The polar amplification asymmetry: role of Antarctic surface height

ant1 I apologise for breaking into the stream of politics for some science: Temperatures in the Arctic are increasing around three times as fast as the global average, yet the pace of warming has been much slower at Earth’s other pole. A new study, just published in Earth System Dynamics, suggests the difference might – in part – be down to the great heights of Antarctica’s land surface. The article is The polar amplification asymmetry: role of Antarctic surface height by Marc Salzmann. And since it's open-access I'm sure they won't mind me copying from their abstract:

Previous studies have attributed an overall weaker (or slower) polar amplification in Antarctica compared to the Arctic to a weaker Antarctic surface albedo feedback and also to more efficient ocean heat uptake in the Southern Ocean in combination with Antarctic ozone depletion. Here, the role of the Antarctic surface height for meridional heat transport and local radiative feedbacks, including the surface albedo feedback, was investigated based on CO2-doubling experiments in a low-resolution coupled climate model. When Antarctica was assumed to be flat, the north–south asymmetry of the zonal mean top of the atmosphere radiation budget was notably reduced... between 24 and 80%... of the polar amplification asymmetry was explained by the difference in surface height, but... might to some extent also depend on model uncertainties.

So there you go. I'll assume you've read the (open access) paper. And you get the idea from the image I've cut-n-pasted: under 2xCO24, the Arctic is hardly affected by flattening Antarctica but Antarctica warms much more. However, although this isn't unbelievable, it kinda goes against what I thought I knew - which is to say, the conventional explanation that they quote -, so I should look for some flaw in it. As should you! Don't take anything for granted. Ideally you'd do that by carefully reading the paper and pondering it's arguements, but life is too short so I'll leave that to you; I'll just do some drive-bys1.

ant2 As the abstract hints, this is not a sooper-dooper hi-rez model, and they give some evidence of not fully trusting it. I'm not going to quibble any details, but see this second pic I've inlined. It is the zonal average response, over 600 years vertical time. And you'll see two odd things. One in the control runs, which I'll come back to in a moment, and the second in the 2xCO2 runs.

And that is, that the warming in the Antarctic is greater than the warming in the Arctic by about the time of, oh, year 130. By bizarre chance, the first inlined pic is from years 80-109. Had they drawn the same pic for year 570-599, it would have looked very different and (dare I say) rather less convincing. Their explanation for this is THC shutdown, which as they say simpler models are rather more prone to. Well actually they say The weaker Arctic warming in the middle of the 2 × CO2 base run (Fig. 13b) is an indication of a slowing of the ocean’s meridional overturning circulation (MOC). Such a slowdown has often been found in CO2 perturbation experiments, and it tended to be stronger in low-resolution, low-complexity models compared to state-of-the-art highresolution models. Since the CESM was run at a low resolution in this study, this finding should also not be overinterpreted. From that I deduce that they didn't carefully look through all the diagnostics to verify MOC slowdown, but it's a reasonable guess. Anyway, the point that MS doesn't then link to is the polar see-saw (that's my pic!) and it would be natural to suppose that a (relative) Arctic cooling would lead to Antarctic warming. And it is possible (though I admit to not having fully joined the dots) that this is (part of) their enhanced Antarctic warming.

You might also wonder about the spin-up. Coupled models generally require some, and it looks like MS was a bit careless in this regard: It should be noted that Antarctic warming relative to the respective control run (Fig. 14a) was stronger in the flat AA than in the base model setup throughout almost the entire 600-year period. However, even though the temperature in the flat AA control run stabilized after a moderate initial warming and even though the temperature evolution from the control run was subtracted in this analysis, it cannot be completely ruled out that this moderate initial warming could have also played a role in the later development in the 2 × CO2 flat AA run. Therefore, in retrospect2, starting the flat AA 2 × CO2 run from a separate long flat AA spinup run and prescribing a more realistic gradual increase of the CO2 concentration, which would allow the inspection of the first decades of the CO2 perturbation experiments, would have been better.

The last point, which I've now come back to, is that despite the "even though the temperature in the flat AA control run stabilized after a moderate initial warming", I can't see it. You'd expect some decades of warming in the Antarctic in the control run as heat is advected in as the continent is suddenly flattened. But no; at least, as I say, I can't see it.

Anyway, there you go. I enjoyed writing that. Rip me to shreds3.


1. At one point, we had a policy against drive-by reviews. Because the thick-as-pigshit management thought that having problems with your code pointed out by people who were too busy to review all your code was bad, because the darling snowflakes sometimes got offended.

2. I read that "in retrospect" as "bollocks, the referees noticed it".

3. In memory of the Rude Mechanicals

4. Note: these are instantaneous-doubling CO2 experiments, which I thought had largely gone out of fashion, as they are somewhat less realistic that the steady-increase type.


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There'd be an expected difference between a land surface and a mostly-all-water surface. But I think most of the difference between poles is because the flow of the oceans is routed directly through (and caused by) the arctic. As any globe can show you, the water is free to circulate around Antarctica unimpeded, so the water near the continent is relatively unmixed and unaffected by the great Atlantic-Pacific Ocean currents.

Just from the lapse rate Antarctica is going to be more than 10 -15 C cooler than the Arctic. On top of that the thick ice layer has a ton of thermal inertia, so on the whole idea is not out of bounds

By Eli Rabett (not verified) on 20 May 2017 #permalink

Some ancient ice ages (Ordovician) had high CO2 but lots of vertical IIRC.

According to the paper (Figures 6 and 8) lapse rate feedback in the Arctic and Antarctic is positive. Can anyone explain why this is, as it's not obvious to me (although I'm going through a phase of discovering that I don't understand things that are obvious in retrospect ;-) )

By ...and Then Th… (not verified) on 21 May 2017 #permalink

I thought I'd posted a comment about lapse rate feedback, but it seems to have disappeared. I hadn't realised that lapse rate feedback was expected to be positive at the poles (learn something new every day). A positive lapse rate feedback means a smaller temperature change at altitude, than at the surface, so it doesn't seem all that surprising that the Antarctic is warming more slowly. I may still, however, be missing something obvious.

[I don't know why but you seem to be on moderation. I'll see if I can fix that... -W]

By ...and Then Th… (not verified) on 21 May 2017 #permalink…

Improbable as such a large rise might sound, something similar may have already happened, and recently enough that it is still lodged in collective memory.

In the 19th century, ethnographers realized that virtually every old civilization had some kind of flood myth in its literature.

In the Epic of Gilgamesh, waters so overwhelm the mortals that the gods grow frightened, too. In India's version, Lord Vishnu warns a man to take refuge in a boat, carrying seeds. In the Bible, God orders Noah to carry two of every living creature on his ark.

"I don't think the biblical deluge is just a fairy tale," said Terence J. Hughes, a retired University of Maine glaciologist living in South Dakota. "I think some kind of major flood happened all over the world, and it left an indelible imprint on the collective memory of mankind that got preserved in these stories."

That flooding would have occurred at the end of the last ice age.

Ice ages occur when wobbles in Earth's orbit change the distribution of sunlight, allowing huge ice sheets to build up, mainly in the Northern Hemisphere. At the peak of the last ice age, about 50,000 years ago, the ice sheets grew so large and locked up so much of the world's water that the sea level fell by an estimated 400 feet.

Beginning perhaps 25,000 years ago, after the orbit shifted again, the ice sheets began to melt and the sea level began to rise. Over several thousand years, coastlines receded inland by as much as a hundred miles.

Human civilization did not yet exist, but early societies of hunters and gatherers lived along most of the world's shorelines, and they would have watched the inundation claim their lands....
----end excerpt----

So what news from Doggerland?

By Hank Roberts (not verified) on 22 May 2017 #permalink

F**** polar bears one just shat on my face

By Trevor tits mcgee (not verified) on 22 May 2017 #permalink

“The massive ice sheet and the mountains below prevent atmospheric heat transport. A part of the space that would otherwise be filled by the atmosphere is taken up by the ice sheet and also by the mountains below the ice sheet.”
Another reason is perhaps more obvious. Without ice sheets and mountains, there’s more space for the lower atmosphere to fill."
The air pressure and temperature relate in part to the gravity, and in part to the topography.
The earth is an oblate spheroid and yet the tropics which would be several kilometers higher do not have substantially lower pressure at ground level.
It implies that the height above the average ground level is more important than the actual gravitational height??
Which in turn would suggest that the ice sheet and mountain excuse is not correct??
I believe it is possible to compute a theoretical temp for every location on earth given position gravity and elevation.
It would be interesting to know if a correction has to be made in terms of local gravity and height.

Hank -

Flood myths are very common.. because the first agricultural societies arose on flood plains - for obvious reasons; they are the easiest places to practice agriculture. So years of exceptional flooding turn into myth quite readily. Most flood myths also have a bit where the floodwaters recede, which would be at odds with what happened as the glaciers melted.

By Andrew Dodds (not verified) on 23 May 2017 #permalink

The Southern Ocean has over 70,000,000 cubic km of water while the Arctic Ocean has less than 20,000,000 cubic km of water. The average depth of the Arctic is 1205 meters while the average depth of the Southern Ocean is 3270 meters. These differences - along with eight to ten times the volume of ice in the Antarctic - results in the Arctic warming up much more rapidly than the Antarctic. The source is the heat is the underwater volcanoes - this has been confirmed by numerous independent sources.

Because of this increase in heat - from the Arctic to the Antarctic - our oceans have been rapidly evaporating which results in increased cloud cover, record-breaking rainfall and raging flood waters all across the world.

Since 2014, the meltdown of the Antarctic ice has rapidly accelerated. This trend has been increasingly exponentially while billions of tons of glaciers - that extend down from the mountain tops - are pushing down on the rapidly melting, rapidly weakening ice shelves.

Antarctica is not a continent - it is mostly sea water - click here and verify with more research:…

That images shows us that almost the entire West Antarctic Ice Sheet is sitting in sea water - and the water is rapidly warming. The West Antarctic Ice Sheet and the Ross Ice Shelf are held in place by other ice and some mountains. What happens when the ice shelves collapse? The glaciers - which extend from 3,000 meters up to the mountain tops down into the warm sea water - will have nothing to keep them in place which will result in the glaciers crashing into the sea which will result in billions of tons of water being displaced which will launch colossal tsunami waves that will dislodge the other ice shelves which will result in the other glaciers crashing into the sea which will launch more colossal tsunami waves that will race all across the Earth - decimating everything. Since two of those huge chunks of ice are the size of Mexico, extending up 3,000 meters and extending down into the water another 300 meters - as the glaciers crash into the sea and launch colossal tsunami waves, the chance of survival will be next to zero.

Those who want to survive have already packed and left.

This isn't speculation - it's history repeating itself, but since very few have studied the true history of Antarctica, next to no one knows about it. The true history of Antarctica is found in the Captain's Logs - going back hundreds of years - and is corroborated by hundreds of other independent historic documents.

By Whirled Publishing (not verified) on 23 May 2017 #permalink

Thanks. I'd done something similar in between comments #5 and #6.

By ...and Then Th… (not verified) on 24 May 2017 #permalink

Captain's Log

"The source is the heat is the underwater volcanoes – this has been confirmed by numerous independent sources."

Had a good laugh this morning, while cleaning up after Spock's birthday party.

AlphaGo has defeated the world's #1, Ke Jie. "“Last year, it was still quite humanlike when it played,” Mr. Ke said after the game. “But this year, it became like a god of Go.”

NY Times article

[Yes, I watch game 1 and will now watch game 2. KJ of course has reason to vaunt AlphaGo now he has lost to it, he wasn't sounding so humble when it beat Lee Sedol -W]

By Kevin ONeill (not verified) on 24 May 2017 #permalink

WC writes: [Yes, I watch game 1 and will now watch game 2. KJ of course has reason to vaunt AlphaGo now he has lost to it, he wasn’t sounding so humble when it beat Lee Sedol -W]

The match is now concluded with AlphaGo winning 3-0.

And back in January you wrote:
"[I saw that. I think the reaction is a bit over the top. I’ve played through, quickly, two of the games and whilst the play is waay over my level, the moves all make sense – or at least, as much sense as pro games ever do. It is possible that a much better player than me like Ke might have a different perspective. Also, AlphaGo – whilst clearly very good – isn’t yet that much better than the best human; so God-like playing is beyond it just now...]"

It seems like you're just unwilling to give the AI credit.

[I don't know what you mean by that. It is clearly a very good go player, far better than me; but then, so are the pros. The moves still make sense. This time, it seemed to me that in game 2 Ke got stuffed; it looked to my eyes that he lost badly in the bottom left corner. But I haven't seen a proper game analysis, I could be wrong.

See-also -W]

By Kevin ONeill (not verified) on 27 May 2017 #permalink

>"[This time, it seemed to me that in game 2 Ke got stuffed -W]"

Seems a bit different from

" “For the first 100 moves it was the closest we’ve ever seen anyone play against the Master version of AlphaGo,” DeepMind CEO Demis Hassabis said in the post-game press conference."

Demis would have had access to AlphaGo's probability of winning info during the game is the impression I have gained. So 'Ke got stuffed' seems an odd assessment.

[Ah, but it is the only assessment that I have. Naturally, I prefer my own opinions but you are welcome to prefer someone else's -W]

I believe I heard there was a study group that believed there was a better line Ke Jie could have pursued in bottom left.

Top go players have a win ratio of less than 2.5 to 1. So alphago's 67:1 looks to be in a different league. Also a bug was found and corrected since that 1 game loss. It has also been said that since Lee Sodol match alphaGo was reworked to learn by itself only instead of starting with learning from human games. So maybe it should be viewed as 63:0. OK 60 of 63/68 games were short and not all against top pros so 63 is overdoing it a bit.

The impression being given by your comments seems to be that it has to be completely incomprehensible to be given a God like status.

[I don't know where you're getting that impression from -W]

This seems inappropriate to me. I think AlphaGo would be likely to win 98 or 99 if not 100 out of 100 3 hour each games with 9dan pros. 49:1 is a completely different win rate to human pros 2.5:1 win rate. It is enough to be considered in a different class to the top pros even if we cannot really tell if it is in a god like class.

Just found this if you are interested:…

Shi Yue, 9 Dan Professional and World Champion said the games were “Like nothing I’ve ever seen before - they’re how I imagine games from far in the future.” Gu Li, 9 Dan Professional and World Champion, said that “AlphaGo’s self play games are incredible - we can learn many things from them.” We hope that all Go players will now enjoy trying out some of the moves in the set.

[I saw those. But without commentary, they're just games by player(s) much better than me -W]