Arctic Ice Cover Headed for a Record Low

Arctic sea ice extent on 19 August 2012 (orange line shows the 1979-2000 median) (Image: NSIDC)

Ice cover in the Arctic looks headed for a record low this summer.

Host Marco Werman speaks with The World’s environment editor Peter Thomson about what’s going on up there and what it might mean for the rest of the world.

There’s a striking new map up on the website of the National Snow and Ice Data Center today.

I’m looking at it right now and you can too, at the world dot org…

The map shows a blob of white surrounded by a sea of blue ringed by an orange line.

The white blob represents the size of the Arctic ice cap as of yesterday.

The orange line shows the median size of that same ice cap on the same date from 1979 to 2000.

And the blue in between is the difference, where the ice cap has been replaced by an area of open ocean bigger than Alaska, Texas and California combined.

It’s a snapshot of how quickly things are changing in the Arctic and in particular how much ice has been lost this year.

The World’s environment editor Peter Thomson is in the studio with me. Peter, experts are describing what’s going on in the Arctic this year as “unprecedented” and “record breaking.” What’s going on?

THOMSON: Well, like you said, it’s really striking, Marco. The ice cover as of yesterday is more than 30 percent smaller than that late 20th century average for the same date. It’s almost 10% below the previous record low for the date, set back in 2007. And it’s likely headed for an all-time low this year, at least a record as long as we’ve been keeping records.

As for what’s going on, in two simple words, it’s global warming. Scientists say there’s just no doubt about it. They’ve run all kinds of computer models looking at every conceivable factor, and nothing explains this rapid disappearance of summer ice in the Arctic other than the rise in global temperatures due to carbon dioxide pollution in the atmosphere.

WERMAN: So, we’ve been hearing a lot about rising sea levels due to global warming. Is all this melting ice going to contribute to that?

THOMSON: Well actually it’s not, I mean at least not directly. The Arctic ice cap is different from most of the ice in Antarctica and Greenland, in that it’s already floating, which means that when it melts it doesn’t have much effect on overall sea levels.

But what’s got scientists concerned is that it does have really important indirect impacts on sea levels.

The big thing is what they call the “albedo effect,” which is another way of saying how much solar radiation the ice and water reflect or absorb. And the difference is striking. It turns out that in the Arctic, ice reflects about 80% of solar radiation, but the dark open ocean water absorbs 90% of it . So instead of sending all that heat back into space, the open ocean where the ice used to be is absorbing it and warming up.

And that can affect sea levels in a number of important ways. As the water warms up, it expands, and it will have a modest impact on sea levels. And then over time, the water transfers some of its heat to the atmosphere. That warms up the air and can help melt ice in places like Greenland. And then there’s the growing likelihood that warming sea water is essentially helping to melt Greenland’s glaciers from below, which in turn is speeding up the flow of ice into the sea…. And that also raises sea levels.

WERMAN: So what about life in the Arctic? How is this ice loss affecting people and wildlife up there?

THOMSON: Well one of the most immediate impacts, Marco, is on creatures that depend on the ice for hunting, which includes both polar bears and people. And that changing albedo effect I mentioned is helping to warm the air up there, which in turn is causing permafrost to thaw out. That leads to all kinds of problems for local ecosystems and human communities.

But it’s important to remember that Arctic communities aren’t the only ones who’ll be affected by this. Some scientists refer to the Arctic as “the world’s refrigerator,” and as it warms up, that’s going to effect weather all around the world. In fact, Marco, there’s some evidence that changes in the Arctic could already be affecting weather today—this summer—including perhaps the big drought and that record heat here in the US this summer. Of course the whole climate system is enormously complex, it’s hard to draw a direct connection, but it seems likely that what’s going on up there is affecting what we’re experiencing down here.

WERMAN: Now the last big UN report on climate change, back in 2007, predicted we’d see an entirely ice-free Arctic some summer by around the year 2100. So take this news of ice melt today and put that in context of those predictions.

THOMSON: Well, it’s changed. A lot. After the record warm summer of 2007 scientists moved that estimate up to somewhere between 2030 and 2040. There’s no consensus estimate now, but one scientist at a major British polar research center told our colleagues at the BBC last week that he thinks we may see at least our first ice-free day in the Arctic for by the end of this decade. Eighty years sooner than we thought just a few years ago.

WERMAN: Extraordinary. The World’s environment editor Peter Thomson. Thanks very much.

THOMSON: Thanks, Marco.