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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 [...]

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 [...]

Rainfall records from the central United States confirm the old adage that “when it rains, it pours.” While days with at least “moderately heavy” precipitation  ?  precipitation totals exceeding  0.5 inches  ?  account for only 25 percent of all days when it rains, more than 70 percent of the total rain volume falls during moderately [...]

The Yoshino Cherry Trees that surround the Tidal Basin in Washington, DC were a gift from Mayor Yukio Ozaki of Tokyo City to signify friendship between the United States and Japan. 2012 marks the 100th anniversary of their arrival. The cherry blossoms also signify the arrival of spring. Whereas in many other plant species the [...]

The Northeast United States has experienced a particularly mild 2011-2012 winter, with the region’s average January temperature 4.7 degrees Fahrenheit above normal. Vermont was the warm spot, coming in at 6.2 degrees Fahrenheit above normal. This mild winter, however, appears to be part of a longer-term, 50-year trend of warming winter temperatures. The average winter [...]

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 [...]

Discussions of climate and climate variability often focus on temperature trends at the Earth’s surface, which is where humans spend most of their time. But the atmosphere holds onto little energy compared to the oceans – the top few feet of the ocean holds as much heat as the entire atmosphere above it! Transfers and [...]

Temperatures have warmed by an average of two degrees Fahrenheit over Earth’s land surface and 0.6 degrees Fahrenheit over the oceans over the past 50 years. These temperature changes have been accompanied by changes in precipitation and seasonal cycles, including lengthening of the growing/frost-free season in temperate and high latitudes. Together, these factors related to [...]

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 [...]

Commercial airline flights spend most the time in the lower reaches of the stratosphere, which is the second layer of the atmosphere beginning at five to six miles up in the air. The air in the stratosphere is thin and cold, making it inhospitable, but it is also less turbulent than the air in the [...]

The Earth holds more heat today than it did in 1950 and the lion’s share of this heat has been absorbed by the world’s oceans. Water has a higher specific heat than air or land surfaces, meaning that it takes more energy to raise the temperature of a certain amount (say, a pound) of water [...]

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 [...]

Each year the United States pumps about 28 cubic miles of water out its groundwater aquifers – natural underground storage areas – for irrigation, drinking water, industrial purposes, etc. While about 84.6 percent of these withdrawals are recharged to the aquifers through natural recharge (primarily rainfall) or artificial recharge (recharge to the groundwater from human [...]

Changes in climate are fundamentally about changes in the amount of energy in the air and water circulating around us. While most discussions of climate trends focus on the air temperature taken at the Earth’s surface, this is only one measure of the amount of energy in the air, let alone the climate system as [...]

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 the air around you are organic aerosols – substances based on carbon-hydrogen bonds that are light enough to be suspended in the atmosphere for days or weeks. How much organic aerosol mass is in the air has direct implications for air quality and human health, as well as for climate and weather. Organic aerosols [...]

Earth does not orbit the Sun in a perfect circle. Instead, like all the other planets, Earth’s orbit is eccentric, meaning that it moves in a “stretched out” or elliptical pattern. The difference between the perihelion, the point of an orbit when a planet is closest to the sun, and the aphelion, the point of [...]

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 [...]