Global warming and the melting of Greenland

SWISS CAMP, Greenland Ice Cap (Reuters) - Dr. Konrad Steffen is the director of University of Colorado at Boulder's Cooperative Institute for Research in Environmental Sciences and a veteran researcher of Arctic climate. He discussed the accelerating melting of Greenland's ice cap and its effects on global ocean levels in an interview with Reuters on May 18 at his field research camp.

Q: Let's start by describing your research here at Swiss Camp.

A: We want to measure the climate over longer term to find out how it is interacting with the ice masses. Warmer temperatures in spring and fall made the melt period in Greenland much longer. Therefore we see more and more melt water from the ice sheet flowing out into the ocean and decreasing the reflection of the sun. We have seen that the total melt area over the last 30 years increased by 30 percent.

Q: How far along are scientists in understanding ice sheet dynamics and their effect on global ocean levels?

A: One effect is the melting of the ice sheet. Another effect is the dynamic response of the ice sheet, and this is quite a new observation. In the past we all assumed the ice sheet was moving at constant speed toward the ice edge. The big glacier here, Jakobshavn Isbrae, had a velocity of 6-7 km per year into the fjord up to 1995. Suddenly, this glacier retreated in the fjord, but by 2002-2003 its speed had doubled. This is a very large volume of ice that moves into the ocean.

Q: Did the last Intergovernmental Panel on Climate Change report underestimate the forecast for the rise in ocean levels?

A: I think it definitely underestimated. We complained heavily before it was released and that's why they added a few lines that if there is a dynamic response of ice sheets the upper uncertainty might be higher. We can model melt but we cannot model the dynamics. How can you actually set an uncertainty band that small if you don't understand a major process that produces now so much melt water?

Q: Could Greenland's meltdown have an effect on the conveyor belt of ocean currents?

A: The way we understand this from the past, we had abrupt climate changes that happened when huge water masses were collected on ice sheets and were flushed out at once, way bigger than what we can produce now on Greenland. The theory is open. Can we produce enough fresh water to change the conveyor belt? The present situation is we doubt it. It is unlikely that we have an abrupt climate change due to the ice loss of Greenland alone. If Antarctica is reacting faster...