Showing posts with label Neven Acropolis. Show all posts
Showing posts with label Neven Acropolis. Show all posts

Monday, August 12, 2013

Cyclone raging on Thin Ice

Another cyclone is raging over the Arctic Ocean. The Naval Research Laboratory image below shows the speed and drift of the sea ice.

[ click on image to enlarge ]
Last time a cyclone hit the Arctic, this resulted in a temporary increase in area covered by sea ice, as shown on the Cryosphere Today image below. The cyclone pushed down on the sea ice, flattening it and pushing it sideways. 


Note that area as measured by the Cryosphere Today includes all spots that have a 15% or higher concentration of ice. This way of measuring area ignores the fact that the cyclone reduced the sea ice concentration in many spots, from a high sea ice concentration (around 90%) to a lower concentration (less than 80%), as shown on the Naval Research Laboratory image below. 


Furthermore, sea ice has since dropped in thickness, as illustrated by the Naval Research Laboratory image below. 

Much of the ice is now less than one meter thick, while some areas close to the North Pole have ice that is only between zero and half a meter thick.

The cyclone is raging most fiercely in those areas and much of the ice is drifting out into the Atlantic Ocean.

Neven mentioned at the Arctic Sea Ice Blog that average thickness (crudely calculated by dividing PIOMAS (PI) volume numbers with Cryosphere Today (CT) sea ice area numbers, see image below) had a very steep drop in July, similar to the drop in 2010. This year's trend line is now lowest, probably signifying that the ice pack is spread out and thin at the edges (read: melting potential).

[ click on image to enlarge ]
The image below, from the University of Bremen, Germany, shows sea ice concentration on August 11, 2013.



Wednesday, September 12, 2012

An accounting is now due

By Nathan Currier

Arctic Crisis: Far From Sight,
the Top of the World's Problems

Nathan Currier, senior climate advisor for Public Policy Virginia

As this year's sea ice extent bottoms out, it's high time that more people recognize we're in a global crisis -- the Arctic crisis. I'm sorry if this sounds “alarmist”, but the Arctic, fundamental to the stability of our weather patterns, climate and agriculture, is rapidly coming apart. In the end, of course, this will just be a sub-plot to the bigger drama, the climate crisis, but by naming this the arctic crisis, I am suggesting that it needs to be treated independently, right away. It is the heart of the near-term climate issue, and its outcome could greatly alter the outcome of the larger story, which will be the saga of the century no matter what we do.

A crisis above all means this: a compression of time. In a medical crisis, for example, we expect that there will initially be the need to regain stability through some immediate means, and then other courses of treatment will be added subsequently to address the underlying problems. If the initial steps are not taken quickly enough, the whole trajectory can be different, rendering something quite manageable more dire, potentially even fatal. Because the arctic, which has received the brunt of warming, seems poised to pass a profound state shift in the very near future (in fact it's already underway), and because it offers such vital 'services' to the planet, one could say that the urgency of the larger climate crisis is for the time being mostly contained within this arctic crisis.

But before looking at what to do, or even describing what's at stake, there's another order of business to turn to. An accounting is now due. Today I want to look back at the most authoritative recent opinions suggesting that this isn't a crisis, and see how they've been holding up. In our pre-election season of fact-checking, let's call this the 'Arctic crisis debate' fact-checking 101. But since no one else has really been referring to an Arctic crisis, what we'll be looking at are some prominent statements from 2012 concerning the two great interrelated features of arctic stability: the state of its cryosphere, and the state of its carbon stocks. In particular, the sea ice and methane.

An accounting
is now due! 

