Radio Script
2005

Scientists say ice caps in the Canadian Arctic are melting. (Courtesy NASA.)

Canada's Shrinking Ice Caps
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INTRO: When it comes to rising sea levels caused by a warmer global climate, our first thoughts might be of places like Greenland and Antarctica, where much of the world's freshwater is locked within massive ice sheets. But scientists are just as concerned about the role of much smaller ice caps and glaciers in places like northern Canada. Doug Schneider has more in this week's Arctic Science Journeys Radio.

STORY: Around the planet, melting glaciers and ice caps are causing sea levels to rise. According to NASA, global sea levels could rise as much as 16 inches over the next century. And while much attention has been paid to places like Greenland and Antarctica, where huge ice sheets contain most of the world's fresh water, scientists also are concerned about much smaller ice caps and glaciers in places like Alaska, Patagonia, and Canada. NASA scientist Waleed Abdalati has been busy monitoring the loss of ice within Canada's ice caps.

Waleed Abdalati (NASA).

ABDALATI: "What we were after was to try to understand just how much the ice caps in Canada have changed and what, if any, amount they've been contributing to sea level.

In 1995 and again in 2000, Abdalati and colleagues used a small plane equipped with a high-tech laser altimeter to measure elevation changes of ice caps and glaciers in the Queen Elizabeth Islands of northeast Canada. They also collected temperature and precipitation data from weather stations in the area, and used several decades of direct measurements of ice growth and shrinkage on certain ice caps and glaciers to arrive at their findings.

Abdalati says researchers discovered that most of the ice caps and glaciers had changed little or became thicker at higher elevations, but nearly all had become thinner at lower elevations.

ABDALATI: "So we basically found that they're all shrinking near the edges. Some of the southern ice caps are shrinking all over the place, and at a pretty substantial rate.

	Scientists measured elevation changes in Canada's ice caps in 1995 and again in 2000. (Courtesy NASA.) Click map to see larger image.

In the big picture of global sea level rise, the amount of fresh water in Canada's ice caps and glaciers is actually quite small. In fact, Canada has only about 58,000 square miles of ice caps and glaciers, an area roughly the size of Illinois. In contrast, Greenland has about two million square miles of ice, while Antarctica has 13.5 million square miles. Such large ice caps react slowly to warming temperatures. But Abdalati says Canada's smaller ice caps and glaciers reacted quickly as temperatures increased, something he says may have a more immediate effect on global sea levels.

ABDALATI: "Despite that fact that there is not that much ice up there compared to Greenland and Antarctica, we think what it is contributing to sea level is significant. Where it derives its significance, though, is that it is closer to the melting point—it responds more quickly than the larger ice sheets. And so these small ice masses really matter in the near term.

While Canada's melting ice caps and glaciers do not by themselves contribute much to the overall rise in sea levels, Abdalati says Canada's contributions are important when taken together with melting occurring elsewhere around the globe.

ABDALATI: "Patagonia contributed about one-tenth of a millimeter (per year) toward sea level rise during the 1990s. Alaska glaciers contributed about a quarter of a millimeter per year, and Canada is a little under a tenth of a millimeter, it's about .07. These sound like small numbers but they add up.

Exactly why Canada's ice caps and glaciers are melting is a complicated question. Ice in the southern Canadian Archipelago is melting faster—perhaps twice as fast—as ice in the north. Abdalati says that may just be a natural continuation of melting that began at the end of the so-called Little Ice Age in 1850. The region also experienced a warm spell in the 1990s. But Abdalati says local climate changes as well as human activities that burn fossil fuels are likely also having an impact.

Thanks to the following individual for help preparing this script:

Dr. Waleed Abdalati
Cryospheric Sciences Branch
NASA Goddard Space Flight Center
Greenbelt, Maryland 20771
Phone: 301-614-5696
Email: waleed@icesat2.gsfc.nasa.gov
Profile: http://neptune.gsfc.nasa.gov/STAFF/brianc/icehead.html

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Related websites

NASA Feature: Canada's Shrinking Ice Caps

Elevation changes of ice caps in the Canadian Arctic Archipelago (abstract), Journal of Geophysical Research, vol. 109, 2004

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