the past several hundred years. The Upper Fremont Glacier and the Quelccaya Ice Cap in the Andes of South America both show nearly identical atmospheric records, which indicate a global linkage of atmospheric conditions over time. The small glaciers in the forest are less able to resist melting than the great ice sheets of Greenland and Antarctica. Once a glacier begins retreating, it may fall into disequilibrium and be unable to find mass balance (accumulation versus melting rate) at any size. Without a favorable climate change, it will continue to retreat until it disappears. Loss of glacial ice already reduces the summer glacial runoff that supplies water to streams and lakes and provides a cold-water source vital to certain fish and plant species. This, in turn, may have a significant impact on the forest ecosystem over time. Climate Wyoming is an arid state, averaging of precipitation annually. However, Shoshone National Forest is located in and near some of the largest mountain ranges in the state, and consequently receives anywhere between annually. Higher elevations in the forest not only get more precipitation than lower elevations, but also have lower overall temperatures, with summertime highs around and lows near while lower elevations may be or warmer on average. Humidity levels throughout the forest are low, especially at higher altitudes. In the middle of the forest at the Wapiti Ranger Station, which is west of the forest headquarters in Cody, Wyoming, January high and low temperatures are , while the July highs and lows are . The annual precipitation at Wapiti is . Most of the precipitation falls in the winter and early spring, while summer is punctuated with widely scattered thunderstorms. The autumn is usually cool and dry. Due to the altitude and dryness of the atmosphere, vigorous radiative cooling occurs throughout the year, and exceptional daily temperature variances are not uncommon. Consequently, the nights range from very cool in the summer to extremely cold in the winter; therefore, visitors should always remember to bring along at least a jacket, even during the summer. Records indicate that the highest temperature ever recorded in the forest was in 1978, while the coldest was in 1972. Recreation Shoshone National Forest receives an average of over half a million visitors a year. Two visitor centers provide orientation, books, maps, and interpretive displays. One visitor center is at the Wapiti Wayside on the Buffalo Bill Cody