Followup on Antarctic Melt Rates

I got an email today in response to this post that allows me to cover some ground I wanted to cover.  A number of commenters are citing this paragraph from Tedesco and Monaghan as evidence that I and others are somehow mischaracterizing the results of the study:

“Negative melting anomalies observed in recent years do not contradict recently published results on surface temperature trends over Antarctica [e.g., Steig et al., 2009]. The time period used for those studies extends back to the 1950’s, well beyond 1980, and the largest temperature increases are found during winter and spring rather than summer, and are generally limited to West Antarctica and the Antarctic Peninsula. Summer SAM trends have increased since the 1970s [Marshall, 2003], suppressing warming over much of Antarctica during the satellite melt record [Turner et al., 2005]. Moreover, melting and surface temperature are not necessarily linearly related because the entire surface energy balance must be considered [Liston and Winther, 2005; Torinesi et al., 2003].”

First, the point of the original post was not about somehow falsifying global warming, but about the asymmetry in press coverage to emerging data.  It is in fact staggeringly unlikely that I would use claims of increasing ice buildup in Antarctica as “proof” that anthropogenic global warming theory as outlined, say, by the fourth IPCC report, is falsified.  This is because the models in the fourth IPCC report actually predict increasing snowmass in Antarctica under global warming.

Of course, the study was not exactly increasing ice mass, but decreasing ice melting rates, which should be more correlated with temperatures.  Which brings us to the quote above.
I see a lot of studies in climate that seem to have results that falsify some portion of AGW theory but which throw in acknowledgments of the truth and beauty of catastrophic anthropogenic global warming theory in the final paragraphs that almost contradict their study results, much like natural philosophers in past centuries would put in boiler plate in their writing to protect them from the ire of the Catholic Church.   One way to interpret this statement is “I know you are not going to like these findings but I am still loyal to the Cause so please don’t revoke by AGW decoder ring.”

This particular statement by the authors is hilarious in one way.  Their stated defense is that Steig’s period was longer and thus not comparable.  The don’t outright say it, but they kind of beat around the bush at it, that the real issue is not the study length, but that most of the warming in Steig’s 50-year period was actually in the first 20 yearsThis is in fact something we skeptics have been saying since Steig was released, but was not forthrightly acknowledged in Steig.   Here is some work that has been done to deconstruct the numbers in Steig.  Don’t worry about the cases with different numbers of “PCs”, these are just sensitivities with different geographic regionalizations.  Basically, under any set of replication approaches to Steig, all the warming is in the first 2 decades.

Reconstruction

1957 to 2006 trend

1957 to 1979 trend (pre-AWS)

1980 to 2006 trend (AWS era)

Steig 3 PC

+0.14 deg C./decade

+0.17 deg C./decade

-0.06 deg C./decade

New 7 PC

+0.11 deg C./decade

+0.25 deg C./decade

-0.20 deg C./decade

New 7 PC weighted

+0.09 deg C./decade

+0.22 deg C./decade

-0.20 deg C./decade

New 7 PC wgtd imputed cells

+0.08 deg C./decade

+0.22 deg C./decade

-0.21 deg C./decade

Now, knowing this, here is Steig’s synopsis:

Assessments of Antarctic temperature change have emphasized the contrast between strong warming of the Antarctic Peninsula and slight cooling of the Antarctic continental interior in recent decades1. This pattern of temperature change has been attributed to the increased strength of the circumpolar westerlies, largely in response to changes in stratospheric ozone2. This picture, however, is substantially incomplete owing to the sparseness and short duration of the observations. Here we show that significant warming extends well beyond the Antarctic Peninsula to cover most of West Antarctica, an area of warming much larger than previously reported. West Antarctic warming exceeds 0.1 °C per decade over the past 50 years, and is strongest in winter and spring. Although this is partly offset by autumn cooling in East Antarctica, the continent-wide average near-surface temperature trend is positive. Simulations using a general circulation model reproduce the essential features of the spatial pattern and the long-term trend, and we suggest that neither can be attributed directly to increases in the strength of the westerlies. Instead, regional changes in atmospheric circulation and associated changes in sea surface temperature and sea ice are required to explain the enhanced warming in West Antarctica.

Wow – don’t see much acknowledgment that all the warming trend was before 1980.   They find the space to recognize seasonal differences but not the fact that all the warming they found was in the first 40% of their study period?   (And all of the above is not even to get into the huge flaws in the Steig methodology, which purports to deemphasize the Antarctic Peninsula but still does not)

This is where the semantic games of trying to keep the science consistent with a political position get to be a problem.  If Steig et al had just said “Antarctica warmed from 1957 to 1979 and then has cooled since,” which is what their data showed, then the authors of this new study would not have been in a quandary.  In that alternate universe, of course decreased ice melt since 1980 makes sense, because Steig said it was cooler.  But because the illusion must be maintained that Steig showed a warming trend that continues to this date, these guys must deal with the fact that their study agrees with the data in Steig, but not the public conclusions drawn from Steig.  And thus they have to jump through some semantic hoops.

  • Fred from Canuckistan . . .

    The Steig study was also very, very geographically “challenged” with a statistical weighting scheme that Climate Audit ripped into little bitty pieces of crapola.

  • AztecBill

    The book The Chilling Stars proposes that solar changes effect low level clouds that lead to climate change. More low level clouds will cool the Arctic but warm the Antarctic. So the fact that the two areas have warmed and cooled at opposite times lends credence to changes in low level clouds as the reason.

  • NormD

    Can someone explain me why raising the temperature of Antarctica from say -50 to -45 would have any effect on ice melt?

  • Brian Klappstein

    I posted some comments on the Steig story over at RealClimate.org, suggesting that 1980 might be the warmest year for some manned stations in Antarctica, and got slapped down with a response that I hadn’t done my homework and used a graph of AWS’s, and manned stations showing warmest year by station to show how wrong I was. However, after some other posters and myself noted that pretty much no AWSs existed in 1980, the response to my post was appended with this comment: “…Still, your point is not unreasonable — not all of Antarctica has warmed significantly, and in the last few decades East Antarctica’s trend has flattened. Nowhere do we claim otherwise.–eric..”

  • Norm

    North Pole summers ice-free in 10 years: researchers say
    Last Updated: Wednesday, October 14, 2009 | 8:45 PM ET

    The Associated Press

    The North Pole will turn into an open sea during summer within a decade, according to data released Wednesday by a team of explorers who trekked through the Arctic for three months.

    The Catlin Arctic Survey team, led by explorer Pen Hadow, measured the thickness of the ice as it sledged and hiked through the northern part of the Beaufort Sea earlier this year during a research project.

    Their findings show that most of the ice in the region is first-year ice that is only around 1.8 metres deep and will melt next summer. The region has traditionally contained thicker multiyear ice, which does not melt as rapidly.

    “With a larger part of the region now first-year ice, it is clearly more vulnerable,” said Professor Peter Wadhams, part of the Polar Ocean Physics Group at the University of Cambridge, which analyzed the data.

    “The area is now more likely to become open water each summer, bringing forward the potential date when the summer sea ice will be completely gone.”

    Wadhams said the Catlin Arctic Survey data supports the new consensus that the Arctic will be ice-free in summer within 20 years, and that much of the decrease will happen within 10 years.

    Martin Sommerkorn of the World Wildlife Fund said the Arctic sea holds a central position in the Earth’s climate system.

    “Such a loss of Arctic sea ice cover has recently been assessed to set in motion powerful climate feedbacks which will have an impact far beyond the Arctic itself,” he said.

    He added: “This could lead to flooding affecting one-quarter of the world’s population, substantial increases in greenhouse gas emissions from massive carbon pools and extreme global weather changes.”

    Global warming has raised the stakes in the scramble for sovereignty in the Arctic because shrinking polar ice could someday open resource development and new shipping lanes.

    The rapid melting of ice has raised speculation that the Northwest Passage linking the Atlantic and Pacific oceans could one day become a regular shipping lane.

    The results come as negotiators prepare to meet in Copenhagen in December to draft a global climate pact.

  • Francis Manns

    Martin Sommerkorn of the World Wildlife Fund said the Arctic sea holds a central position in the Earth’s climate system.

    “Such a loss of Arctic sea ice cover has recently been assessed to set in motion powerful climate feedbacks which will have an impact far beyond the Arctic itself,” he said.

    He added: “This could lead to flooding affecting one-quarter of the world’s population, substantial increases in greenhouse gas emissions from massive carbon pools and extreme global weather changes.”

    Critical thinking required: melting floating ice will not raise sea level at all. It’s already in the ocean.

  • Steve Dickey

    Why is it that when those using arctic ice reduction figures are questioned about antarctic ice increases, the argument goes something like this-“… yeah, most of the warming in the most prevalent studies happened prior to 1980, but the ARCTIC ice is receding..” Antarctic ice volume is MUCH larger that that of the northern hemisphere combined, and as such, has a balancing effect on the whole picture.
    I agree that we need to minimize our use of all materials, utilize the most efficient methods of power production, transportation and manufacturing, and in general use our planet well, but the fact we cannot predict weather for more than 3-5 days with any degree of certainty, we must take all scientific conclusions with a grain of salt.

  • hunter

    Norm,
    Those are the same researchers that said, about 4 years ago, that we ahd 4 years to prevent a climate tipping point that would kill us all.
    Those are the same researchers who said that the 2004 and 2005 hurricane seasons were caused by AGW, and that we would be seeing those types of storms yearly.
    Those are the same researchers who have been saying that AGW is much worse than predicted every few months for the past 20 years.
    Those are the same researchers who predicted the last year the Arctic would be ice free.
    And the Catlin survey is fraud. Period.

  • Wally

    Norm,
    It’s not the surface temp you have to worry about. Its the base temp. Which was about -9. Take off 1 or 2 degrees cause ice squishes quickly under that much weight, now, deduct the few degrees the global temps gone up in the last 20 years that is filtering into the system as we speak, Now we are talking about a few degrees, not -45 or -50 but -4, -5 or -6. How many coal fired power stations does it take to knock off another degree 10, no. 100 maybe, 500, now were cooking, how about 1000? We are talking about 10 to 20% of the remaining safety margin.

    Now that the constraining and insulating ring of ground ice around Antarctica is going, going, gone… add in a lot of fresh surface melt that FLOWS DOWN to refreeze (EXPAND) taking away more cold from the base and forcing the glaciers to accelerate more each year (thats accelerate not just move). Double the number of melt days each year and climbing.
    So we have twice the lateral pressure over twice the time period with twice the heat thats 2 x 2 x 2 = 8 times change over time. Then feel what happens when the first really big chunk of ice (say 100k by 1k) falls into off the land into a deep ocean, (that wave will ruin the east coast of Australia evidenced in sediments in the North Western valleys behind Newcastle NSW etc.) Such a big splash and a big shake, may trigger other actions.

    Add in the once frozen methane now bubbling up from the ocean floor……. 25 times worse than Co2 and lots of it.

    And through in another billion people all wanting a shiny new car…

    Has science proven that smoking is slow murder? Have the politicians band cigarettes? No.
    Did a thousand PhD’s in economics predict the GFC?
    How many species a day are we killing?
    It took us million years to invent the wheel and climate science receives less funding than a failed American Bank.

    We learn the hard way, it makes us tough then smart, fight and flight is one way of saying their are only 2 options. When there are hundreds.

    Are insurance companies winding down their costal portfolios? yes! (sub, sea prime)

    Can you get a housing loan with out insurance? Not usualy!

    How high is the sewerage system above sea level? The absolute minimum (its cheaper).

    How many US dollars will have to be printed to save Florida alone.

    What will it cost to move just in displaced farming land.

    And now instead of moving to higher ground someone is going to tell me that its all crap, fine they are your children, do nothing.

    Norm,
    Can someone explain me why raising the temperature of Antarctica from say -50 to -45 would have any effect on ice melt?
    October 14, 2009, 9:55 am