While others retreat, Mt. Shasta glaciers continue growing

05 December 2007 | 04:45 Code : 16142 Geoscience events
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Global warming conditions are causing glaciers around the world to retreat....

  Global warming conditions are causing glaciers around the world to retreat and disappear, but according to a 2006 report by Ian Howat and Slawek Tulaczyk of the Department of Earth Science, UC Santa Cruz, the glaciers of 14,162 foot Mt. Shasta are growing.A recent study, cited in National Geographic News, using satellites from the National Aeronautics and Space Administration and the Defense Department, concluded that “Mountain glaciers are melting faster than ever, and effects of the thaw are being seen from the summits of South America to the highest peak in Africa.”Howat spent considerable time on the mountain measuring snow and ice levels and recording scientific data. Among the methodologies used in the study were comparisons of aerial photographs going back to 1925, ice cores and comparison of snow fall measurements. Field data collection included the use high-precision Global Positioning System, ground penetrating radar and sonic distance metering.“Of particular interest is that unlike glaciers in the Cascades to the north and Rocky Mountains to the east, the glaciers of Mount Shasta have not appreciably retreated despite a sustained regional warming trend of several degree Celsius over the past 50 years,” the report states.“In fact,” the report continues, Whitney and Hotlum Glaciers have continued to expand from the mid-twentieth century through at least 2003 bucking the predominant global recessional trend.”US Forest Service climbing ranger Eric White says the mountain is in a unique climate range that accounts, in part, for the unusual glacier growth.“We're at the northern end of El Nino, that brings wetter tropical weather, and at the southern portion of La Nina, that brings cool and wet weather,” White said. “We see the benefit of both of these with increased precipitation and more snow at higher levels. Glaciers are rapidly retreating in the Sierra Nevada that is getting not as much precipitation and warmer temperatures.”“Despite a regional warming trend over the past few decades, Mount Shasta's ice volume has remained relatively stable due to a large increase in winter snow accumulation and strengthening correlation with positive El Nino phases,” the report says.Howat says an additional factor in the glacier growth is that Mount Shasta is “the only mountain in California whose summit is above the annual snow line on all sides.” That causes an “increase in spring snow accumulation at high elevations and, consequently, fosters glacier growth.”Howat warns, however, that as temperatures increase and the climate experiences further destabilization, the glaciers could recede and disappear.“The RegCM2.5 regional climate model estimates a large increase in summer temperatures relative to winter precipitation under greenhouse-driven warming that would result in the loss of most of Mount Shasta's glacier volume over the next 50 years, with near total loss by the end of the century,” the report says.US Forest Service hydrologist Steve Bachman says even if the glaciers disappear, the area's water sources will not be affected. Bachman said the water will simply be stored in a different medium.“The ground in our area has high permeability. Precipitation will increase and be stored in aquifers,” Bachman said. “It's just a different kind of storage.”White says glaciers are the “canary in the coal mine,” referring to the old tradition of using canaries as a warning of lack of oxygen by sending them into a mine before the miners.“Glaciers are a history of climate change you can see through ice cores,” White said. “Glaciers are very sensitive to climate change.”The study concludes that it is the increase in temperature that has caused the glaciers to not only remain stable, but grow.“The overall winter temperature increase of 1 degree centigrade over the past 110 years has been accompanied by an increase in winter precipitation of 17 percent, which is near the ratio required for stable volume predicted by the glacier models,” the study states.

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