COLD, HARD FACTS ABOUT GLOBAL WARMING
September 30, 2004
Are glaciers, ice caps and sea ice melting worldwide because human industrial activity is causing global warming? Geologic history says otherwise.
Researchers from Montana State University found the fluctuation of glaciers at the Glacial National Park in Montana is the result of unique interactions between summer draught and winter snow concentrations rather than rising CO2 concentrations.
Using tree-rings and National Park Service observations, the researchers found numerous links between the variability of drought (also reconstructed through tree-rings) to glacier positions. Furthermore:
- During the late 19th century, a shift from cool and rainy conditions to drought coincides with the onset of glacial retreat from the previous ice age.
- Similarly, extreme drought between 1917 and 1941 coincided with rapid glacial recession in the park.
- Montana's glaciers began to retreat long before the atmospheric concentration of greenhouse gases began to change significantly.
Combining data on drought variability and winter snow-pack accumulation, the researchers were able to derive a 300-year index that provides a precise history of glacial dynamics. In other words, these two natural quantities account for the observed glacial variability over the last three centuries.
Though it is yet to be determined what potential effect CO2 concentrations may have on these drought and snow interactions, these findings show how natural phenomena can result in glacial retreat and advance for hundreds of years in the absence of greenhouse gases.
Source: "Cold, Hard Facts," Greening Earth Society, July 29, 2004.
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