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Monday, February 10, 2014

A miscellaneous collation: fires, ice and cycles...

Sou | 8:25 AM Go to the first of 5 comments. Add a comment

There is little to report from denier bloggers this past couple of days. (In Anthony Watts' latest, he's running a competition to see who is the most offensive - "alarmists" or "fake sceptics" - archived here.)

In any case, I've been suffering what I can only describe as heat fatigue (not quite the same as heat exhaustion).  Thankfully a cool change came through yesterday afternoon.  (Last night I slept for nearly 12 hours straight.)


Bushfires rage in Australia


Firefighters who were busy battling blazes across south eastern Australia weren't so fortunate and wouldn't have got much sleep.  They were too busy fighting major fires on the outskirts of Melbourne, in the Latrobe Valley, in far east Gippsland and the southern Flinders Ranges in South Australia as well as elsewhere.  Twenty homes were thought to have been destroyed in Victoria yesterday.

It's been another hot summer down here, with more than our share of days over 40 degrees in south-eastern Australia and up north too.  The fires have been bad, but not as bad as other years.  Below is a comparison of mid-January last year with fires across Australia today:



Some of the people commenting at WUWT seem to think that the world is heading for an ice age, because it's the most snow the USA has seen in 20 years or something.  However there's no hint down under of any ice age cometh-ing.

Feel free to treat this as an open thread and comment about anything at all relating to climate.  Here are a couple of articles to get you going.


How Greenland's ice sheets are melting


First from ScienceDaily.comGreenland ice sheets are melting from above and below - more measurements are sorely needed. An excerpt:
The paper describes the mechanisms causing the melting of the ice sheet, particularly at its margin, where the glaciers extend into the ocean. This so-called "submarine melting" has increased as the ocean and atmosphere have warmed over the past two decades.
"What a lot of research around Greenland and the fjords has shown is that if the North Atlantic Ocean warms, then these warm waters will rapidly reach the fjords and hence the margins of Greenland's glaciers," says Straneo.
But scientists today know that the situation is more complex than just "a warmer ocean melts ice."
A warmer atmosphere is resulting in increased surface melting above the ice sheet, and this runoff too enhances submarine melting. Surface melt water falls through cracks in the glacier creating a freshwater river that rushes out into the ocean at the base of the glacier, sometimes 600 meters (1,800 feet) below sea level. This river mixes rapidly with the dense, salty seawater, contributing to the heat transfer from the ocean to the ice, resulting in even more submarine melting beneath the sea surface.

Accelerated trade winds over the Pacific


Matthew England from the University of New South Wales and colleagues have a paper in Nature Climate Change, which suggests that stronger than normal trade winds across the Pacific have meant that global surface temperatures haven't risen as much as they might have in recent years.  From the ABC News:
It was found the winds were churning the Pacific like a washing machine, bringing the deeper colder water to the surface and pushing the warmer water below.
"The phase we're in of accelerated trade winds particularly lasts a couple of decades," Professor England said.
"We're about 12 to 13 years in to the most accelerated part of the wind field. "It's important to point out there's a cycle we expect to reverse and when they do reverse back to their normal levels we'd expect global warming to kick in and start to rise."
Professor England rejects the argument from sceptics that the slowdown suggests global warming is not as bad as first thought and that the climate models are not working.
"We want the community to have confidence in the climate models," he said. "They are very good but in this instance the wind acceleration has been that strong and that much stronger than what the models projected."

Cycles in the South


For the cycle afficionados, David W. J. Thompson and Elizabeth A. Barnes have found periodic behaviour in large-scale Southern Hemisphere atmospheric circulation.  From the latest issue of Science (paywalled):
Periodic behavior in the climate system has important implications not only for weather prediction but also for understanding and interpreting the physical processes that drive climate variability.
Here we demonstrate that the large-scale Southern Hemisphere atmospheric circulation exhibits marked periodicity on time scales of approximately 20 to 30 days. The periodicity is tied to the Southern Hemisphere baroclinic annular mode and emerges in hemispheric-scale averages of the eddy fluxes of heat, the eddy kinetic energy, and precipitation. Observational and theoretical analyses suggest that the oscillation results from feedbacks between the extratropical baroclinicity, the wave fluxes of heat, and radiative damping.
The oscillation plays a potentially profound role in driving large-scale climate variability throughout much of the mid-latitude Southern Hemisphere.



Fiammetta Straneo, Patrick Heimbach. North Atlantic warming and the retreat of Greenland's outlet glaciers. Nature, 2013; 504 (7478): 36 DOI: 10.1038/nature12854

Matthew H England et al. Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus. Nature Climate Change, February 9, 2014; doi:10.1038/nclimate2106

David W. J. Thompson and Elizabeth A. Barnes, Periodic Variability in the Large-Scale Southern Hemisphere Atmospheric Circulation; Science 7 February 2014: Vol. 343 no. 6171 pp. 641-645 DOI: 10.1126/science.1247660

5 comments:

  1. Sou, is Antarctica ice growing in recent years?

    ReplyDelete
    Replies
    1. The (winter) sea ice around Antarctica has grown a bit, particularly this past year. There has been quite a lot written about this.

      Here is an article I wrote last year about Arctic and Antarctic sea ice. Tamino wrote an article about this just a few days ago. And here's an article in Sciencedaily.com about a paper written last year. And a more recent paper in Nature.

      On the other hand, a lot of the ice on the continent is melting. Particularly worrisome is West Antarctica and the Peninsula. Here is an article about the Pine Island glacier for example, which discusses some of the likely forces operating there. Working out just what will happen is not a straightforward exercise as that article shows.

      Delete
  2. "Some of the people commenting at WUWT seem to think that the world is heading for an ice age, because it's the most snow the USA has seen in 20 years or something. "

    Yea, well in the Four Corners area of the USA, except for a couple cold weeks in January - it been spring weather, but the calendar says it's barely February. And we would love a little snow around here!

    ReplyDelete
    Replies
    1. Same in SW Montana. A couple of cold weeks in December and last week was pretty cold, but other than that temps have been several degrees above normal for most of the winter here.

      Delete
    2. Not the same in Holland.
      Winds between SSW and SSE 90%, check, record was 79%.
      No subzero day average, check, record was, um, weeks ago?
      Days of snow zilch, 20 or so the normal.
      Nudging silver placing for warmest winters 'ever' (at least since 1706).
      So it is an unbelievably monotonous, mild season here. Most Atlantic violence stalls just to the west drenching England, though some severe gales have moved on to our country (October, December) and we might get one on Thursday.

      There was a time average duration of any circulation pattern was 3-4 days. This has doubled, but actually the statistic has gone rubbish by what is happening now. As of the second week of October there's been one pattern until second week of January, when ocean pattern remained same but a blocking high appeared over Scandinavia for two weeks - I called that 'Pattern II' and we have returned to 'Pattern I' last week with no end in sight.

      There is nothing special about the pattern. But that it remains for month after month is absolutely pathological.

      Delete

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