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A conclusion of the 4th International Polar Year

Filed under: — rasmus @ 13 June 2010 - (Español) (Italian)

This week, the “Oslo Science conference” the largest conference ever -it was claimed – was held on polar sciences at Lillestrøm, just outside Oslo. Some of the web-casts from that meeting are worth watching, and I found especially the talk by David Barber (“On Thin Ice: The Arctic and Climate Change”, video link here) both a bit alarming as well as fascinating.

Storms and snow affect sea-ice growth, since a layer of snow on top of the ice insulates against the cold atmosphere and prohibits ice growth. Winds and extra mass can lead to break-up, and the amount of multi-annual ice is lower than expected; it has decayed and ‘rotted’. A mission with the Canadian ice breaker apparently managed to break ice slabs much thicker than expected, due to weaker ice. Also more recent reversals of the Beaufort gyre, unexpected long swells, and new ice on top of clumps of old ice fooling the satellites to think there is more multi-year ice than really the case, are just part of the story. In the mean while, the sea-ice for this season from NSIDC is on a low note.

The main message that I took home from this was that the sea-ice is more important than I previously thought. It appears clearer now that it plays a role in the Arctic amplification – which clearly is really emerging.

Some claim that reduced sea-ice can explain cold winters in the northern hemisphere, but I’m not yet convinced. The cold winters are due to weak Arctic Oscillation, and hence a shift in the air masses bringing frigid polar southwards, and this air is replaced by milder air in the polar region. Hence, a shift in the wind system as well as milder temperatures may favour less Arctic sea-ice.

The Antarctic sea-ice cover has increased on average in the last 30 years, but not everywhere. Both the general increase around East Antarctica and the large decrease off West Antarctica are attributed to the ozone hole and corresponding changes in the Southern Annular Mode (SAM, or the ‘Antarctic Oscillation’), though this probably doesn’t explain what is happening in winter. There is no clear polar amplification observed over Antarctica, such as seen as in the Arctic, and one explanation for this may be that the Antarctic continent has large ice sheets with enormous thermal inertia. But ice core data suggest that there have been amplification there in the past too. Nevertheless, the Arctic is characterized by a polar ocean with retreating sea-ice in the northern hemisphere. In both cases, changing air masses and the winds are important for inter-annual to inter-decadal variations, both in explaining cold winters over Eurasia and sea-ice around Antarctica.


108 Responses to “A conclusion of the 4th International Polar Year”

  1. 51
    E. Swanson says:

    David Barber’s lecture mentions the impact of warming water on bottom melting of the multi-year sea-ice. There is also another mechanism at work, the increase in inflows of warmer waters into the Arctic Mediterranean from the North Atlantic and the Pacific. This might be the result of increased down welling of dense waters under the sea-ice during the winter months. As the sea-ice area expands, there is brine rejected in the process. This results in densification of the water below, which can sink in shallow coastal shelf areas, such as that poleward of Siberia. Any waters which sink into the depths of the Arctic Mediterranean eventually add to the overflows across the Greenland-Iceland-Scotland shelf, which separates the Arctic Mediterranean from the North Atlantic. These waters sink and produce part of the North Atlantic Deep Water, which lies just above the even denser waters produced by similar action around the Antarctic.

    The yearly cycle of sea-ice growth and decay appears to be increasing, since the minimum extent is declining faster than the maximum extent. This may result in increased production of THC waters in the Arctic Ocean. The freshening of the surface waters in the Nordic Seas could reduce the THC in that location, which would ultimately tend to bring more warm water into the Arctic and thus speed the rate of decline in the sea-ice minimum. There is a weak indication of a reduction of THC sinking in the Western Greenland Sea, which may impact the AO and thus change weather patterns. I suggest that this may have happened last winter and contributed to the colder than usual weather over Northern Europe and parts of the US.

    E. S.

  2. 52

    Why “Arctic Mediterranean?” To emphasize that the Arctic Ocean is relatively land-locked?

  3. 53
    Completely Fed Up says:

    “The yearly cycle of sea-ice growth and decay appears to be increasing, since the minimum extent is declining faster than the maximum extent.”

    The maximum extent being limited to how long and where there is no sunlight, not to the temperature (well, very much less).

    It’s why maximum sea ice extent is not an indicator of temperature, whilst minimum is.

    Maximum sea ice extent IS a good indicator of axial tilt, mind.

    Which is also an effect in the Milankovich cycle.

  4. 54
    Completely Fed Up says:

    “I actually said the amplification effects are potentially exaggerated.”

    In what way?

    “The point of my post was that GISS is the only major temperature data set that covers the Arctic”

    Not really. The Russian dataset is quite large.

    “and it is the warmest of the data sets because of the Arctic amplification effect it reports.”

    Circular reasoning: there’s an arctic amplification because the GISS shows a greater warming because it’s including the arctic which has an amplification of warming in it, which is there because the GISS shows a greater warming because…

    “It seems to me that extrapolating shoreline data 1200 km across the Arctic does precisely that kind of overestimation.”

    Unless that point you’re extrapolating is actually spatially anomalous in a cooler sense. (Why would it not be?). Therefore there’s an UNDERestimation going on there.

    There is no GISS amplification of warming. There’s an “inclusion of the Arctic increase in uncertainty”, or amplified uncertanty, but uncertainty goes both ways. NOT just warming, but cooling too.

    Please reread this post:

    http://www.realclimate.org/?comments_popup=3607#comment-177478

    It explains your issue correctly.

  5. 55
    Ray Ladbury says:

    B. Buckner,
    If trends continue, there will likely be lots of bouys where the ice used to be to measure temperatures directly.

  6. 56
    ccpo says:

    I suggest, though, that there is a negative feedback as well – melted sea ice allows more heat to escape from polar oceans..

    Huh? Are you saying the albedo effect doesn’t exist, which is nutty, or, are you acknowledging that there is a heat loss when the fall sea ice forms, which is true? If the latter, it doesn’t compensate for the heat gained by the lowered albedo, nor does it result in radiative transfer to space. The formation of the ice merely transports some heat from the water to the air, which is reflected in higher anomalous fall Arctic air temps.

    Your “the AO will save us” ain’t happening, and I see no mechanism by which it would.

  7. 57
    Completely Fed Up says:

    “Huh? Are you saying the albedo effect doesn’t exist,”

    No, he’s ignoring it because it’s devastating to his case.

  8. 58

    #56–

    I think the idea of “melted sea ice allows more heat to escape from polar oceans” is meant to refer to [assumed] heat transfers from ocean to atmosphere during what we might call “minimum season.”

    The problem is that there is no quantification of the various effects involved in this imagined scenario. How–and how much–does the ocean (assuming it is warmer than the lower atmosphere) warm the air? How much additional evaporation (with attendant heat transfers) takes place?

    The biggest questions I have are:

    1) why assume the heating is even predominantly ocean-to-atmosphere during the “minumum season?” This when air temps are elevated; why shouldn’t a good percentage of direct heat transfer in fact be in the opposite direction?

    2) To what extent can atmosphere efficiently sink/source heat from the ocean anyway, given the heat capacities of each? Seems like the atmosphere would be rather a poor “counterweight” in this sense–which brings us back to the importance of the albedo feedback again.

  9. 59

    Sanity check, please.

    I was looking at the animation of Arctic ice melt at Cyrosphere Today and felt I could actually see the swirling motion of the Beaufort Gyre. In fact, it almost felt like there were two (or that it shrank and grew), one off the north coast of Alaska, and another centered on the north pole that seemed stalled/inhibited as the ice bunched up against Greenland.

    It appeared that Greenland, Svalbard and Ostrov all formed a wall that both helped to direct the gyre, and caused the ice to lock up. It was as if it were trying to swirl the ice around, but it would all get congested and compacted with no place to go.

    I don’t know if this was just an optical illusion, or if it really happens.

    My thought was, however, that the presence of enough ice there was a key factor. I went back and looked as far back as 1980, and only 1997 and 2005 showed any gap of open sea off the coast of Ostrov, and then only a sliver at the very end of the melt season.

    My line of thinking was that if the ice melts early enough to open a noticeable gap off of the coast of Ostrov, then the “swirl” may be able to become more pronounced, and literally spill some of the ice out (path of least resistance) into the open ocean by redirecting it south into the Norwegian and Greenland seas, rather than packing it up against Greenland. This would in turn open the gap further, and thus greatly accelerate the rate of melt.

    If this is the case, then this would represent a physical (mechanical) tipping point.

    Does anyone know much about this? Or is it all just ill conceived rubbish caused by misleading Internetelligence (which is like real intelligence, except it’s available to any fool with an Internet connection)?

  10. 60

    Addendum: I know Arctic winds are supposed to affect things… perhaps it’s the wind and ocean current and not the land which locks the ice, in which case a clear path would probably not matter (because it’s not clear, the wind is still there). I should probably think about things longer before I post. More research would probably help, too…

    Maybe I could start a new approach, one where people think carefully before they post, only after educating themselves thoroughly from varied and valid sources. Perhaps I could lead the way to a new age, an age of rebirth, a Renaissance!…

    Naaaaaahhh!

    [Apologies to Steve Martin/Theodoric of York, and SNL.]

  11. 61
    E. Swanson says:

    Re: #52, Kevin McKinney

    The name “Arctic Mediterranean” is used to denote the similarity with the Mediterranean Sea. The Arctic Ocean and the Nordic Seas are connected thru the relatively deep Fram Strait. The resulting basin is separated from the North Atlantic by the ridges between Greenland and Iceland and between Iceland and Scotland. The water which sinks as part of the Thermohaline Circulation (THC) anywhere within that basin must eventually add to the overflows across the shallow sills in the Denmark Strait and the Faroe Bank Channel. These waters flow into the North Atlantic, where they tend to sink deeper into the ocean, the amount of flow increased by entrainment with surrounding water. Add in the sinking waters from the Labrador and Irminger Seas and what results is called the Atlantic Meridional Overturning Circulation (AMOC).

    E. S.

  12. 62
    B Buckner says:

    RE:#56
    The albedo effect in the Arctic is minor. When the sun is at its highest (now) the Arctic is almost entirely covered in ice. When the ice reaches its minimum in September, the sun is low in the sky and the light reflects off the ocean surface. The albedo effect would be more prominent at the edges of the ice in the northern Pacific and Atlantic where a pull back of the ice would expose the water to more direct sunlight in the summer.

  13. 63
    Completely Fed Up says:

    “The albedo effect in the Arctic is minor.”

    Have you done the calculations, BB?

  14. 64
    J. Bob says:

    #20, Tim, you might want to get more samples about Western European temperatures. Here are some anomaly plots starting with the 1659 English data going up to 1800. These included the Cen. England, DeBilt, and others from Upsalla, Berlin. Paris. Rimfrost http://www.rimfrost.no/
    is a good source for these early temps. The 1750-2008 data includes those records starting before 1750. The 1800-2008 data are those records starting prior to 1800.

    http://www.imagenerd.com/uploads/lt-temp-1650-2008-1-Rxrdy.gif
    http://www.imagenerd.com/uploads/lt-temp-1750-2008-4-EyvXd.gif
    http://www.imagenerd.com/uploads/lt-temp-1800-2008-14-9ZSv8.gif

    Using a Fourier convolution lo-pass filter of 40 years, one can get a picture of some of the secular changes going on, especially at the end points. Unfortunately we do not have ocean records back that far.

  15. 65
    Tim Joslin says:

    ccpo #56: I’m not saying “the AO will save us”. Quite the opposite, in fact. I’m saying the AMO might confuse our perception of GW. Its effect needs to be determined as a priority, so that when it enters a different phase people aren’t saying “the Arctic ice isn’t melting any more, maybe GW has gone away”, undermining political action.

    There’s virtually nothing on the AMO in the 4AR. I suggest that the next AR redresses this situation, either taking it into account or refuting the idea.

    I started investigating the AMO back in February when I saw how Professor Latif was treated in the UK media, as detailed in a post on my own blog. It didn’t seem to me that he’s obviously wrong and I’ve found nothing since to suggest that conclusion.

    I asserted that “melted sea ice allows more heat to escape from polar oceans”, which you seem to think is a crazy statement.

    How can I explain this point without being called “nutty”?

    Let’s consider the marginal case of the last km2 of ice up towards the pole. Either this bit of ice melts or it doesn’t. Compare the two cases.

    Note first that the minimum Arctic sea ice extent is in mid September, the start of winter. I don’t think the albedo effect is very powerful in winter.

    Case 1: The water under the last km2 of ice could be several degrees above freezing and still not have time to melt it right through before the start of winter. Ice insulates. Most of the heat will remain in the water all winter.

    Case 2: If the ice does melt through, though, then it’s going to refreeze, extracting all the energy that was put in to melt it. But a lot more heat will be taken out of the water than in case 1. First, we were melting freshwater, but because the water mixes we’ve now got to freeze saltwater, which requires cooling the water to a lower temperature. Second, convection will carry cold water downwards so that we have to cool a significant depth of water in order to freeze the surface. Third, we have to overcome physical effects during freezing (the same applies to areas of thinner ice that never melted in the first place). If ice cracks, vast amounts of heat escape to the bitterly cold atmosphere – I read somewhere up to 1000W/m2 – and you can end up with pressure ridges of ice 30m deep.

    A lot of weight is given to the temperature of the Arctic being warmer than usual in winter. But we need to consider the heat in the system. Yes, a higher temperature means there’s more heat at the surface, but that heat has been exported there from elsewhere. It is being radiated away. All else being equal, the planet loses more heat the higher the Arctic winter surface temperature.

    Consider this analogy. If I go out in winter in a thick jacket, but no gloves or hat, then I lose heat from my head and hands, that is, from the parts that are at a higher temperature to the touch or to a thermal imaging camera.

    Basically, Arctic warming is one way excess heat trapped by GHGs is escaping from the planet. All my previous comments on here have been trying to do is highlight the politically important point that there’s no reason to suppose Arctic warming is a linear process.

    A final point. Sure, the albedo effect reinforces the warming of Arctic waters in summer, causing more ice melt. But if more ice melts, that just means more is going to freeze in winter. Even in the first approximation (i.e. ignoring the fact that you have to take more energy out to freeze the water again than you put in to melt it), it’s a zero-sum game.

    What we should be more concerned about is decreases in the maximum ice extent (e.g. loss of the Odden ice tongue), because that indicates we’re starting to reduce the capacity of the system to lose excess heat. The minimum ice extent tells us a lot less about that.

  16. 66

    65 (Tim Joslin),

    There are few points you make that don’t jive with my understanding.

    If the ice does melt through, though, then it’s going to refreeze, extracting all the energy that was put in to melt it.

    Ice does not extract heat when it refreezes, it releases it. That is, if you have water at 1C, and air at -1C, the water drops to 0C and freezes, and the air rises to 0C (having absorbed the latent heat of fusion from the water). Of course, I’m using temperatures incorrectly and somewhat arbitrarily to make a point, but you get the drift.

    …but that heat has been exported there from elsewhere. It is being radiated away. All else being equal, the planet loses more heat the higher the Arctic winter surface temperature.

    and

    Basically, Arctic warming is one way excess heat trapped by GHGs is escaping from the planet.

    You sort of jumped tracks here. Yes, the heat is being shifted (atmosphere to ocean, or vice versa, and in H2O phase changes), but how do you jump all the way to “radiated away” and “the planet loses?” It’s no longer in the water, or air, but that doesn’t get it all the way out into space. It just moves it around within the system. You can’t defeat GHGs just by phase changes from liquids to solids and back again, or moving the heat from the equator to the poles, or vice versa. Shuffle, shuffle, shuffle, but it only leaves the planet through infrared radiation, period.

    But if more ice melts, that just means more is going to freeze in winter. Even in the first approximation (i.e. ignoring the fact that you have to take more energy out to freeze the water again than you put in to melt it), it’s a zero-sum game.

    What leads you to this conclusion? Who says “as much as melted last year must freeze this winter?” That’s an assumption without foundation, and you yourself contradict it later when you talk about the maximum extent chaning. There could easily be a situation where less re-freezes, and you have a lower maximum extent. Or more re-freezes, and you have a larger extent, but then maybe the subsequent rate of ice loss the following spring-summer-fall is so rapid that it still leaves you with a lower minimum. There is no reason to assume anything here.

    And you don’t take out more energy to freeze than you put in to melt… 1st law of thermodynamics and all that. When you freeze at the poles, you are taking the heat out of the water and putting the heat back into the atmosphere in equal measure.

    What we should be more concerned about is decreases in the maximum ice extent (e.g. loss of the Odden ice tongue), because that indicates we’re starting to reduce the capacity of the system to lose excess heat. The minimum ice extent tells us a lot less about that.

    But again, we’re not “losing” anything, it’s just moving from atmosphere to ocean or vice versa, and being tied up or released in a phase change. This part (the energy shuffling) is a zero-sum game.

    Except that if the minimum gets low enough, then there’s no more opportunity to extract heat from the atmosphere (through the melt process), and it has nothing to do except hang around to make the rest of the planet feel a little more toasty. So yes, the Arctic acts as a sort of air conditioner, absorbing excess heat by melting, and releasing heat by freezing, keeping the overall heat content of the atmosphere relatively stable (as long as there’s not more coming in than is going out, i.e. the effects of GHGs).

    What we should be concerned about is the melting of the Greenland and Antarctic ice packs, and glaciers, because this is melt that is not undergoing a subsequent re-freeze. That is, the act of melting is ice absorbing heat from the atmosphere to change into water. It holds atmospheric temperatures down by doing so (although I did the calculation once, and I don’t think it’s by much on an annual basis), until the day there is nothing left to melt, and any excess heat at that point has no place to go.. and raises global temperatures that much more.

  17. 67

    http://www.realclimate.org‘s done it once again. Superb article!

  18. 68
    ccpo says:

    Bob, thanks for that. Saved me a lot of effort.

    Tim, you’re either excited about an idea that you came up with and are not seeing the forest, is my guess. You are shooting heat exchanges at the water/air tranistion all the way through miles of atmosphere, ignoring the large body of info on colling between 1940 – 1970, ignoring the 160 year trend, etc.

    There’s no there there.

    Cheers

  19. 69

    The May NCDC numbers are out–there’s a whole lot of “warmests” going on, even as we say goodbye to El Nino for this turn of the cycle.

    http://www.ncdc.noaa.gov/sotc/?report=global

  20. 70
    Timothy Chase says:

    Kevin McKinney wrote in 69:

    The May NCDC numbers are out–there’s a whole lot of “warmests” going on, even as we say goodbye to El Nino for this turn of the cycle.

    http://www.ncdc.noaa.gov/sotc/?report=global

    Actually it is when El Nino collapses that you expect the temperature to go up. Don’t understand the exact mechanics, but roughly speaking the warm water that upwelled during the El Nino is at that point circulating to other parts of the world’s oceans. Thus the peak world temperature generally follows the peak of the El Nino by a few months. However, the peak 12-month average global temperature will be the better part of a year after the peak of the El Nino.

    And in the meantime? The monthly anomaly will rise and fall, a bit like a swing that goes forward and back, but never quite as much either way once the initial force has been removed.

    The peak anomaly for NCDC for any given month was set back in February of 1998 at 0.8288°C. A bit higher than the 0.6853°C of May 2010 or even the March 2010 anomaly of 0.7784°C but certainly well above the May 1998 value of 0.6311°C.

    And we have nearly set a new record 12-month average global temperature for NCDC. The previous record set by the period Oct 1997 – Sept 1998 at 0.6365°C as the result of the Super El Nino. Our much more modest El Nino? So far this year the 12-month average global land and ocean temperature anomalies have been 0.5649, 0.5747, 0.5971, 0.6106, 0.6236°C. Wouldn’t be particularly surprising if the June monthly anomaly puts the NCDC 12-month anomaly up over the top.

    Of course with NASA GISS we have already been breaking the 12-month records for a bit. Prior to 2010, the last 12-month record was set in Jan 2006 – Dec 2007 at 0.6217°C. For the 12-month periods ending in the months of 2010? 0.5825, 0.6050, 0.6358, 0.6567. 0.6633°C. We never managed to break the statistical tie with the peak 12-month average set back in 1998 — until March of this year. And it continues.

  21. 71
  22. 72
    Tim Joslin says:

    Bob #66: Thanks. Taking your points in order:

    1) Oops. Yeah, you’re right, that sentence about extracting energy doesn’t quite compute. I suspect I was thinking that if all the energy to melt the ice came from the air it would have to be returned to the air to refreeze the ice. But in actual fact what’s happening is:
    – heat from Arctic water which, since it can’t warm in situ under a layer of ice, must have warmed elsewhere, melts the sea-ice in summer (with some assistance from incident sunlight and air warmed elsewhere).
    – the sea then freezes over again in winter, which would indeed leave us back where we started if we assume the heat released on freezing is returned to where it came from to melt the ice. Except, as I argue in #65, the refreezing process involves cooling of the water column and the formation of briny cold deep water, i.e. removal of heat that has arrived from elsewhere by oceanic circulation. The sinking cold water draws in more (relatively) warm water to continue the process.
    – but, since the only thing colder than the water that’s freezing is the air, the actual latent heat of fusion is almost all lost, now I belatedly think about it clearly, to the atmosphere.
    The net result of the melt and refreeze process is therefore to extract heat from the Arctic waters. To labour the point, the melt and refreeze process can only happen if the ice actually melts.

    Thinking about it further, this process also occurs to a lesser extent even where the sea-ice doesn’t melt through, as it is thinned from below in summer taking heat from the water, and refreezes from above in winter, losing heat to the atmosphere. The heat flow is greater the thinner the ice. As I said, the ice is an insulating layer.

    2) Re. “jumping tracks”: maybe I should have said that what we should be most concerned about is heat in the oceans. As far as storage of heat is concerned, the atmosphere is bordering on irrelevant. Pretty much all the extra heat we manage to get out of the Arctic ocean in year x compared to year y is going to leave the planet. E.g. snow and rain may be fluffy white and wet stuffs, respectively, that come out of the sky, but they are also part of a fairly efficient mechanism for moving heat a few thousand feet up into the atmosphere from whence it can more easily be radiated away.

    This point simplifies the discussion somewhat. Basically, tropical oceans gain heat over the year and transport it N & S, and oceans at higher latitudes lose this excess heat over the year to the atmosphere and ultimately to space. My argument centres around the point that this loss of heat can happen more or less efficiently depending on the configuration of ice, in this case in the N.

    3) Annual amount of ice melting: yes, I was conscious of this assumption as I wrote. It’s a justified simplification. The change in maximum or minimum ice extent is small compared to the amount of melt and refreeze of the ice each year.

    4) Apparent violation of laws of thermodynamics: the point is that the Arctic ocean is not a closed system. In order to refreeze the surface layer, the water below has to lose heat that has arrived from elsewhere to the atmosphere as it cools and eventually freezes, as described in #65. As discussed in my point (2), once heat is in the atmosphere it can be radiated away, especially at high latitudes in winter. It can’t be if it’s in water, trapped under ice.

    I put it to you that we do “lose” energy from the planet. In terms of radiative balance, polar regions have a net loss of energy over the year; tropical regions a net gain. Energy moves from tropical to polar regions to approximately balance the equation each year.

    It’s not an exactly zero-sum game. The extent of the planet’s net gain or loss of energy over the year depends on a number of factors including the polar ice configuration (other factors are GHGs, ocean currents e.g. affected by El Nino, aerosols, surface albedo and moisture content etc).

    5) The Arctic won’t really ever export heat, because it’s colder than adjoining oceans, it can only ever import it less efficiently. But, the greater the annual fluctuation in sea-ice extent and volume, the more heat the Arctic will be able to import. This potentially sets up an oscillation in the system, as I argued in my earlier comments.

    Basically the Arctic is a cunningly designed machine to pump heat out of the North Atlantic (NA) and to a lesser extent the North Pacific (through the Bering Strait). It sucks in warm water, takes the heat out, and returns a cold deep current of water. It can’t do this so efficiently if it is clogged up with ice at the start of winter, so it gets behind on the job and the NA, in particular, warms. On the other hand, if too much of the Arctic ice melts in the summer because the NA water being drawn in is so warm, then the Arctic fridge will get ahead of itself and over some years drain so much warm water from the NA that the NA starts to cool. But that cuts off the supply of warm water and the Arctic sea-ice starts to rebuild… Hence, I suggest, the possibility of an Atlantic Multidecadal Oscillation, or AMO.

    6) Agreed. We should be concerned about loss of the Greenland and Antarctic ice-sheets.

  23. 73
    JRC says:

    I was wondering how much of a difference between albedo effect there is between ice and snow. To clarify, when I speak of ice, I’m talking about a clear ice. I could possibly see a potential for more freezing rain type events in my area. I’m asking out of curiosity. Thank you.

  24. 74

    72 (Tim Joslin),

    I put it to you that we do “lose” energy from the planet. In terms of radiative balance, polar regions have a net loss of energy over the year; tropical regions a net gain. Energy moves from tropical to polar regions to approximately balance the equation each year.

    But this energy isn’t lost by the planet as a whole, it’s just moved from tropics to poles. It’s only lost if it’s radiated into space (only!)… and that loss is primarily governed/modulated by the temperature of the planet (higher temperature = more IR) and greenhouse gases (which reflect the IR back, making it harder to escape into space).

    It’s not an exactly zero-sum game. The extent of the planet’s net gain or loss of energy over the year depends on a number of factors including the polar ice configuration (other factors are GHGs, ocean currents e.g. affected by El Nino, aerosols, surface albedo and moisture content etc).

    [See my note on El Nino’s at the end of this comment, but for now…]

    I think, for me, the heart of where the hardcore denial crowd get it wrong is that too many people get caught up in all of the complex mechanations of the globe as a very intricate, complex, interwoven series of heat pumps and sinks; troposphere, atmosphere, ocean surface, deep ocean, ocean currents, winds, phase changes, etc. all shuffling the heat from here to there to there to there.

    But this is all just moving heat around inside of the system.

    What really matters, what it really comes down to, is the radiation imbalance between the planet and space. You can talk all you want about moving heat different ways, but in the end, if more energy is coming in than is going out, the planet is warming. That’s the core, undeniable problem. Detecting that warming is hard because it is so unevenly distributed and constantly shuffled, but it’s still there if the imbalance is there, no matter how you choose to try to measure temperature, or even if you fail to properly measure it.

    So the only important factors are:

    1) Solar irradiance, which is the total amount of energy received from the sun over a period of time, and which has been proven to be fairly constant.
    2) Albedo, which reduces the effects of solar irradiance by reflecting it back out (or not, as more ice melts).
    3) GHGs, which increase the effects of solar irradiance by reflecting it back inward before it escapes (until the planet heats enough to balance radiation out with radiation in).
    4) Feedbacks of any of the forms of 2 and 3, which either counter or amplify the effects of 1, 2, 3 and 4.

    Arctic ice is of importance for two reasons, no matter how much you dissect it:

    1) It has the potential to reduce the planet’s albedo, accelerating warming.
    2) It is further evidence of a warming world.

    Everything else is important for understanding how things work, but not for the final temperature of the planet. No matter how complicated a path you can configure to move the heat around, it’s still here in one form or place or another.

    On a side note, I’ve also come to realize that the importance of El Nino and La Nina is not that El Nino’s make the planet warmer. They don’t. They actually probably cool the planet, by exposing a larger surface area of warmer waters and subsequently warmed air, which will then radiate more heat into space more efficiently. Yes, it makes the measured temperatures of the planet warmer at that time, but the planet was the exact same temperature during the preceding La Nina. But the La Nina piles up the warm waters, keeping them from radiating their heat away and being noticed, so while the planet appears cooler during a La Nina, it is actually accumulating more heat.

    Everyone should root for more El Nino’s, to help slow global warming.

    I should take the time to do the calculations, to see how much an average El Nino might slow global warming by temporarily increasing outbound radiation, except my list of to-dos is far too long already. If anyone else wants to give it a try, I’d be grateful.

  25. 75
    Tim Joslin says:

    Bob #74: I hope you don’t think I’m part of the “denial crowd”.

    I’m confused, since you realise correctly that El Nino events raise the average surface temperature, but in actual fact cool the planet, or at least cause it to warm more slowly than would otherwise be the case, in the sense of causing it to lose more heat than it would without the El Nino. Exactly the same applies when there is less Arctic ice. The more relatively warm water is exposed in a given winter, and the less ice cover there is, the more heat the planet radiates away.

    I fully appreciate that moving heat around the planet doesn’t in itself do anything to reduce or modify the long-term effects of global warming. In my previous comment I explained how heat moves to the Arctic purely in order to show how it could either be trapped under ice or, when the ice is absent, lost to the atmosphere and hence much of it radiated away.

  26. 76
    JRC says:

    I guess I found my answer here as far as a range.

    http://en.wikipedia.org/wiki/File:Albedo-e_hg.svg

    Is this a fair reflection (no pun intended) of the ranges for albedo?

  27. 77
    Anonymous Coward says:

    Bob (#74),
    The distribution of heat affects the radiation emitted. Obviously the temperature profile of the atmosphere is very important but there’s another matter to consider: the amount of radiation emitted by the surface is not exactly a function of the average surface temperature. If you have an object with two halves which have different temperatures, the radiation emitted will not be a function of t1 + t2 but of t1^4 + t2^4.

  28. 78
    Susan Anderson says:

    I think I’ve learned more plodding through all your comments than anywhere else about how the science applies. Sometimes I wish I saw more “common sense” observations, but realize if the common sense matches the theory, that’s getting close to bingo. There was a graphic of the Gulf Stream going up by Greenland, which matches the frozen European story. There’s Sphaerica’s exposition of the complicated parts of the simple truth, that unless heat leaves our atmosphere it’s still here. And others …

    I’m not a big fan of ongoing exchanges with trolls, but perhaps there are others like me who learn from the answers if they are technical and not too repetitive or contemptuous. Not that the provocation isn’t there, but allowing it to kidnap the conversation once what’s really going on has been properly explained and illustrated gets a mite boring.

    Great links, if somewhat sad.

    On a lighter note (not exactly) if any of you didn’t see this:
    http://www.nakedcapitalism.com/2010/06/rachel-maddow-rewrites-obamas-oval-office-address-on-bp.html
    I wish!

    And for anyone delving into hurricane history Chris Mooney did a good complete job in Storm World a few years back.

  29. 79

    75 (Tim Joslin),

    I see your point about more exposed water, but I think both the total surface area of the Arctic, the time period during which more water than usual is exposed (due to extended melt — and it’s only the additional area that counts, not the total area), and most importantly the relatively low temperature of the Arctic as compared to the tropics means that the radiation loss due to more ice melt is minimal as compared to something like El Nino. I suspect that factor is inconsequential as compared to the change in Albedo (which admittedly suffers from all of the same limitations).

    Again, I wish I had time to actually do the math, even back of the envelope calculations to see how the two compare. It shouldn’t be two hard. The basic question is “does 1 square meter of open water at average summer Arctic ocean surface temperature emit more or less energy in IR than is reflected by 1 square meter of ice?”… taking into account the fact that GHGs will trap some of that IR, where it has no effect on the reflected sunlight.

    [I wasn’t sure which side of the fence you were on, which is why I phrased the “denial crowd” comment so ambiguously :) ]

  30. 80

    77 (Anonymous Coward),

    I’m not sure I see your point. Can you be more clear?

  31. 81
    jyyh says:

    Back to basics: The extra energy retained in the atmosphere by the increased amount CO2 has to go somewhere. If it does not enter the arctic and other glacial features on the planet weakening and melting the ice, it will go somewhere else. Another place it may go is to the oceans and other water increasing evaporation, which will produce higher humidity on locations with more intense rains. If the energy doesn’t do that, it may go to the atmospheric circulation producing more intense winds (low or high in the atmosphere). If the energy doesn’t do that it may go to the heating of the land and top soil producing drought conditions. If the energy doesn’t do that, it may go to the increased organization of the plants, algae and cyanobacteria which are the only living things capable of diminishing the total amount of CO2 in the thermodynamic system called earth (without additional energy input). So, it seems there is some choice as to what may happen in the future: Glaciers may melt, rains may intensify, winds may intensify, droughts may intensify, or plant, algae and cyanobacterial life becomes more abundant. At least one of these has to happen. All of these but one is not good for animal life. Given that one of these has to happen, odds are that somewhere plant life suffers from worsened weather conditions. This will increase the third part of life, the organisms that are decayers of other matter in living things. So the 6th option due the higher CO2 levels in the atmosphere is the collapse of primary producers, plant feeders and predators in some areas (ecological collapse).

    Stopping the logixc here, I must go to tend the garden.

  32. 82
    Completely Fed Up says:

    “I’m confused, since you realise correctly that El Nino events raise the average surface temperature, but in actual fact cool the planet,”

    The El Nino lets more energy leave the system because there’s more IR radiation intensity at the surface where it can eventually leave for space, rather than sit in the deep ocean where it hasn’t got an escape vector (the thermohaline layer forbids).

    Rather like a lagged hot water pipe is cooler than an unlagged one but the water in the lagged hot water pipe is hotter than the water in the unlagged water pipe.

    “Exactly the same applies when there is less Arctic ice. The more relatively warm water is exposed in a given winter, and the less ice cover there is, the more heat the planet radiates away.”

    Except ice has a nearby available phase change: melting.

    Takes a lot of energy to do that, and that depends on sunlight as much as temperature. How else can ice melt when it’s still at negative tempertures?

    “I explained how heat moves to the Arctic purely in order to show how it could either be trapped under ice or”

    You didn’t explain how that heat isn’t trapped there, but melts the ice there.

    Forgetting these things while going “doesn’t this make it all so much safer and make there be no catastrophe” is how you get painted with denialism.

    It’s unskeptical ignoring of the counters to your proposal.

    Have a read of the IPCC report. It has plenty of discussion about counter proposals and probable unconsidered causes in the report.

    If you don’t know, then it would be better to ask for explanation and NOT draw a conclusion that is different from the IPCC consensus.

  33. 83
    Anonymous Coward says:

    Bob (#80),
    You said that movements of heat inside the system (Earth) don’t matter, only the radiation to and from space. But the movements of heat affect the outgoing radiation…
    I gave you an example on top of the more obvious ones alluded to in recent comments: moving heat from a hot place on the surface to a cold place on the surface lowers the amount of radiation emitted by the surface (because the radiation emitted is a function of temperature to the fourth power).

  34. 84
    Completely Fed Up says:

    “You said that movements of heat inside the system (Earth) don’t matter, only the radiation to and from space. But the movements of heat affect the outgoing radiation…”

    Yes, so those movements only matter when they move eat outside to space.

    I can move a kettle of boiling water from house to house and room to room.

    But until I pour it in a cup with some instant coffee in the bottom, I don’t get a cuppa.

    “But you have to move it to the room that has the cup in!”.

    “Yes, but that doesn’t get me a cup of coffee, does it.”

  35. 85

    83 (Anonymous Coward),

    Okay, what I didn’t understand was where you were headed with objects with two halves. You’re still not entirely clear, because you’re not specifying which hot place to which cold place you are talking about.

    Yes, some movements affect outgoing radiation by increasing the exposed surface area of warmer bodies (like El Nino), or decreasing the heat of the exposed surface area (like La Nina), but these are short lived on the relevant time scales, and episodic, so they generally balance out.

