What exactly is polar amplification and why does it matter?

As climate science predicts, the Arctic is warming faster than the rest of the globe (see NSIDC: Arctic melt passes the point of no return, “We hate to say we told you so, but we did”). This is often called polar amplification (PA).


I wanted to do a post on PA for two reasons. First, “there are no permanent weather stations in the Arctic Ocean, the place on Earth that has been warming fastest,” as New Scientist explained (see here and here). “The UK’s Hadley Centre record simply excludes this area, whereas the NASA version assumes its surface temperature is the same as that of the nearest land-based stations.”

Thus contrary to what the global warming deniers say about the recent temperature record, it is almost certainly the case that the planet has warmed up more this decade than NASA says, and especially more than the UK’s Hadley Center says.

So that’s why I see the NASA temperature record as more accurate, which puts 2005 as the warmest year on record, with a rough tie for second between 2007 and 1998. Sorry, deniers, not bloody much evidence for recent “global cooling.”

Second, PA is a tad more complicated — and more interesting — than the popular explanation has it.

As RealClimate notes in their useful discussion, “Polar amplification is thought to result primarily from positive feedbacks from the retreat of ice and snow.” Indeed, the popular explanation is that warming melts highly reflective white ice and snow, which is replaced by the dark blue sea or dark land, both of which absorb far more sunlight and hence far more solar energy.

But in fact Arctic warming is amplified for several additional synergistic reasons, which are worth knowing. As the International Arctic Science Committee (IASC) explains in their 2004 report, Impacts of a Warming Arctic (see figure here):

  • In the Arctic, compared to lower latitudes, “more of the extra trapped energy goes into warming rather than evaporation.”
  • In the Arctic, “the atmospheric layer that has to warm in order to warm the surface is shallower.”
  • So, when the sea ice retreats, the “solar heat absorbed by the oceans in summer is more easily transferred to the atmosphere in winter.”

[And as one climate scientist explained to me, it can get incredibly cold above thick ice, but it can’t get much colder than freezing above open water.]

All this leads to more snow and ice melting, further decreasing Earth’s reflectivity (albedo), causing more heating, which the thinner arctic atmosphere spreads more quickly over the entire polar region, and so on and on.

And that in turn threatens a cascade of effects. As the scientists at The International Polar Year note, this could “speed up melting of the Greenland ice sheet, accelerating the rise in sea levels,” and “Permafrost melting could also accelerate during rapid Arctic sea-ice loss due to an amplification of Arctic land warming 3.5 times greater than secular 21st century climate trends” (see “Tundra 4: Permafrost loss linked to Arctic sea ice loss“).

Yet the destruction of a significant fraction of the permafrost must be avoided at all cost, since the tundra feedback, coupled with the climate-carbon-cycle feedbacks that the IPCC models, could easily take us to the unmitigated catastrophe of 1000 ppm (see Tundra, Part 2: The point of no return).

That’s why polar amplification is important.


16 Responses to What exactly is polar amplification and why does it matter?

  1. Harrier says:

    It all seems to suggest the need to act NOW, but right now the political will seems lacking in the places where it really matters. The U.S. finally has a president who takes climate change seriously, but the Congress is going to impede efforts to reduce emissions.

    We would almost need a global dictator who believes in the dangers of climate change. That seems like the only way to make the necessary changes before it’s too late.

  2. Sasparilla says:

    I think, Harrier, that you are correct – we need to act now (really 8 years ago). Congress, specifically the Senate, will get in the way of a climate bill that delivers what we need (Coal and Oil black Dems doing the deed there). As Joe mentioned before, depending on a US congress climate bill to save us is the wrong approach (we still need one, but it isn’t the primary thing we need right now).

    For the moment, Obama has all the tools in his hands that he needs to get the boat – at least in the US – turned in the right direction, basically the EPA regulating CO2 and preventing further Coal plants from being built, the admin goosing clean energy generating technologies, industries and enablers (smart grid) and maybe go get serious with China about this as well. He can do all that, and for the most part, is on his way.

    There’s still hope, he can still do alot without the Senate, but the curtain (to try and meet 2.0C / 450ppm) on this isn’t going to remain up for long – we can only hope he takes this stuff really seriously as the news is getting darker by the week.

  3. DB says:

    Joe, would you want to comment on the paper from Lean and Rind from last year? In particular, Figure 3d and paragraph 14 where they talk about more heating at mid-latitudes than at high latitudes.

    “Contrary to recent assessments based on theoretical models the anthropogenic warming estimated directly from the historical observations is more pronounced between 45°S and 50°N than at higher latitudes. This is the approximate inverse of the model-simulated anthropogenic plus natural temperature trends in IPCC….”

  4. papertiger says:

    A climate dictator. YES. Why didn’t you think of it sooner?

    I mean if if you would have just come out and said what you wanted right at the beginning, think of all the time you would have saved us.

    All Hail Ceasar Obama. Emperor of the sky, water, and earth.

    Kind of like the beginning of “300”.

