says Diaz.
###Note: For more information on the Climate Diagnostics Center, consult the CDC home page at http://www.cdc.noaa.gov