![]() ![]() The Little Ice Age was a period from about 1550 to 1850 when certain regions experienced relatively cooler temperatures compared to the time before and after. Glaciers in retreat will have negative mass balances, and if they do not find an equilibrium between accumulation and ablation, will eventually disappear. If the amount of frozen precipitation in the accumulation zone exceeds the quantity of glacial ice lost due to melting or in the ablation zone a glacier will advance if the accumulation is less than the ablation, the glacier will retreat. Glacier mass balance is the key determinant of the health of a glacier. The acceleration of the rate of retreat since 1995 of key outlet glaciers of the Greenland and West Antarctic ice sheets may foreshadow a rise in sea level, which would affect coastal regions. The retreat of mountain glaciers, notably in western North America, Asia, the Alps and tropical and subtropical regions of South America, Africa and Indonesia, provide evidence for the rise in global temperatures since the late 19th century. Excluding peripheral glaciers of ice sheets, total global glacial losses were likely 5500 gigatons over 1993–2018. Mid-latitude mountain ranges such as the Himalayas, Rockies, Alps, Cascades, Southern Alps, and the southern Andes, as well as isolated tropical summits such as Mount Kilimanjaro in Africa, are showing some of the largest proportionate glacial losses. Deglaciation occurs naturally at the end of ice ages, but glaciologists find the current glacier retreat is accelerated by the measured increase of atmospheric greenhouse gases-an effect of climate change. The retreat of glaciers since 1850 affects the availability of fresh water for irrigation and domestic use, mountain recreation, animals and plants that depend on glacier-melt, and, in the longer term, the level of the oceans. In all, about 25 percent of the ice that melted between 20 occurred in the Americas (excluding Greenland). ![]()
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