    I know which side I’m on. Get me some of those painted on abs, a spear, and a helmet.

  5. It may be easier to change the minds of the public than to sway the Senate directly. Massive education programs on TV etc. If enough of the public gets, it there will be pressure put on the Senate. If as many citizens agreed with AGW theory as even the 80% of scientists who agreee, according to a recent poll, then there would be marches on Washington and demonstrations like we haven’t seen since the 60s.
    Having the public agree by 97%, like the poll said active climate scientists do, is probably a little much to hope for.

  6. Gail says:

    Joe, this is the message, it’s brilliant:

    a CASCADE of effects.

    Forget feedback loops and tipping points.

    The CASCADE of effects sums it up for even the most STUPID.

  7. Sam Carmalt says:

    There is no question that an ice-free Arctic Ocean will have profound climatic effects. But the political problems with making drastic changes in CO2 output reflect an underlying reality – that the world economy has a great deal of inertia.

    Completely replacing the energy from all mined hydrocarbons with other energy sources will take considerable time. Even if a world dictator were to embark on such a project today, by the time we built all the electric cars, established all the renewable energy plants (solar farms, turbine farms, whatever) it would still require decades to complete.

    While rapid deployment of non-carbon energy should be done, we also need to realistically plan for the changes that are now inevitable. Like any planning, we don’t know exactly what the future will be (one speculation is that the increased evaporation from an ice-free Arctic actually causes another ice age within the next few centuries). But the likelihood is that we will need not only to relocate millions of subsistance farmers in Bangledesh, but also develop new cities in the developed world as places like London become unsustainable with higher sea levels.

    The investment in electric cars may only be profitable if politicians tax carbon in one way or another. An investment in something that will help our society to cope with the change is more sensible. The obvious example is that rather than rebuild New Orleans, we should spend that money relocating New Orleans’ port capacity to a site that can survive the coming changes.

    My point is that we shouldn’t be approaching these problems defensively. Yes, we’ve been foolish. Yes we should stop being foolish as quickly as possible. But we need to look at how we can positively move forward. As the old Chinese wisdom has it – we live in interesting times.

  8. Jan says:

    I just looked at the NASA temperature index [ ] and could use some help interpreting.

    It shows a -25 global mean in 1880, and in 2005 it’s at 62. Does that mean the global average temperature increased .87 degrees C for that period?

    And if that’s not a stupid question, then how about this one — what is the zero baseline of this chart? I mean, it shows -25 from what? Or plus 62 from what?


  9. Jan says:

    Oops — looked a little closer and found the base period of 1951-1980. So, I’ll revise my stupid question and ask why that particular base period?


  10. David B. Benson says:

    Jan — GLOBAL Land-Ocean Temperature Index in .01 C base period: 1951-1980

    First note the units are hundredths of a degree Celcius. What is presented are the anomalies from the base period average; a typical convention in meteorology.

  11. papertiger says:

    So if some recalcitrant countries, like say China and India, tell our eventual climate overlord to take his climate saving edicts and go stuff himself (or herself), would that be grounds for invasion? Imbargo? Blockade?

  12. Martyn says:

    A similar warming occurred in the 1930-1940 period. This cannot be blamed on the reasons mentioned in the above article. The principal heating mode of the polar parts of the planet is by heat transfer from the tropics by weather systems and oceanic circulations. The solar contribution is secondary. The heat transfer rate is not constant. One key phenomena responsible for modulating heat transfer to the arctic is the Atlantic multidecadal oscillation. By coincidence this was in the peak of its warm phase (maximum heat transfer rate) in the 1930-1940 and 1995 onwards to the present day (strong peak in 2005-2006).
    Putting out alarmist articles which ignore key climatic variables is irresponsible and misleading.

    Other factors ommited include:
    Pacific decadal oscillation
    Soot on ice albedo effects
    solar wind variations, which are concentrated at the magnetic poles of the earth, by the earth’s magnetic field lines, and expand / contract the atmosphere

  13. D says:

    Heat transfer doesn’t measures the amount of heat produced by global warming, it does only show the heat circulation impacts. The ice cap is the place where all the heat ends, and troubles too. Other regions are shielded by this cap. Do you think cryosphere in 1930-1940 was as it is actually? Do you believe the ice layers showed you that they have ever melt down before? I suggest you to take a look onto “Arctic Sea Ice Conditions, Part II: June 4, 2009”

    by Tenney Naumer, June 4, 2009

  14. D says:

    The ice cap absorbs all anomalies, because is the most cold depressed region, you can see the oceans are yet cold or warmer, but the matter is that the ice cap has all responsabilities over this circuit.

  15. D says:

    “It is a critical part of our Earth’s system,” said Dr Ferraccioli. “If the whole ice sheet collapsed, sea levels would rise by 60m.”

    “There’s been a lot of climate change over the last 14 million years,” Dr Siegert said. “And what we can say about this place in the middle of the Antarctic is that ………………..nothing has changed………………..”