Reuters AlertNet Lite - INTERVIEW-Global warming and the melting of Greenland

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INTERVIEW-Global warming and the melting of Greenland

06 Jun 2007 13:05:28 GMT
Source: Reuters

SWISS CAMP, Greenland Ice Cap, June 6 (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...

Antarctica is the sleeping giant. But it was cold so far. The peninsula that sticks out into the ocean was the only place you could see very strong warming -- it's actually the place with the strongest warming on the globe currently. If that has an effect on big ice shelves and they start to disintegrate, then the ice masses from higher elevation move into the ocean, then there is a possibility that you actually produce more fresh water, which could change the conveyor belt.

The cause of the current warming is an increase in greenhouse gasses, which is worldwide, not just in the Arctic. The only thing that could stop Greenland's melting is the ocean currents, and they are very inert. They need a lot of energy to actually make changes.

Q: Short of the conveyor belt stopping, what could reverse the warming in Greenland?

A: We had a similar warming in Greenland in the 1930s. It took about two and a half decades to get that warm, but the temperatures were almost identical as they are now. But this was a local warming around Greenland. Right now we have warming all the way down to the mid-latitudes.

How could it be reversed? That's a hard question, because if you put greenhouse gases into the atmosphere it takes a very long time to take them out. We have never had such a high carbon dioxide level in the past 500,000 years.

We cannot take CO2 out of the atmosphere, not in the amount that's currently there. It is self-regulating, yes. CO2 is taken out and put into the ocean, but it's a very slow process. If we actually start now, changing our emissions through better fuel consumption or better insulation, everything helps in that way.

We know California has grown its industry and population but its CO2 output has decreased in the last 15 years. It is possible to have an increase of the economy and population and decrease your output. Only that would help in the longer term. But the warming will continue even if we turn off all the engines today because of the memory effect in the atmosphere. It takes quite a long time.

Q: How do you view the media coverage of climate change?

A: One disappointment I would raise is if you look at the understanding of climate change by scientists -- let's be generous -- 95 percent of scientists say we understand the process and we are convinced there is global warming. The media reports it, like a lot of other stories, as 50-50. They want to always show the other side. That's good, but I'm disappointed that the media does not reflect that there is a 95-5 percent discussion. It sounds like it's 50-50. The public reads this and they can't make up their mind usually.

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Last updated:Wed Jun 6 13:07:01 2007