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News You Can’t Use About Arctic Ice Climate Change

  • Published: July 8th, 2011
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Michael D. Lemonick By

Credit: istockphoto

Every month the National Snow and Ice Data Center (NSIDC) issues a report on how much of the Arctic Ocean and surrounding waterways are covered in ice, and whenever that happens — most notably in summer, when the ice melts back to reveal open water — people like me feel the urge to write a news story about it. That's especially true when the ice coverage seems ominously low. So when the NSIDC put out its June report yesterday, announcing the second-lowest ice coverage in the 32-year satellite record, many of us gave in to our primal journalistic urges. The climate blogger Joe Romm, for example, using one of his patented apocalyptic metaphors, wrote about the Arctic Death Spiral.

Stripped of it's horror-movie title, the post (and other recent commentaries, including one by my colleague Andrew Freedman at The Washington Post) make a number of valid and important points. First, a progressive decline in summer ice cover has long been predicted as a consequence of overall global warming, due to a process called "Arctic amplification." The idea is simple: in a warming world, ice melts back in summer, replacing white, light-reflecting ice with darker, light-absorbing sea water. The water warms up, so that refreezing in winter comes a bit later, and produces ice that's a bit thinner. The next summer, this thinner ice, along with rising air temperatures, creates more melting, which exposes more ocean, and so on.

Other factors influence year-to-year melting, including ocean currents, cloud cover and wind patterns, so the "death spiral" might well take a pause, or even reverse a tiny bit, in a given year. But over decades, the ice should steadily decline, until at some point, decades from now, the Arctic Ocean should be mostly ice-free in late summer.

In the real world, this is exactly what satellite observations have shown.

According to the National Snow and Ice Data Center, Arctic sea ice extent last month was the second lowest on record for the month of June, falling behind only 2010. Credit: NSIDC.

As you can see in the chart above, the biggest meltback happened in 2007 — the only month where June ice was lower than this year (it rebounded slightly after that year, but not much, which nicely illustrates the "other factors" point above). So it well might be that 2011 will be a new record year for open water in the Arctic, or that it may be a second-worst year.

Or maybe it won't. Once again I invoke other factors. If the weather up north does something unexpected, we could end up with more ice this coming September than everyone expects. Or we could end up with less. At this point, nobody really knows for certain. It's kind of like hurricane-season forecasts, or presidential-race handicapping. Who the front-runner is for the 2012 Republican nomination (this is about the presidential race, just to be clear) is absolutely meaningless at this point — yet politicial pundits can't help filling newspaper columns and hours of airtime talking about it. What this summer's hurricane season would look like from the perspective of last winter, when the first forecasts came out, was not quite as meaningless. But it was hardly anything to rely on.

Seen in that context, last months' ice extent isn't a hugely meaningful fact. It won't be hugely meaningful either, if the ice situation is worse in September than it was in 2007, or worse than last year, or slightly better. On the one hand, reporters like me try to explain to our readers that climate change is an overall trend, played out over many decades, and that a single year that's warmer than the year before, or cooler, doesn't mean a blessed thing. 

And on the other hand, we sometimes make a huge deal when a given year is warmer or less icy than the year before — while deriding climate skeptics if they should trumpet a cooler than average year, or make a fuss about the fact that Arctic ice hasn't yet reached the lows of 2007.

It's all a bunch of noise, in both the statistical sense and the more conventional sense as well. 

What matters (yes, I'm repeating itself) is the trend over years — and the trend has been toward an increasingly warmer Arctic, at least since 1979, just as climate modelers predicted. There's absolutely no reason, based on theory or models or the experience of the last three decades, to expect this trend to change. 

And that, rather than the ice report from last month or next month or the entire summer season, is the important thing to focus on. 

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Comments

By Byron Smith (Edinburgh)
on July 8th, 2011

The point of writing stories on the state of Arctic sea ice is (as I’m sure you’re aware) to keep our attention on this part of the world that is changing faster than anywhere else, despite humanity’s relative absence from the scene. It is a powerful illustration of a changing climate. While you are right that from a scientific point of view a particular year’s melt only really is noteworthy as part of a longer term trend, from a communication standpoint it is a peg on which to hang a story. As long as the story explains the importance of the trend (as yours does, and Joe Romm nearly always does), then I think it is quite excusable to post stories about the current melt season.

