Greenland’s extraordinary summer #3: new record melt year, and summer’s not over yet

Greenland’s amazing summer continues, with news today that the ice sheet has already set a new record for surface melting — with four weeks of the melt season still to run. The ice sheet surpassed the previous record year, 2010, on August 8th. Marco Tedesco of the City College of New York said:

“With more yet to come in August, this year’s overall melting will fall way above the old records. That’s a goliath year – the greatest melt since satellite recording began in 1979.”

Tedesco and his team calculate the duration and extent of melt over the ice sheet, using satellite data to develop a ‘cumulative melting index’. The index is defined as the number of days when melting occurs multiplied by the total area subject to melting, and is a measure of how much melting has occurred in a season that normally runs from June to September. As the chart below demonstrates, by August 8th the melt was already well ahead of 2010.

TedescoSMI2012

So far this year Greenland has experienced extreme melt in virtually every corner of the ice sheet, and especially at high altitudes. When summer’s over, and the research teams ponder the data they’ve gathered on the ice, it seems pretty clear that there are going to be some interesting figures to consider, with consequences for everyone with beachfront property… Follow Tedesco’s work, and that of other teams working on Greenland on his Greenland Melting site.

28 thoughts on “Greenland’s extraordinary summer #3: new record melt year, and summer’s not over yet”

  1. 2012 – the year Denial became completely untenable.

    What everyone needs to remember is that, given the lag in impact of CO2 currently being pumped into the atmosphere, we are already locked in to decades more of this no matter what we do now – and if we don’t do anything now we are locked in to a future that’s almost unimaginable.

    It’s real, it’s now, and you can’t hide from it.

    Cheerfully rushing headlong into a world of unknown unknowns because, you know, cheap flights, I love my Prado, and it’s my right to set my air-conditioner at 26C in winter, is no great testament to our species’ intelligence. It’s like we’re collectively failing the greatest IQ test we’ve ever been set – the one with the most dreadfully real consequences, at that…

    1. The dreaded climate commitment. As I said in my post about sea ice, it’s possible that we could not only lose the summer sea ice during the 30 year climate commitment, but the winter ice too. That would mean hyper-melt for Greenland…

      2. While I think suggestion of the disappearance of Arctic winter sea ice before later century is preposterous, I think a good case can be made for a far above forecast melting of the Greenland icecap over the next few decades. With the combination of the disappearance of late summer sea ice lowering Arctic ocean albedo around Greenland (more solar absorption)+ the lower albedo from the increased water melt over Greenland itself (more solar absorption)+ the reduction of the icecap altitude caused simply by the disappearance of the ice (higher temperatures of lower altitude air) I think it can be argued that a runaway icecap melt might just be possible.
        All that though still doesn’t get rid of Arctic sea surface winter temperatures lower than those in the Baltic today.

        1. Preposterous? Still haven’t done the sums, have you Andrew… 😉

          Heat is accumulating up North, and it ain’t going to stop doing so. Once the multi-year sea ice is gone for good, there is no “buffer”. The only question is how much heat can be lost over an Arctic winter that starts with open ocean. That, divided by the amount of heat accumulating per annum, will determine how long it takes.

          I totally agree with you about Greenland. Scientists have been working on the physical constraints on mass loss, but I’d guess they weren’t considering melt over the whole thing for half a year at a time.

          1. I suspect you’re the one who hasn’t done the math.

            For water to freeze from zero C it needs to lose 334J/g

            For water to freeze from 10 C it needs to lose 375J/g

            For water to freeze from 20 C it needs to lose 417J/g
            (please excuse not allowing for salinity)

            Just how warm are you expecting the Arctic to get?

            1. The current numbers (Cryosat-2, see this post) suggest that the excess of heat arriving is sufficient to melt about 900 km3 per annum. That’s a lot of heat.

              Once the sea ice buffer goes, that heat will go into warming the ocean, delaying the onset of freeze. As I said above, the timing depends on the size of future heat excesses arriving in the north (are they going to get smaller? I think that unlikely), versus the “cooling potential” of an Arctic winter. IIRC, around 15,000 km3 of ice forms each winter. Unless there’s a huge negative feedback, you can divide a number of that order of magnitude by 900 (or larger) to set your timeline.

              This is all back of the envelope stuff, but research suggests that the Arctic is stable only with permanent ice or open ocean. Intermediate states are not stable.

            2. I have actually read that post,. See this comment:
              http://hot-topic.co.nz/pump-up-the-volume-before-the-ice-is-gone/#comment-33613

              Unless there’s a huge negative feedback, you can divide a number of that order of magnitude by 900 (or larger) to set your timeline.

              Believe it or not the, even with all the ice gone, the Arctic ocean won’t store all the energy it receives throughout the summer, like other bodies of water … other objects on Earth … everything else in the known universe other than black holes, it’ll continuously radiate the energy it receives.

            3. You’re missing the point. The heat required to melt 900 km3 of ice is the net heat excess,the bottom line of the Arctic heat budget, not just one element. See this 2010 post for a fuller discussion, and this helpful comment which points to work showing the instability of a seasonally ice-free Arctic.

            5. As I pointed out in comments in the other post, 900km^3 isn’t much when spread out over the Arctic ocean, when spread out over the area of the winter sea ice it’s a layer of ice just 6cm thick.

              As the Arctic Ocean warms through the summer it’ll lose temperature at a faster rate than it does now in the autumn, so we’ll see a more rapid cooling than we do now. So as we see now, the ice will reform with only a modest delay.

              Also, in addition to losing much of that extra heat in the autumn, the Arctic ocean simply will not warm much above zero because of the presence of the Greenland icecap and run-off from it, and Greenland can lose 1000km^3 for nearly 3000 years before that icecap is gone.

            6. It is possible that an open ocean will lose heat faster than ice-covered ocean, but you can’t escape the basic heat budget. A big negative feedback – if it exists, which is by no means certain – only lengthens the time to total ice loss.

              Your point about Greenland is just hand-waving. Arguments from incredulity don’t cut it, sorry.

            7. It is possible that an open ocean will lose heat faster than ice-covered ocean,

              POSSIBLE?!
              you can bet your last dollar on it.

              but you can’t escape the basic heat budget

              I don’t need to, you haven’t done a heat budget.

          2. Aargh. You’re still missing the point. That 900 km3 volume is is the bottom line of the heat budget, because that is the current annual volume loss.

            And if open ocean loses heat faster in winter (which I agree it will, because ice is an insulator), you also need to factor in the albedo effect, which will act in the opposite direction.

            As I said: read the paper linked. Modelling demonstrates that seasonally ice free conditions are not sustainable long term. We are now in a transition to a year round ice-free Arctic ocean. The only question is how long it takes.

            1. Did you read this in the paper AD linked to?

              perennially ice-free Arctic Ocean conditions occur in 2 of the model simulations after CO2 quadrupling.

              You’re making such a basic mistake you’ll be too embarrassed to admit it.

              What you’re doing is extrapolating a current disequilibrium into the future, failing to recognize that, without a powerful positive feedback working, climate changes will eventually establish a new warmer equilibrium, you’re taking the 900km^3 and adding it year on year, assuming no greater heat loss despite the warmer temperatures. You’d be doing exactly the same thing you would be doing if you claimed the temperature of the Earth will be 27 degrees warmer in a thousand years (2.7 degrees/century times 10) even if GHG concentrations were to remain constant at todays levels for that thousand years.

            2. Sorry, Andrew, but I really think you need to think again about this. We know that the climate system is currently shipping more heat into Arctic than is being lost over winter. Equilibrium can only be reached at the point where heat lost over winter equals total heat gained over the year. Even if atmospheric CO2 were stabilised tomorrow, global equilibrium would take 30 years, so it’s perfectly reasonable to assume that the current imbalance will continue. Given that CO2 isn’t going to stabilise any time soon, it’s also reasonable to think the heat excess will continue to increase, at least until we reach stabilisation (+30yrs).

              Open ocean will cool faster, yes, but it will also absorb more incident solar radiation during summer. The balance between the two remains debatable. The paper AD references discusses that balance, and finds some evidence of rapid transitions in a few model runs. On the other hand, it used old modelling, which significantly understated current sea ice loss. Even the AR5 modelling understates current losses (see NSIDC recent update for evidence), and multi- model means tend to obscure actual loss trajectories and threshold behaviour (see Bitz et al 2008 for a discussion post the 2007 season).

              Is there a negative feedback? Yes. Is it big enough to offset heat accumulating? Perhaps, in the short term. But eventually the combined effect of an increasing heat excess and albedo will flip the system into a totally ice-free state. How long that takes remains to be seen, but I reckon it will be a lot shorter than most people think.

              And your Greenland stuff just doesn’t make sense, sorry.

            3. Sigh.
              Even in the middle of the Arctic summer the sun is too low in the sky to do the amount of warming you imagine.

              I asked you earlier Just how warm are you expecting the Arctic to get?

              Perhaps you should have a crack at answering that.

              You claim that my “Greenland stuff just doesn’t make sense”.

              Tell me the science for that assertion.

              I’ll go out on a limb and argue that the Arctic will always be colder than the equator, with a steady climb in temperature between the two, so if you’re going to claim a far warmer Arctic environment, one so warm in the autumn as to stop winter sea ice forming, you’ll also have to argue substantially warmer ocean temperatures at lower latitudes.

              Go for it.

            4. The point about albedo is the difference between sea ice and open ocean, which is large. Don’t forget that the sun shines 24 hours a day in summer up there. The albedo effect starts small, because maximum ice loss occurs in late summer when the sun is low, but increases as the retreat in other seasons increases. Take a look at the SST anomalies around the Arctic ocean at the moment. Where the ice retreated in early summer, that water is warm.

              How hot will it get? Depends on a lot of things, like when and if we restrain carbon emissions, when we reach stabilisation and at what level, as well as how the system responds to the forcings on the way to a new equilibrium. We do know, however, that there have been extended periods when the Arctic was ice free all year round, and palms grew in Greenland. Can we avoid that? I have to hope so…

              Greenland melting will put most of its fresh water into the North Atlantic and Baffin Bay. Most Arctic freshening at the moment comes from the big Siberian and Canadian rivers. I agree that significant freshening could make it easier for ice to form, but given that open ocean is prone to increased storminess and therefore increased turbulent mixing, I doubt it will be significant. I suspect the only way that Greenland cold supply a negative feedback would be if it can dump enough freshwater to put a cap on the North Atlantic thermohaline circulation, and thereby change ocean heat flows enough to offset the current heat budget surplus (which is atmospheric and well as oceanic). By the time its doing that, even if it were possible, I think the sea ice might be long gone…

    1. Wow, I think I’ll have to by that to find out exactly what techo-vegans are, and with a recommendation from Mike himself what could possibly go wrong? 🙂

      1. Uh; sorry if I’ve undermined your release strategy – in my defence, it did come up in the Hot Tweets!

        Actually I’ve started reading and have just arrived in the Galapagos…

        1. My release strategy is straightforward. Get all the various editions in distribution, and then shout about it. That’s be after the print-on-demand paperback’s finalised – next month. But Amazon accounts for 70% of all ebook sales, so a bit of noise now can only help. Thanks!

  4. Pingback: Another Week of GW News – August 19, 2012 – A Few Things Ill Considered

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