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Collectively forming the largest area of glacial cover outside of Alaska and the Arctic and referred to as Earth’s “third pole,” the Himalayan glaciers are important sources of water for the Indus, Ganges and Bhramaputra river basins, where 800 million people live. Best estimates suggest that the glaciers of the greater Himalaya cover about 15,800 [...]

Albedo describes how much of the Sun’s radiation an object reflects. New snow is very reflective, with an albedo as high as 0.9, meaning that 90 percent of the sunlight that hits it is reflected. Dark asphalt, on the other hand, has an albedo as low as 0.04, meaning it absorbs 96 percent of the [...]

In Brief: A warmer Arctic means slower-moving storm systems across the mid-latitudes. Spring is the time of year when the Arctic comes out of its long, dark winter and the sea ice that covers most of the Arctic Ocean in winter begins its annual melt. This melting continues through the warm summer months until the [...]

The last two million years of Earth’s history are characterized by swings from cold, glacial periods to warmer, interglacial periods. These swings are part of a cycle lasting about 100,000 years, controlled by gradual changes in Earth’s orbit and the amount of the sun’s energy received by the Earth. As the last warm interglacial ended [...]

Ice cover on the Great Lakes peaks in February or early March before beginning its gradual melt, which is generally completed by May or June. Deepwater lakes like Superior take longer to reach peak ice cover than shallow water lakes like Erie, and also take longer to thaw. This means that shallow water lakes are [...]

The extent of the Arctic sea ice, which is usually gauged by its annual minimum extent in September, has been declining by 11.2 percent per decade since 1979. Large-scale effects of this decline impact Earth’s climate, primarily through increased absorption of sunlight by the open oceans. Local effects have also been documented. As ice has [...]

In Brief: Variations in Earth’s orbit, combined with other processes such as vegetation shifts, control glacial/interglacial cycles. For at least the past two million years, Earth has moved between interglacial phases, like the past 10,000 years when ice cover was confined to the polar regions, and glacial phases, when large ice sheets extend into the [...]

The September/October Arctic sea ice annual minimum this year was the second lowest minimum on record for the 33 year period of satellite observations. The lowest minimum was recorded in 2007. But how do these ice extents relate to what the sea ice has done over the past several hundred or thousand years? Known relationships [...]

Paleoclimatology, the study of past climates and past climate changes, provides ample evidence that climate change can happen suddenly. Around 18,700 years ago, a section of the slowly melting Laurentide (North American) Ice Sheet, which at one point extended all the way from the Arctic to the Ohio River, disintegrated around present day Wisconsin. This [...]

In Brief: The silt cliffs on the Beaufort and Chuckchi Seas around Alaska are crumbling as water temperatures have warmed and the annual duration of the Arctic Sea Ice has declined. The Arctic, where the temperature rise has been twice the global average, has born some of the most visible impacts of the last 40 [...]

In Brief: Glaciers, a key source of water in the West, are melting more in the summer than they are growing during the winter. The glaciers that make the peaks of the Western United States white year round are located almost exclusively within National Forests and National Parks. In addition to providing scenery and tourist [...]

Average global sea level is rising by about three millimeters per year. There are three main contributors to this rise, each of which separately account for about one millimeter each: the thermal expansion of water, or the fact that warmer waters occupies more space than cooler water; the melting of mountain glaciers and ice caps; [...]

In Brief: Analysis of paleoclimatic data from the last interglacial period (130,000 to 120,000 years ago) suggests that most of the sea level rise came from the Antarctic Ice Sheet. The last interglacial period (LIG), which ran from about 130,000 to 120,000 years ago, was a particularly warm interglacial period with global temperatures about 3.6 [...]

In Brief: The extent of older Arctic sea ice, or ice that has survived at least one melt season, has been declining since 1980 with a melt rate acceleration beginning around 2002. The 2007 September Arctic sea ice minimum extent was the smallest on record. This ice has been in a declining trend since 2002, [...]

The Canadian Arctic Archipelago (CAA), which lies across Baffin Bay from the northwest coast of Greenland, holds about one third of Earth’s ice mass, excluding the giant Greenland and Antarctic Ice sheets. The Archipelago’s 36,500 islands cover 540,000 square miles including Baffin Island, the world’s fifth largest island covering close to 200,000 square miles. The [...]

How do sea levels vary as the world warms or cools? A warmer planet means more heat is stored in the oceans. More heat causes thermal expansion that pushes ocean waters onto the land. A warmer Earth also means more melting of the ice sheets and alpine glaciers that sit on the land surface, putting [...]

The northern circumpolar permafrost region –  located mostly above 60 degrees North or the southern tip of Scandinavia – is an area where temperatures are so cold that the soil remains permanently frozen, except for an active surface layer that is as shallow as a few inches deep. Beneath this active layer lie ancient carbon [...]

In Brief: The 1783-84 eruption of Iceland’s Laki volcano caused crop failures and a cold summer in North America, while the following winter’s record cold has been linked to El Niño conditions in the tropical Pacific and a strongly negative North Atlantic Oscillation. The eruption of Iceland’s Laki volcano from June 8, 1783 to February [...]

In Brief: Sunlight reflecting off snow covered forest floors gives extra energy to boreal forest trees as they come out of their winter dormancy. Boreal (Northern Hemisphere) spring is here. Even in the high northern latitudes, temperatures are beginning to warm and plants are beginning to come out of dormancy and photosynthesize, using the Sun’s [...]

In Brief: Glaciers in northeastern Utah’s Uinta Mountains began their retreat a few thousand years after the Laurentide Ice Sheet, illustrating the importance of both the position of the jet stream and local moisture sources for glacial dynamics. About 100 miles east of Salt Lake City, the Uinta Mountains of northeastern Utah rise up out [...]