    I gave you an example on top of the more obvious ones alluded to in recent comments…

    Can you give specific examples of situations where you think the decreased outbound radiation (or “sequestered heat,” if you will) is both sizable, and long lived? In this case, I mean long lived enough to actually hold global temperatures down on a time scale relevant to the current dilemma (i.e. long enough for us to run out of fossil fuels, and then wait for the CO2 to fall out of the atmosphere, which looks to be on the order of a hundred years or many hundreds of years)? Because anything on a shorter time scale than that is actually just making things worse, by hiding the heat while the planet continues to absorb more.

  36. 86
    Anonymous Coward says:

    Bob (#85),
    I can’t answer most of your question directly because you make unwarranted assumptions. Let me clear up something first: decreased outbound radiation causes a (larger) radiative imbalance and therefore (faster) warming. It doesn’t hold temperatures down as you state. The causality is in the other direction: lower temperatures cause a decrease in the outbound radiation.
    Again, “hiding” the heat in the oceans is not the only way to cause a decrease in outbound radiation. A change in the distribution (not the amount) of heat on the surface can increase or decrease total outbound radiation as I explained earlier. You ask for an example. Due to a change in circulation, my understanding is that Greenland was warmer than usual this winter while Northwestern Europe was colder than usual. As a result, the radiation emitted by the Earth’s surface should have been a bit lower (assuming the warming near Greenland was more or less compensated by the cooling near England of course).
    Circulation changes can have much larger effects (see the hypotheses about sudden climate change in the recent paloeclimatic record or the discussion about the thermohaline circulation in AR4 for instance) and need to be taken into account which is why the pros use these complex circulation models. Circulation changes not necessarily short-lived or epidosic. You mention ENSO so please check Mike’s recent RC entry about the MWP for instance: the balance between El Nino and La Nina seems to have changed and, in some models, one mode or the other is strenghtened by global warming.
    Finally, recent papers discussed on RC have claimed that the absorption of CO2 and heat by the oceans are so finely balanced over the long run that global temperatures would remain more or less stable over many centuries after the emissions from fossil fuel stop. I’m skeptical of course but these claims aren’t totally absurd. Don’t assume that processes which “hide” the heat are short-lived or irrelevant.

  37. 87

    86 (Anonymous Coward),

    I can’t answer most of your question directly because you make unwarranted assumptions.

    ? ? ? (What assumptions?)

    I don’t think I disagree with much if any of what you said, and I suspect you are merely misunderstanding what I’m saying. I’m still confused about your point about two halves of an object emitting radiation differently (which is absolutely true, yes), only because I don’t see the point you were trying to make. Everything you said in post 86 seems to be in agreement with everything I’ve said/think.

    decreased outbound radiation causes a (larger) radiative imbalance and therefore (faster) warming. It doesn’t hold temperatures down as you state.

    This is certainly true, and I don’t think I ever said otherwise, although maybe my language was unclear because it’s important to distinguish between observed temperature, actual total system temperature, and changes in energy/heat content. I did say that increased radiation (such as due to a larger surface area of warm water during an El Nino) would hold temperatures down, as in reduce the rate of warming (not necessarily cool the planet, just warm it less quickly). La Nina does the opposite (less outbound radiation, more warming, even though the global surface temperature is measured as lower).

    A change in the distribution (not the amount) of heat on the surface can increase or decrease total outbound radiation as I explained earlier.

    Again, this seems to be a repeat of what I said (again, example is El Nino). But an El Nino lasts months to a couple of years. This is not long enough for CO2 to drop out of the atmosphere (assuming all emissions stopped on a dime), so over the long run it’s going to be balanced.

    Circulation changes can have much larger effects… Circulation changes not necessarily short-lived or epidosic. …

    Again, this is exactly what I was saying… that unless you can find something that is going to increase or decrease the outbound radiation for a very, very long time (i.e. not short-lived or episodic), then arguing about one particular mechanism gaining or losing energy is pointless. I was asking for examples of/ideas for such long term mechanisms.

    Finally, recent papers discussed on RC have claimed that the absorption of CO2 and heat by the oceans are so finely balanced over the long run that global temperatures would remain more or less stable over many centuries after the emissions from fossil fuel stop.

    Again, yes, this was my point. Unless something can bury the heat for a thousand years (e.g. sucking it down into the Great Ocean Conveyor), then phases changes, tropic to pole movement, etc. just shuffle the heat around the planet, increasing outbound radiation here, or for a time, and decreasing it there, for a time… but on average, over time, it stays about the same.

    I’m not sure where we disagree, or that we do disagree.

  38. 88
    Brian Dodge says:

    I downloaded the data from IJIS , normalized the daily numbers for each year to the peak extent for that year, and aligned the peaks. The plot shows that this year has had an anomalously large percentage rate of decline.

  39. 89
    Brian Dodge says:

    Wups – left out the link – http://www.imagenerd.com/uploads/ice_melt-fwHoy.jpg

  40. 90
    jyyh says:

    thanks Brian Dodge, it’s good to see this one too, however the maximum ice extent date is quite hard to define on some years (two closely matching peaks or a long stagnation near the maximum extent). I have not calculated it (haven’t had the time and I’m not as confident of my maths skills), but defining the maximum for each year to be somewhere in the middle of these two peaks (or long stagnation) could be more informative. As individual years are compared, the gradually steepening slope in melting (that should be happening if warming is accelerating), should become apparent and somewhat quantified.

  41. 91
    jyyh says:

    Now that I’ve done 61-day averaging on the IJIS-data, it is clear one needs to apply some solar correction to that too. This is somewhat hard to do since the polar night applies differently on different dates, but I’m certain someone can do that too.

  42. 92

    I read somewhere with interest that the sun is not strong enough to have any impact on sea ice…. Wrong….. Very wrong, Antarctic sea ice melts completely during their summer. some of it South of 70 degrees latitude, right next to a huge very albedo like glacier. Venture like a tern back to North Pole ice, Most of which is North of 70 degrees North. Only thick, very thick perennial ice acted like the Antarctic ice Glacier. Now that it is mostly gone all none melting albedo is too strong bets are off. Need I remind at Local apparent noon the sun elevation is 38.5 degrees at 75 degrees North, right now. This was powerful enough to melt the thickest ice as was in 2007. Only the clouds spare the ice from transforming to water. When its very sunny as now is the case, goodbye ice:
    http://www.weatheroffice.gc.ca/data/satellite/hrpt_dfo_nir_100.jpg

    even in March and April with outside temperatures as cold as -25 C with sun elevations far lower, there is a significant diurnal temperature effect, when at night is almost always colder than during Local Apparent Noon. Imagine now 38 degree sun unhinged by no clouds, and the ice attacked on 2 fronts, the top and the warmer sea bottom. Bye bye indeed.

  43. 93

    “Need I remind at Local apparent noon the sun elevation is 38.5 degrees at 75 degrees North, right now.”

    And if you look at the numbers, that doesn’t shave off too much energy:

    http://en.wikipedia.org/wiki/File:Water_reflectivity.jpg

    38.5 degrees elevation translates to 51.5 degrees off normal; as you can see, reflectivity at this angle varies between 0 and about .08.

    To be sure, that’s the maximum value. But see this paper on how all this nets out:

    http://www.atmos-chem-phys.net/10/777/2010/acp-10-777-2010.pdf

    (Hat tip to LouGrinzo, who posted this link on Neven’s new Arctic sea-ice blog.)

    LG quotes this bit from the abstract:

    A disappearance of the Arctic ice cap during the sunlit period of the year would radically reduce the local albedo and cause an annually averaged 19.7 Wm−2 increase in absorbed solar flux at the Arctic Ocean surface, or equivalently an annually averaged 0.55 Wm−2 increase on the planetary scale. In the clear-sky scenario these numbers increase to 34.9 and 0.97 Wm−2 , respectively.

    Wayne has said elsewhere that he expects a lot of clear skies in the Arctic this summer due to the emerging La Nina–hence a very large melt event.

    Don’t know if that’s what will happen or not–having had my sea-ice expectations dashed a couple of times–but early indications don’t seem especially promising for the ice to hold up. It looks pretty fragile, if you look at MODIS imagery, or even Cryosphere Today for that matter, and temps continue to be quite elevated even after the fading of the El Nino. (Do I recall correctly that temps lag by about 6 months? That would take us well through the melt season.)

    For example, the 6/18/10 UAH value was +1.38 C. That’s relative, not to the baseline, but to 2009’s date, which was already one of the highest values in the UAH record! I don’t know how it relates to 1998, since the available graph begins 1998 with August values (due to satellite changeover, I think.) But the value is higher than the peak temps–typically occurring about a month from now–for every year except 2009 and 2005.

    We’re (still) living in interesting times. . .

  44. 94
    Neven says:

    Another quote from the paper Lou posted is more relevant at this point in time, I think:

    We used the same methodology to calculate the effect of
    the forecasted September total sea-ice meltdown. Even if in
    all other months sea ice keeps its climatological extent, if we
    remove it for September, the annual absorbed solar flux increases
    by 0.32Wm−2, if we average spatially over the Arctic.
    The local effect of a September ice-free Arctic Ocean
    is eight times smaller than the enhanced greenhouse effect
    (2.5Wm−2).

    It will take quite some time for the Arctic sea ice to disappear during ‘the sunlit period of the year’.

  45. 95
    Tiredofitall says:

    Good god! Have you lot actually sat back and read all of your comments? It’s just supposition upon assumption upon tiny changes in poorly measured data upon tiny time scales upon vagueness upon the complete refusal to concede that man’s contribution to a trace gas is a tiny percentage i.e. our ‘contribution’ to the earth’s atmosphere is minute. Before you all sound off about GHGs, make sure you take water vapour into account ( which you AGW zealots love to ignore)

    [Response: Oh please…. Have you actually read anything we’ve written on these subjects? Start here. – gavin]

  46. 96

    #95–

    Au contraire, “Tired,” the water vapor feedback is an integral part of the mainstream science. Do try to keep up with what you attempt to criticize.

    And if by “tiny percentage” you mean about 35%–390/290 = 1.3448–then yes, you’re right, we’ve contributed “a tiny percentage” to the atmospheric CO2 burden.

    Too bad it isn’t a good deal tinier–we’d all be a good deal safer if it were.

  47. 97
    Ray Ladbury says:

    Tiredofitall, Dude, why don’t you go to the peer-reviewed literature and find something that supports your currently unsupported opinions. Go ahead. We’ll wait.

  48. 98

    I would like suggest RC to keep up high profiling the Arctic ice melt, as its sea ice extent anomaly is about to reach 2008 and 2009’s 2 months earlier!

    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.anomaly.arctic.png

    I expected this, and I also expected huge apathy from the rest of the world, especially about the plight of Arctic sea ice (and its unique ecosystems). Many further web spotlights would help accelerate the melting of this lethargy. I know there is a few sites out there dedicated for this , keep it up guys!

    Some comments are really good like 93 Kevin, and Neven as well. But RC needs to follow this really closely.

  49. 99
    Richard C says:

    Tiredofitall – Was that your attempt at fifteen minutes of fame?

  50. 100
    Neven says:

    “But RC needs to follow this really closely.”

    I agree with Wayne, but at the same time I realize that after the shock of 2007 and the expectation of even greater losses of Arctic sea ice in subsequent years (Death Spiral) that didn’t come about, polar scientists are a bit more careful with their predictions.

    You see this reflected in the first SEARCH Sea Ice Outlook: http://neven1.typepad.com/blog/2010/06/search-september-sea-ice-outlook-june-report.html

    But I expect they will go all out if this rate of melt continues unabated.

    BTW, I have just finished a blog post with a really nice animation (if I say so myself) of the eastern part of the Beaufort Sea that gives a great insight in the Arctic situation: http://neven1.typepad.com/blog/2010/06/animation-3-beaufort-sea.html


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