Shop Windows to the Universe

Ready, Set, SCIENCE!, by the National Research Council, focuses on K-8 science classsrooms. Check out the other publications in our online store, as well as classroom materials.
Icebergs floating near Cape York, Greenland
Click on image for full size
Image courtesy of Mila Zinkova, Creative Commons Attribution ShareAlike license

Greenland’s Ice Is Melting Faster

Greenland, the enormous island – the world’s largest- that sits between the Arctic and Atlantic Oceans, is almost entirely covered with ice. A massive ice sheet blankets about 80% of the land surface. As our planet warms, Greenland’s ice is melting. The ice sheet is getting thinner and the slowly flowing ice is moving towards the ocean. Recent research has found that the rate of the ice melt has been speeding up.

Earth’s warming climate means that overall Greenland looses more ice than it gains each year. The amount of ice melt during the summer of 2007 was the largest since scientists first started making satellite measurements of the ice in 1979. According to climate scientist Konrad Steffen, the amount of ice Greenland lost in 2007 was “the equivalent of two times all the ice in the Alps, or a layer of water more than one-half mile deep covering Washington, D.C." The rate of ice melt in the western part of Greenland has sped up by about 30% since 1979.

Konrad Steffen and his research team at the University of Colorado monitor Greenland’s ice in a variety of ways. From far above, satellites equipped with microwave sensors collect data that allow the team to chart the area of melt, understand how the ice sheet is thinning, and to figure out how fast the ice is moving towards the ocean. On Greenland’s ice, monitoring stations collect data every hour about ice sheet processes. Plus the team investigates the top of the ice sheet through helicopter surveys. Sophisticated cameras and a rotating laser helps the team map the volume and shape of tunnels called moulins.

Better understanding moulins, vertical tunnels through the ice that drain melt water down below the ice sheet, may be key to understanding the rate at which Greenland’s ice is diminishing. "We know the number of moulins is increasing," said Steffen. "The bigger question is how much water is reaching the bed of the ice sheet, and how quickly it gets there."

Why is the amount of water at the bottom of the ice sheet important? The melt water draining to the bottom of the ice through moulins causes the ice to slip more quickly towards the ocean - a bit like slipping on a banana peel. Outlet glaciers, the routes that ice takes towards the sea, are moving more quickly now than they were in the past. For example, a large outlet glacier on the west side of Greenland, called the Jacobshavn Glacier, has nearly doubled its speed in the last decade. The flow velocity of other glaciers has increased by up to 50% during the summer melt period.

The Arctic is warming more rapidly than other regions. For example, while Earth’s average temperature has increased by 1 degree Fahrenheit over the past century, air temperatures in Greenland have increased by about 7 degrees Fahrenheit since 1991. Because warming is more rapid in the Arctic, the impacts are much more pronounced. Greenland’s accelerating rate of ice melt is one of many major changes in the region. The amount of sea ice in the Arctic Ocean has been decreasing in recent decades, with an especially steep decline in 2007. Permafrost in Arctic tundra has been thawing rapidly too. And warming is causing changes to Arctic ecosystems.

When Greenland’s ice melts, the water is added to the ocean, causing sea level to rise. Sea level also rises when icebergs calve off a glacier into the ocean. If all the ice that is on Greenland were to melt or calve into the ocean, global sea level would rise 7.2 meters (21 feet.) Currently, melting Greenland ice increases global sea level by about 0.5 millimeters each year. If the ice melts faster, then sea level will rise faster. A better understanding of how Greenland’s ice is changing will help us understand more about how sea level will change in the future.

Last modified July 18, 2008 by Lisa Gardiner.

Shop Windows to the Universe Science Store!

Our online store includes books on science education, ranging from evolution, classroom research, and the need for science and math literacy!

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Glaciers and Ice Sheets

For a glacier to develop, the amount of snow that falls must be more than the amount of snow that melts each year. This means that glaciers are only found in places where a large amount of snow falls each...more

What is Climate?

Climate in your place on the globe is called regional climate. It is the average weather pattern in a place over more than thirty years, including the variations in seasons. To describe the regional climate...more

The Warming Arctic

In the north polar region, the climate has warmed rapidly during the past few decades. Average temperatures in the Arctic are rising twice as fast as they are elsewhere in the world. In Alaska (USA) temperatures...more

The Arctic: Earth's North Polar Region

North of the Arctic Circle (at 66.5°N latitude) you will find the Arctic Ocean surrounded by the northernmost parts of the continents of Europe, Asia, and North America. You will find the geographic North...more

Sea Ice in the Arctic and Antarctic

Sea ice is frozen seawater. It can be several meters thick and it moves over time. Although the salts in the seawater do not freeze, pockets of concentrated salty water become trapped in the sea ice when...more

Permafrost

When the ground under your feet is frozen, interesting things can happen. The land may be covered with circles, polygons, or stripes, called patterned ground, which form as the land freezes. Trees may...more

Arctic Tundra

The Arctic tundra, vast plains filled with grasses, flowers, mosses and lichen, is located north of the taiga forests in Earth’s north polar region. Like all types of tundra, this is a very cold and windy...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA