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{{B}}Passage Three{{/B}}

In the world of climate change, it is in theEarth’sCold regions where trends can most easily be seen. The cryosphere, where water is found in solid form, is among the most sensitive regions to temperature change.
The sensitivity of ice and snow to temperature changes is an early indicator of even relatively small differences, says University ofColorado atBoulder senior researcher RichardArmstrong. He has found that today’s receding and thinning sea ice, mountain glacier mass losses, decreasing snow extent, melting permafrost (永久冻土), and rising sea level are all consistent with warming.
Global mean temperatures have risen one degree Fahrenheit over the past 100 years, with more than half of the increase occurring in the last 25 years, observesArmstrong who is affiliated with the National Snow and IceDataCenter headquartered atCU-Boulder.
"As slight as that may seem, it’s enough to make a difference," saidArmstrong. "Now, long-term monitoring of a series of cold region, or cryospheric, parameters (参数) shows that for several decades the amounts of snow and ice around the world have been decreasing. "
The extent ofArctic sea ice is shrinking by about 3 percent per decade, but the trends are not uniform. While recent studies have indicated that the ice thickness also had decreased over several decades, new information shows that the ice may have thinned rapidly,Armstrong saiD、Examination of springtime ice thickness in theArctic Ocean indicates that the mean ice thickness decreased 1.5 meters (4. 8 feet) between the mid-1980s and early 1990s.
To mark its 25^th anniversary, the National Snow and IceDataCenter has organized a special session at the 2001 Fall Meeting ofAmerican Geophysical Union, taking place this week in San Francisco, that illuminates overall changes in the cryosphere.
The session begins Tuesday and extends through Thursday afternoon, with 75 contributions from all areas of cryospheric study. Papers and posters include examinations of lake and river ice, glacier dynamics, and mass ice balance studies in polar and continental glaciers, regional and polar snow cover trends, and variations inCanadian ice cap elevations.

The signs of global warming include all of the followingEXCEPT ______ .A．thinning sea ice
B．decreasing snow extent
C．melting permafrost
D．falling sea level