Query: Beginning in 2005, however, polar ice modestly receded for several years.

Relevant passages:
Arctic Ocean <=SEP=> The Arctic Ocean is the smallest and shallowest of the world 's five major oceans . The International Hydrographic Organization ( IHO ) recognizes it as an ocean , although some oceanographers call it the Arctic Mediterranean Sea or simply the Arctic Sea , classifying it a mediterranean sea or an estuary of the Atlantic Ocean . Alternatively , the Arctic Ocean can be seen as the northernmost part of the all-encompassing World Ocean .   Located mostly in the Arctic north polar region in the middle of the Northern Hemisphere , the Arctic Ocean is almost completely surrounded by Eurasia and North America . It is partly covered by sea ice throughout the year and almost completely in winter . The Arctic Ocean 's surface temperature and salinity vary seasonally as the ice cover melts and freezes ; its salinity is the lowest on average of the five major oceans , due to low evaporation , heavy fresh water inflow from rivers and streams , and limited connection and outflow to surrounding oceanic waters with higher salinities . The summer shrinking of the ice has been quoted at 50 % . The US National Snow and Ice Data Center ( NSIDC ) uses satellite data to provide a daily record of Arctic sea ice cover and the rate of melting compared to an average period and specific past years .

Retreat of glaciers since 1850 <=SEP=> 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 . Studied by glaciologists , the temporal coincidence of glacier retreat with the measured increase of atmospheric greenhouse gases is often cited as an evidentiary underpinning of global warming . Mid-latitude mountain ranges such as the Himalayas , Alps , Rocky Mountains , Cascade Range , 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 .   Glacier mass balance is the key determinant of the health of a glacier . 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 . Glaciers in retreat will have negative mass balances , and if they do not find an equilibrium between accumulation and ablation , will eventually disappear .   The Little Ice Age was a period from about 1550 to 1850 when the world experienced relatively cooler temperatures compared to the present . Subsequently , until about 1940 , glaciers around the world retreated as the climate warmed substantially . Glacial retreat slowed and even reversed temporarily , in many cases , between 1950 and 1980 as global temperatures cooled slightly . Since 1980 , a significant global warming has led to glacier retreat becoming increasingly rapid and ubiquitous , so much so that some glaciers have disappeared altogether , and the existences of many of the remaining glaciers are threatened . In locations such as the Andes of South America and Himalayas in Asia , the demise of glaciers in these regions has the potential to affect water supplies in those areas .   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 . 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 .