By the way, is there a reason you chose sea ice extent for your graph, rather than, say, volume, which is declining much faster?

By mdbrock (springfield/missouri/65804)
on July 8th, 2011

I’m afraid we will still have to be shown in Missouri before we completely dismantle the fossil fuel economy which our state depends upon.  You might want to consult Climatedepot.com for an alternate viewpoint.

By mlemonick
on July 9th, 2011

Byron Smith, I acknowledge your point about using Arctic sea ice to call attention, and as you clearly realize, that’s just what I’ve done here. What I’m trying to do is present a little context, and to remind people of the equally important point that if the meltback isn’t steadily greater every year—or the global temperature doesn’t rise on a steadily upward curve—that people don’t jump to the common-sensical but incorrect conclusion that this somehow refutes the idea of human-induced climate change.

Speaking of which..I also tried to make the point that it’s intellectually dishonest to pick the anomalously warm year of 1998 as the baseline for gauging rising temperatures in recent years—just as it would be to pick the significantly cooler year of 1999 or 1997. It’s dishonest to pick ANY single year, since as I just mentioned above, nobody has every suggested that EVERY year will be warmer than the previous year. It’s much more legitimate to take averages of five or ten years. And in fact, every decade since the 1970’s has been warmer than the previous one. Or, if you have a compulsion about 1998, the decade 1998-2008 was warmer than any decade since 1968-1978.

It’s perfectly legitimate to demand evidence for scientific assertions, especially if they imply that some significant action might need to be taken. The question is, how much evidence do you need before you’ll consider yourself “shown.” Most people who have actually studied the data think it’s convincing. Some will probably never be convinced no matter what. I’ve been to climatedepot.org for the alternate view. There’s some good information there. There’s also, in my opinion, some bad information.

By CHICAREE (SEAL ROCK OREGON 97376)
on July 9th, 2011

Its been 55 million years ago that the Arctic was ice free.  That should chill anyone at the thought of what that will do to our global climate.  Anyone notice the weather patterns have been off the charts 2010 and 2011.  World wide just not your back yard.  This is a global program and with 7 billion people on this planet there is going to be a lot of pain.

By William Hoy (Bailey, CO 80421)
on July 10th, 2011

Open sea was found at the North Pole in 1926. In a couple of the early years of the 1940s the “northwest passage” was open to navigation. The bottom line is that the facts are two thin to support the extreme claims of the warmists.

By mlemonick
on July 10th, 2011

If by “the extreme claims of the ‘warmists’” you mean the claim that ice coverage has been progressively going down since the 1970’s, you should probably look at the chart again. Open water at the North Pole (which has happened many times since 1926) is not relevant to the question fo total ice coverage. And a couple of unusually ice-free years in the 1940’s are by themselves meaningless. In order to show a trend in climate, you need to look at several decades in a row of measurements. Kind of like what’s in the chart.

By Todd Arbetter (Alexandria, VA 22307)
on July 11th, 2011

Ice extent is half the story. Ice area and ice type (age) make a more complete picture. Consider only the Arctic Ocean, not anything outside Bering Strait or south of 80 N in the Atlantic. Every winter the Arctic Ocean will be completely covered by ice—99.9%, accounting for leads and open water (which won’t stay open long). Every summer it will melt back. The record low has been reset in 1996, 2002, 2005, and 2007, and could be again in 2011. That doesn’t include 2008, 2009, and 2010 which were higher than 2007 but much lower than 2005 (the previous low—2007 not only broke the record but broke the mold).

There have been warm periods before, as late as the 1950s. But what sets the 2000s apart is that the makeup of the ice has changed. Before the 1990s, most of the ice was 3 years and older, meaning it was thicker, stronger, and more resistant to melt. Sea ice changes fundamentally after it survives one summer. It becomes opaque, rough, and has probably been crunched, smashed, and piled up on top of itself. Two more years of that and you’ve got the thick ice everybody thinks of. Some multiyear ice melts every year. But it used to be replaced and things were in balance.

In the 1990s things started to change. The winds changed, and a lot of ice was blown down into the Atlantic. But not enough ice in the Arctic survived to take its place. The pack became more and more made up of first year ice, meaning ice that has formed since last summer and hasn’t lasted through the next. This ice is clearer, smoother, weaker, and more prone to melt. In a normal summer, half of it won’t survive. In a warm summer (relatively speaking—all it takes is a few degrees), all of it will melt.

We’ve had a lot of warm summers and few cold ones lately. The multiyear ice that disappeared in the 1990s and 2000s has not come back. The seasonal ice (first year ice that doesn’t survive) makes up more of the Arctic Ocean, meaning more of it will melt every summer. Thinner ice. Younger ice. Lower ice extent.

What would it take to reverse this? A lot of cold summers in a row. Is that likely?

Say you need 3 years to make multiyear ice. (Second-year ice exists in and of itself, but forget about it for now.)

If there were a 50/50 chance of a warm or cold summer, you’d only have a 1 in 8 chance of having 3 in a row (12%).
If you made it 33% (warm/normal/cold), you’re down to 1 in 27 (4%). But it’s not even money; the odds favor warming.

In the scientific world, there is little debate. In the real world, everything is political and a lot of good names have been sullied for the sake of a few more dollars made. It’s much harder to prove something than to deny it.

By Agres
on July 11th, 2011

9 years ago, main stream climate science did not consider the rapid decline of sea ice which we are now experiencing plausible.  Anybody that talked about such rapid declines in sea ice got shouted down as “alarmist”.  They did not want to see our data or methods.  If it was not consistent with the community general circulation models (GCM).  The GCM said we would have sea ice for 60 years, and only well after that would major changes in atmospheric circulation occur. They did not want to hear anything else.  Prior to 2007, it was the conventional wisdom of mainstream climate science.

While mainstream climate science must now acknowledge Arctic sea ice loss, they have not yet acknowledged the follow on effects to Arctic sea ice loss.  These include albedo feedbacks, and more moisture in the atmosphere over the Arctic seas.  These will result in rapid changes to atmospheric circulation.

Even mainstream climate science has understated AGW.

By Adam (Cambridge, MA 02139)
on July 13th, 2011

@mdbrock, didn’t y’all just have record Missouri river flood season within the last month, breaching levees and swamping farmland in a “1000-year flood”?  And what about the 500-year flood in 2008?  Or the 100-year flood in 1993?  How much more “show me” do you want?

Everybody always grossly exaggerates the cost of reducing pollution.  For example, SO2 causes acid rain, so the Clean Air Act established incentives to cut its emission dramatically.  Industry jumped up and down screaming that it would cost $1500/ton to abate SO2 emissions.  The EPA estimated $750/ton.  The final cost?  $200/ton.  [William Reilly, “The EPA’s Cost Underruns.” Washington Post, Oct. 14, 2003.]  Why?  Because people respond to economic incentives by developing new technologies and changing the way they do things.

Now industry is jumping up and down screaming about mercury, when more than a third of our coal-fired power plants have no pollution controls at all, spewing mercury and causing significant measurable health impacts.  And now here you are crying about reducing your fossil fuel use.  Unless you want to see St. Louis under water—along with the southern 1/3 of Florida under water—you’re going to have to “show me” what other options y’all have cooked up for dealing with climate change.

By L J Geoffrion (Lansing MI 48911)
on August 2nd, 2011

I’ve been looking for articles on the wider impacts of an ice free arctic, specifically, on the change in sun-earth energy imbalance once the ice is melted.  Energy always flows from a warmer object toward a colder object. An ice cube at 32 degrees F absorbs energy from air that has a temperature warmer than freezing.  Hansen talks about this, but I haven’t seen anything giving estimates about latent heat transfer once the ice is melted—that is, once the ice is melted, there will be “freed-up” sun energy.  How much?  What will the impacts of that be, beyond the decreased albedo?

I think that we’ll see a big jump in earth temp, like flipping a switch.

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