When I last wrote, it was after a flurry of methane articles, including the front page New York Times article last December on the danger of increasing arctic methane emissions, followed by David Archer's curious Much Ado about Methane piece in RealClimate, the leading climate science blog. That article put strangeness into high gear by essentially discounting the value of near-term climate altogether. But Much Ado about Methane was valuable, too, in that Archer unwittingly demonstrated, with all his authority, just how far from 'Nothing' reasonably likely arctic methane releases could be. Archer provided a graph in his follow-up showing the radiative impact of a 10Gt release, only about 20% of what leading researchers of the Eastern Siberian Shelf (ESAS) think could potentially come from that region alone in the relatively near future. [Very little methane hydrate need be involved, incidentally: imagine some seismic event there, where a little shallow hydrate, a mere .05% of the hydrate there, gets released, destabilizing just .5% of the permafrost cap along with it, which gets metabolized to methane, and all this creates increased gas migration pathways for just 1% of the free gas from below -- that's 10Gt.] Radiative forcing, the measure scientists use to describe global warming, would jump globally to about 300% of its current level of increase since industrialization, and this would begin to express itself in the climate system almost right away. Much ado, indeed: that methane wouldn't be nothing.

In my last piece, I said I would quickly follow up with another one discussing what should be done to avoid such dangers, but have since remained silent. That's for a variety of reasons, one of them being a growing involvement with a group based in the UK called the Arctic Methane Emergency Group (AMEG), focused on just this question. And almost as soon as this began, RealClimate published a piece on arctic sea ice predictions, in which AMEG -- which has projected that summer sea ice could approach an ice-free minimum just a few years from now -- seemed a primary target.

Called Arctic Sea Ice Volume: PIOMAS, Prediction and the Perils of Extrapolation, it was written by a guest, Axel Schweiger (with Ron Lindsay and Cecilia Bitz), part of the team that runs the PIOMAS sea ice model at the Polar Science Center. The 'perils' it discussed were those of AMEG's use (or misuse) of their PIOMAS model, and some of us were actually flattered that our ragtag army of citizen scientists, along with a few major climate figures willing to brave academic censure for taking positions outside the status quo, like renowned sea ice expert Peter Wadhams, were receiving cannonballs lobbed from the heart of the climate establishment.

Now, it's almost a half year later, the sea ice minimum is upon us, and the ice has been doing just what AMEG predicted. As Neven Acropolis, who runs the Sea Ice Blog, wrote last week, he's particularly at a loss for words because the 2007 record has been shattered without this summer's arctic temperatures being particularly conducive to such large ice loss, which perhaps suggests something about the extraordinary underlying nature of what is taking place.

Meanwhile, AMEG had already presented its case, both in writing and orally, before a panel of the UK Parliament, on both sea ice and methane release, back at the beginning of the year. AMEG's testimony was rebutted by Julia Slingo, Chief Scientist for the UK Met Office. Now, how has this Met Office testimony held up since?

Unlike RealClimate, the Met Office chief scientist dismissed PIOMAS modeling altogether, saying that she expected better data, fitting their Hadley Center climate models, to come in soon. That data hasn't come. Far from it. Instead, just last month, the media was filled with news pieces about how the European Space Agency's new CryoSat-2, a satellite designed to read ice volume, showed far greater volume losses than expected -- much in line with PIOMAS modeling, and supportive of AMEG's position. Near the opening of her testimony, Prof. Slingo said that the 2007 melting event was really an advecting of ice, coming from extreme weather over the arctic, and not really a melting event per se. Of course, we have just noted how that 2007 record has now been widely surpassed, without such weather (nor with losses coming primarily from advection).

And when it came to methane, and the danger of releases from the arctic seabed, the UK Met Office's chief scientist said: “I think there is a lack of clarity in thinking about how that heating at the upper level of the ocean can get down, and how rapidly it can get down into the layers of the ocean.”

The Great Arctic Cyclone of 2012 has perhaps provided her with a little more clarity. Beyond that, the Chief Scientist's statement was embarrassing: after all, even those most convinced that there is little danger of large immediate methane releases do not doubt the well established and drastic warming of the sea bottom precisely in the most methane-rich areas (see this paper), and Lena river discharge also greatly impacts the seabed in some of this same region, providing yet another mechanism for seabed warming. Prof. Slingo said: At the moment, our estimates are that the increases in sea floor temperatures that have been observed have at the most been about one-tenth of a degree, except in one or two regions, like the West Spitsbergen Current.

