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Temperatures are dropping and the onset of the Northern Hemisphere snow season is upon us. In the Arctic region, snow is already beginning to fall and over the next few weeks, other high latitude and even some mid-latitude locations will get their first dusting. The full snow season is defined as the interval between the [...]

Preliminary results indicate that on September 10, 2010, the Arctic sea ice reached its annual minimum extent of 1.84 million square miles. This is the third lowest extent on record after the 2008 and record low 2007 seasons, and 22 percent below the 1979-2009 average minimum. This year’s melt season started late, leading to the [...]

Many of Earth’s great ice masses, which collectively form the cryosphere, are floating on ocean surfaces. There are three main collections of floating ice: the Arctic sea ice, the Antarctic ice shelves and the Antarctic sea ice. All three components have seasonal fluctuations, with the Antarctic sea ice showing the most dramatic differences between winter [...]

For about the past two million years, Earth’s climate system has been characterized by glacial cycles that last between 80,000 to 120,000 years. These cycles have long periods when the Earth cools and ice sheets build up to their maximums, followed by relatively short warming periods when the ice retreats and then “interglacial periods” like [...]

In Brief: Climate changes during the period from 15,000 to 12,000 years ago coincide with changes in small mammal communities in western North America. Earth’s ecosystems changed rapidly 15,000 to 12,000 years ago and ecosystems in the western U.S. were no exception. The retreat of the region’s alpine glaciers during this period, which during glacial [...]

By most estimates, Earth’s sea level rose by 3.5 mm per year between 1993 and 2006. About one-seventh of this sea level rise can be attributed to ice melt on one island – two to three days worth of the summertime melt water from the island could supply the New York Metropolitan area’s water needs [...]

One of Earth’s most dramatic seasonal cycles is the waxing and waning of the sea ice that surrounds Antarctica, the driest, darkest and coldest continent. At its maximum extent at the end of the Southern Hemisphere winter in September, a 6.9 million square mile expanse of ice extends from Antarctica’s shores out into the Southern [...]

Since the 1750′s, the amount of methane (CH4) in the atmosphere has increased by 250 percent. Much of this methane is emitted from lakes in northern regions. Glacial movement across the far North (north of 45 degrees) during the last ice age leveled the landscape, carved depressions in the bedrock and deposited ice that formed [...]

Earth 13,000 years ago was in the process of thawing from the coldest part of the last ice age. Then, something sudden and catastrophic happened: within a few decades, northern Europe’s average temperature dropped by 18 degrees Fahrenheit. The sudden cold period that followed is called the Younger Dryas, named after the Arctic tundra wildflower [...]

Each year, rivers originating in the surrounding mountains and forests send an average of 229 trillion gallons of freshwater into the Gulf of Alaska. The amount of water flowing into the Gulf and when most of the flow occurs affects how salty the waters in the Gulf are. How salty these waters are affects the [...]

In Brief: The area of ice mass loss on the Greenland ice sheet has been migrating northward since 2005. As large ice sheets melt and lose weight, the underlying crust “uplifts” or “rebounds” in response. Researchers have been using two key tools to monitor the rates of ice loss on the Greenland Ice Sheet: a) [...]

Glaciers have a mass balance. Glaciers lose mass by melting during the warm season (primarily the summer months) and gain mass by accumulating snow during the cold season (centered around the winter months). If a glacier accumulates more mass during the cold season than it loses during the warm season, it is said to have [...]

The energy moving in both weather systems and through the wires that power your home can be measured in watts. The Sun heats the Earth causing the fluids of the atmosphere and the oceans to move, creating the winds and currents of Earth’s climate. The vast majority of the energy in the climate system moves [...]

Snow is both a product of the weather and a weather maker. It has long been recognized that snow exhibits a cooling effect on local and regional scales. Snow reflects more sunlight than bare ground, meaning that it absorbs less energy. More snow cover also means soils stay moist for longer following the spring melting [...]

Snowfall and snow cover have direct effects on transportation, soil freeze/thaw cycles, water availability, flood frequency, water quality, wildlife, forest fires and more. Far from being just a passive product of prevailing climatic conditions, snow cover also influences climate by changing the surface albedo, the amount of solar radiation a surface reflects. The presence of [...]

When put in 2000 US dollars, freezing rain (ice storm) events in America caused an estimated 16.3 billion dollars in total losses between 1949 and 2000 due to downed power lines, downed trees, agricultural losses, transportation accidents and medical costs from injuries due to slippery conditions. Freezing rain events are most frequent in the Northeast, [...]

Ice masses maintain their own local climate through several mechanisms. One mechanism is known as the ice-albedo feedback mechanism: ice is more reflective than surrounding rock or ocean and the more reflective a surface is, the less sunlight it absorbs and the less it warms. Highly reflective ice surfaces promote the cold conditions that allow [...]

Beneath the Antarctic ice sheet lie some of Earth’s final frontiers – networks of subglacial lakes, many of which have been isolated from the atmosphere for as long as 15 million years. Outlet channels allow these lakes to periodically drain into the ocean, refill and drain again. The largest of these lakes, Lake Vostok, lies [...]

Much attention has been given to the decline of sea ice over the North Pole, which fell to a September minimum of 1.6 million square miles in 2007, about 40 percent below normal levels. On the other side of the world, the sea ice that extends from Antarctica’s continental ice sheets out over the ocean [...]

Once water is evaporated from the ocean or a moist land surface, it may spend days traveling through the air. Complicated systems of winds at different levels of the atmosphere can transport moisture (as well as other gases and dust) from the point of origin to remote locations thousands of miles away. While about 30 [...]