?We?re Radically Changing the Nature of the Arctic?
In a recent review paper, researchers show that Arctic temperatures in the late 20th century, which were the warmest in four centuries, have been accompanied by a variety of other environmental changes. Marc Serreze, co-author of the report answers Scitizen?s questions.
In your research on Arctic sea ice [1], you found that ice levels decreased in 2006 by large amounts. Can you give us more details about your findings?
I think what it’s really telling us is that this decline that we’ve seen in the Arctic sea ice covers starting back at least in 1979 since we’ve had good satellite records, and it appears much longer, is not at this point just a feature of inter-annual variability, a feature of natural variability; what we’re starting to see is a longer term change that can only be explained by the fact that the Arctic is strongly warming, at least in part due to the effects of greenhouse gases. So, it’s something that has us really concerned at this point.
Figure 1: September 2006 sea ice extent. This image shows the average sea ice extent for the month of September; the magenta line indicates the average September sea ice extent from 1979 to 2000. 2006 had the second-lowest average September sea ice extent on record. This image is from the NSIDC Sea Ice In
What could be the impacts of this ice loss?
The impacts are manifold, certainly for the people and animals that live there it’s a problem. We know for example that polar bears are starting to have a hard time of it, because they depend on that sea ice for their livelihood. People who live there are starting to feel these effects: For example, people who live there can’t get out to the ice, say to hunt things like seals or polar bears. There’s also growing problems of coastal erosion, there are actually villages in coastal Alaska and Siberia that are having to be moved because the coast is eroding away, and the reason for that is because if that sea ice starts to draw back from the shore, all of a sudden winds associated with storms have all of this cold water they can blow over and so that creates big waves.
These are sort of examples of the effects up there of the people and animals that live there, but the larger concern is how the effects in the Arctic are going to be felt over say, the rest of the Northern Hemisphere, over parts of North America, like Canada. The issue is here, the Arctic and the rest of the climate system are linked very tightly together. Now, we’re radically changing the nature of the Arctic by getting rid of this highly reflective sea ice, if we do that, we’re going to see that manifested in larger scale changes in the atmospheric circulation.
Average air temperatures across most of the Arctic Ocean from January 2006 to August 2006 were about 2 degrees to 7 degrees Fahrenheit warmer than the long-term average across the region over the past 50 years. Why is this?
We can argue that part of this force is due natural variability; like anywhere in the United States you might have a run of particularly warm winters or particularly cool winters for example—that’s natural variability. But this warming in the Arctic is something that’s been going on for a long time now. Again, it’s telling us that the system is really starting to change. Part of what we’re seeing now is an effect of the greenhouse gases. Now we know that 2005 was also a very warm year, you may remember that in terms of the global average, 2005 was the warmest year on record for the globe as a whole, or tied, depending on the data set that you look at. But if you look where that extreme warming occurred, where the biggest warming—you look no further than the Arctic. That’s where it occurred. That whole pattern has occurred now, from January to July 2006. So again, natural variability can contribute to these changes, but this extreme warming we’ve seen in the Arctic recently, it appears to be something more at this point. It’s not just something that we can explain away by natural variability. It seems that something’s hitting on that system, that something is greenhouse gases.
A study issued last week by the European Space Agency showed that the "ozone hole" over Antarctica this year has matched a record size. Do we have the same situation in the Arctic?
Well, fortunately in the Arctic, in terms of ozone we’re a little better off. The Arctic and the Antarctic are rather different in terms of their atmospheric circulation. What happens in the Arctic is that it’s considerably warmer than the Antarctic, and as a result, these processes that contribute to ozone loss are not as extreme, not nearly as extreme in the Arctic as we see in the Antarctic—that is not to say we don’t have them there, we’ve seen evidence of what we call “mini ozone holes” developing in the Arctic. Hopefully things are starting to recover now because of the Kyoto Protocols.
As you did mention, 2005 was the hottest year of the last 12000 years a very warm year. James Hansen, who is Director of the NASA Goddard Institute, said the same thing showed in a recent paper [2] that 2005 was possibly the warmest year since 1880 and that it is conceivable that mean temperatures now are around the same level as in the Early Holocene (see comment #1 and our previous interview). What do you foresee for the climate of the Arctic region?
I see things going in a downward spiral. We might lose the Arctic sea ice cover in summer, maybe around the year 2060, maybe a little later, it depends on how things pan out. In the lifetime of some of our children, we’ll find the Arctic to be a radically different place. One with much less ice cover, and of course, this is going to have ramifications on the rest of the planet. So, I’m not too hopeful with where things stand right now; we’re seeing these radical changes in the Arctic now, it appears that they’re going to continue and get worse in the future.
Mark Serreze, thank you.
[1] Serreze M., Francis J., Climatic Change, vol 76, 241 (June, 2006)
[2] Hansen J. et al., Proceedings of the National Academy of Sciences,103, 14288 (September 26, 2006)
Mark Serreze is Research Professor at Boulder's National Snow and Ice Data Center.
Interview by Thanh Tam Candice Vu.
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It's not the Kyoto Protocol for CFCs, it's the Montreal Protocol and subsequent amendments.
The statement that 2005 was the warmest year in 12,000 years cannot be supported and was not what was claimed in Hansen et al. recently. 2005 was possibly the warmest year since 1880 (though the differences between 1998 and 2005 depend on the analsysis), and we have some reason to think that the globe was not more than about 1 deg or so warmer in the Early Holocene than in the pre-industrial. Thus given the ~1 deg warming since then, it is conceivable that mean temepratures now are around the same level as then. But we do not have the calibrated annual mean temperatures records that far back that would allow the direct comparison to be made. Given another 1 deg warming, that will be on stronger grounds, but at this point it is premature.