Scientists with the National Aeronautics and Space Administration are flying over the shrinking Arctic ice cap this summer in an effort to determine just how much the melting ice is contributing to the rise of sea level worldwide.

NASA is using a Twin Otter plane to study ice caps including the Penny and Barnes caps on Baffin Island, the Devon Island ice cap and Agassiz on Ellesmere Island.

"The Canadian Arctic actually has the largest amount of ice on the planet outside of Greenland and Antarctica, so it's an obvious place to try and understand how much water is going from there," said Martin Sharpe, a professor at the University of Alberta.

Scientists are beginning to realize more attention needs to be paid to glaciers and ice sheets in the Canadian Arctic in calculating the global rise in sea level.

The plane is equipped with an ice-penetrating radar to measure its thickness, and a laser altimeter that determines whether the elevation of the ice surface is changing.

"A large amount of our attention is focused on Greenland but the Canadian work was something I got very interested in," said Waleed Abdalati of NASA's Goddard Space Flight Center.

"Because these smaller ice masses are a little more sensitive to climate in the near term, they're no less important."

A study released earlier this year showed the amount of ice dumped into the ocean by glaciers in Greenland has almost doubled in the last five years.

Greenland contains enough ice to raise the world's oceans by seven metres, Abdalati says. But in the short term, he added, smaller ice masses could actually send more water into the ocean.

"The goal is really to figure out how much these ice masses are contributing to sea-level change," he said.

"Sea level has been going up about 1.8 millimetres a year for the last 50 to 100 years, and it's been going up about three millimetres a year for the last 12 or so years. "While that doesn't sound like much, over time it's quite significant."

Change occurring rapidly

NASA will compare this study with other airborne surveys done in 1995 and 2000.

Sharpe said both aerial surveys and research on the ground are needed to find out how much Canada's ice is contributing to the rise in sea level.

He said it's becoming clearer that when it comes to ice sheets and glaciers, things are changing more rapidly than previously believed.

The first half of the field season will be spent in Canada repeating the measurements from the two earlier surveys.

They will then go to Greenland to set up weather stations and global positioning equipment to see how fast ice is moving and to monitor weather conditions.