Clearly, Prof. Slingo doesn't seem to have studied the ESAS, where anomolies of 5ºC at the seabed have been recorded, where almost all of it has warmed some 20 times more than she says (and is still currently warming, ten times more than she suggests per decade), where significant areas of permafrost cap are thawing or already thawed, and where methane is starting to be released (see my own last post on all these points). Unlike the phony “Climategate” scandal, this is a true embarrassment for climate science. And if such “expert” testimony helps the arctic climate to pass through some invisible gate without our society lifting a finger to stop it, it will also turn out to have been one of the greatest tragedies of modern times.

So, how now, for the ice and methane? Schweiger's Perils of Extrapolation piece clearly stated how PIOMAS shows September sea ice volumes having dropped by a breathtaking 75% over just the last few decades (1979-2011). It might even seem simple to deduce that ice-free minima would be arriving quite soon, given this. But it is, I would agree, a vastly complex situation. Fully coupled models - those that do not, like PIOMAS, leave out the atmosphere, the weather, etc., but that try to create a realistic world that can be run into the future -- almost all suggest an eventual dampening effect on the underlying feedbacks leading to ice loss once it is mostly gone, thus leading to a long 'tail' of one or more decades in which a small amount of thinner summer ice remains, rather than an imminent disappearance, as both AMEG's Peter Wadhams and Wieslaw Maslowski, whose work Gore cited in his 2007 Nobel speech, have suggested.

That dampening, however, isn't happening. One almost feels sorry for Gavin Schmidt at RealClimate these days. After their latest sea ice update, he repeated in its comment thread how there is no reason to extrapolate PIOMAS into the future using an exponential curve (which shows a collapse just a few years from now). RealClimate wants to deal with the real underlying physical mechanisms involved, not just take some simple line that best fits the ice's past behavior and then extrapolate that line into the future. But, darn! The newest PIOMAS data have just been released last week, and, again, that exponential curve is being eerily followed by the real world's sea ice! In fact, Wieslaw Maslowski has also developed a new model recently, a fully coupled model free from 'perilous extrapolations,' which shows much the same thing as his prior research -- that a summer sea ice collapse is likely in the coming years, not decades.

As you can see, the reasons for thinking that there isn't an arctic crisis are about as firm as cotton candy. Next you'll need to learn the more solid reasons for suspecting that there is one. Then, after that, the big questions -- What real climate perils could this entail? What should we be doing about it right now? -- are what one needs to turn to next.

[First posted at the Huffington Post; posted with author's permission]

Sunday, June 17, 2012

Arctic sea ice area falling rapidly



Above graph, produced by Neven Acropolis of the Arctic Sea Ice Blog from Cryosphere Today data, features in the recent post at Climate Progress, entitled: Death Spiral Watch: Arctic Sea Ice Takes A Nosedive.

As Neven adds, 2012 has over half a million of square kilometres less ice than record minimum years 2007 and 2011.


In above image, from the National Snow and Ice Data Center (NSIDC), Neven compares sea ice extent in March 2012 and June 2012, illustrating how much sea ice has disappeared within the past three months.

Note the difference between sea ice extent and area, as described in te NSIDC FAQ page:
A simplified way to think of extent versus area is to imagine a slice of Swiss cheese. Extent would be a measure of the edges of the slice of cheese and all of the space inside it. Area would be the measure of where there is cheese only, not including the holes. That is why if you compare extent and area in the same time period, extent is always bigger.
For more graphs, also read Neven's post ASI 2012 update 5: when graphs agree, and my earlier post Arctic sea ice volume on track to reach zero around 2015

I like to add an image that I made some time ago: