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Arctic sea ice discussions

Filed under: — group @ 20 July 2011

This is a thread to discuss issues related to the 2011 Arctic sea ice minimum. The following graphs will update every day:

JAXA Sea ice extent:



Cryosphere Today sea ice concentration:



How Soon is now?

Filed under: — gavin @ 7 July 2011

Willie Soon is a name that pops up every so often in climate ‘debate’. He was the lead author on the Soon and Baliunas (2003) paper (the only paper that has ever led to the resignation of 6 editors in protest at the failure of peer-review that led to its publication). He was a recent speaker (from 37.20) at the 2011 Heartland Institute conference, and can be counted on to produce a contrarian take on any particular issue that anyone might care about – ranging from climate, to mercury in fish and polar bear population dynamics.
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Lu: from ‘interesting but incorrect’ to just wrong

Filed under: — gavin @ 5 July 2011

Some readers might recall a story from a couple of years of ago relating polar ozone depletion to cosmic rays and the subsequent failure of predictions made using that theory. The idea came from from a Qian-B. Lu (U. Waterloo), and initially seemed interesting (at least to those of us who were not specialists). Perhaps cosmic ray induced chemistry was playing some part in releasing chlorine from CFCs as well as the more accepted idea of heterogeneous chemistry on polar stratospheric particles? Lu’s predictions for increased polar ozone loss in 2008/2009 as a function of the low solar activity (and therefore higher CR flux) did not come to pass. Worse (for this idea), new analyses demonstrated that the hypothesized CR-induced CFC loss wasn’t detectable at all.
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Under and over the ice

Filed under: — gavin @ 10 March 2011

I really like the fact that there is still so much to discover about important parts of the climate system. The Bell et al paper in Science Express this week (final version in Science) reporting on the surprising results from airborne ground-penetrating radar studies of the Antarctic Ice Sheet is a great example. The ice sheets themselves are the biggest challenge for climate modelling since we don’t have direct evidence of the many of the key processes that occur at the ice sheet base (for obvious reasons), nor even of what the topography or conditions are at the base itself. And of course, the future fate of the ice sheets and how they will dynamically respond to climate warming is hugely important for projections of sea level rise and polar hydrology. The fact that ice sheets will respond to warming is not in doubt (note the 4-6 m sea level rise during the last interglacial), but the speed at which that might happen is highly uncertain, though the other story this week shows it is ongoing.

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West Antarctica: still warming

The temperature reconstruction of O’Donnell et al. (2010) confirms that West Antarctica is warming — but underestimates the rate

Eric Steig

At the end of my post last month on the history of Antarctic science I noted that I had an initial, generally favorable opinion of the paper by O’Donnell et al. in the Journal of Climate. O’Donnell et al. is the peer-reviewed outcome of a series of blog posts started two years ago, mostly aimed at criticizing the 2009 paper in Nature, of which I was the lead author. As one would expect of a peer-reviewed paper, those obviously unsupportable claims found in the original blog posts are absent, and in my view O’Donnell et al. is a perfectly acceptable addition to the literature. O’Donnell et al. suggest several improvements to the methodology we used, most of which I agree with in principle. Unfortunately, their actual implementation by O’Donnell et al. leaves something to be desired, and yield a result that is in disagreement with independent evidence for the magnitude of warming, at least in West Antarctica.

In this post, I’ll summarize the key methodological changes suggested by O’Donnell et al., discuss how their results compare with our results, and the implications for our understanding of recent Antarctic climate change. I’ll then try to make sense of how O’Donnell et al. have apparently wound up with an erroneous result.
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Cold winter in a world of warming?

Filed under: — rasmus @ 14 December 2010

Last June, during the International Polar Year conference, James Overland suggested that there are more cold and snowy winters to come. He argued that the exceptionally cold snowy 2009-2010 winter in Europe had a connection with the loss of sea-ice in the Arctic. The cold winters were associated with a persistent ‘blocking event’, bringing in cold air over Europe from the north and the east.

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A brief history of knowledge about Antarctic temperatures

Filed under: — eric @ 9 December 2010

Sources in italics.

Early 20th Century:

Scott: It’s cold here.
The media: Scott is a hero!
Scott: It’s really really cold here.
The media: Scott is a hero!
Amundsen: It’s not that cold.
The media: Scott is a hero. Oh, and Amundsen.
Public: Shackleton is a hero, but please shut up, there’s a war on.

Mid 20th Century:

Geophizzicists: Let’s find out just how cold it is.
Media: Scott is a hero!
Public: yawn…

Late 20th Century:

Scientists: It’s colder in some place than others.
Media: Antarctica is cooling.
Scientists: It’s cooling at the South Pole, but warming very fast on the Peninsula.
Media: Antarctica is cooling, but warming faster than anywhere else on earth.
Public: Huh…?

2000
Thompson and Solomon: Most of Antarctica is cooling in summer, but it is warming on the Peninsula. We think it has to do with the ozone hole.
Media: Because of ozone, Antarctica is warming faster than anywhere else on earth and we are all going to die.
Public: Huh…?

Early 21st Century:

2006
Scientists: The troposphere over Antarctica is warming significantly in winter.
Media: Even though that paper was published in Science, our readers don’t know what the troposphere is. Neither do we. Next?

2007
Scientists: The troposphere over Antarctica is warming significantly in winter and spring, especially over West Antarctica.
Media: That paper wasn’t published in Nature, so we’re not very interested.

2009
Scientists: Antarctica is cooling in fall — not summer — in some places, but warming, especially in winter and spring, especially in West Antarctica.
Media: Antarctica stops cooling! Conservative or liberal, we are ALL going to die.
Steve McIntyre: The “team” made up the data again. I don’t know what Antarctica is doing, but I think it is probably cooling.
Media: Antarctica starts cooling again, global warming is a fraud.

2010
Ryan O’Donnell: Our paper in the Journal of Climate shows a somewhat better way to look at the same data. Antarctica is warming a bit more in summer, and a bit less in winter in the Ross Sea region. In fall it is cooling a bit more too, and so the overall trends are smaller. Still, West Antarctica is definitely warming significantly, as Steig et al. found. That’s interesting.
Eric Steig: Nice paper Ryan. Thanks for sending along a pre-print.
Steve McIntyre: Hey, we got published in the Journal of Climate! Another paper showing that the “team” made up the data again! (Sotto voce): Ryan says it it is warming a bit more in summer, and a bit less in winter in the Ross Sea region. In fall it is cooling a bit more. Otherwise we get the same results, though the magnitude of the trends is smaller. But West Antarctica is still warming significantly. But I really don’t care. The peer review process is broken, which is why.. umm…our paper was published in the leading climate journal.
Liberal Media: That paper wasn’t published in Nature, so we’re not very interested.
Conservative Media: Antarctica is cooling. Global warming is a fraud.
Public: zzzZZZzzz
————-
P.S. For those actually interested, yes, I’ll have more to say about O’Donnell et al., but overall, I like it.–eric

The A-train

A little behind schedule, I finally found time to read the article in the July 2010 edition of Physics TodayTouring the atmosphere aboard the A-Train” by Tristan S. L’Ecuyer and Jonathan H. Jiang. I think this article is a worth-while read, telling a fascinating story about how new satellite missions lead to greater understanding of our climate system.

PhysicsYoday, July 2010, Figure 1

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An icy retreat

Filed under: — group @ 26 July 2010 - (Deutsch) (Español)

Guest Commentary by Dirk Notz, MPI Hamburg

It’s almost routine by now: Every summer, many of those interested in climate change check again and again the latest data on sea-ice evolution in the Arctic. Such data are for example available on a daily basis from the US National Snow and Ice Data Center. And again and again in early summer the question arises whether the most recent trend in sea-ice extent might lead to a new record minimum, with a sea-ice cover that will be smaller than that in the record summer of 2007.

However, before looking at the possible future evolution of Arctic sea ice in more detail, it might be a good idea to briefly re-capitulate some events of the previous winter, because some of those are quite relevant for the current state of the sea-ice cover. The winter 2009/2010 will be remembered by many people in Europe (and not only there) as particularly cold, with lots of snow and ice. Not least because of the sustained cold, some began to wonder if global warming indeed was real.

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Is Pine Island Glacier the Weak Underbelly of the West Antarctic Ice Sheet?

Filed under: — eric @ 9 November 2009

Guest post by Mauri Pelto

AntarcMapPeltoIt is popularly understood that glaciologists consider West Antarctica the biggest source of uncertainty in sea level projections. The base of the 3000-m thick West Antarctic Ice Sheet (WAIS) – unlike the much larger East Antarctic Ice Sheet – lies below sea level, and it has been recognized for a long time that this means it has the potential to change very rapidly. Most of the grounded West Antarctic ice sheet drains into the floating Ross and Ronne-Filchner ice shelves, but a significant fraction also drains into the much smaller Pine Island Glacier. Glaciologists are paying very close attention to Pine Island Glacier (“PIG” on map, right) and nearby Thwaites Glacier. In the following guest post, Mauri Pelto explains why.
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