By Paul Homewood
It is commonly known that the Antarctic Peninsula has seen substantial warming in the last few decades. Jim Steele wrote a guest post for WUWT a couple of days ago, “The Greatest Climate Myths of All”, which contained these observations about Antarctica:
As seen in NASA’s map of regional warming, the Antarctic Peninsula is another unusual “hotspot”, but relative to other climate dynamics, the contribution from CO2 is again not readily apparent. Stronger winds from the positive phase of the Antarctic Oscillation (AAO) increased regional temperatures without adding heat via 2 mechanisms.
First stronger winds from the north reduced sea ice extent by inhibiting the expansion of sea ice along the western Antarctic Peninsula and Amundsen Sea. As in the Arctic, more open water allows larger amounts of stored heat to escape, dramatically raising winter temperatures. Accordingly, during the summer when sea ice is normally absent, there is no steep warming trend.
The eastern side of the Antarctic Peninsula behaves in a contrary manner. There sea ice was not reduced and surface temperatures average 5 to 10° cooler, and the steep winter warming trend was not observed. However there was a significant summer warming trend. Previously during the negative phase of the AAO, weaker winds are typically forced to go around the mountainous peninsula. However the positive AAO generated a wind regime that moved up and over the mountains, creating anomalous foehn storms on the eastern side of the peninsula. As the winds descend, temperatures adiabatically rise 10 to 20 degrees or more due to changes in pressure without any additional heat.
I cannot comment on the science behind this, but I can show how the actual temperature records support what Jim says.
Let’s start with the western side, where we have two long running stations, the two British Antarctic Research stations of Rothera and Faraday.
Rothera 67.34S 68.08W
Faraday 65.15S 64.16W
First, winter temperatures, using GISS data. There is a clear and sizeable upward trend.
And now summer. The trend at Rothera is slightly down, and at Faraday slightly up. (Note, though, the differences in scale to the winter graphs – at Faraday, for instance, we are only looking at a trend of less than half a degree in summer.)
Crossing to the other side of the Peninsula, we find the station of do Marambio on the eastern side.
do Marambio 64.24S 56.62W
In stark contrast to Rothera and Faraday, winter temperatures at the Argentine station of do Marambio are actually declining.
Whilst in summer temperatures are increasing.
The numbers certainly support Jim Steele’s arguments, and suggest that it is regional factors that have led to recent warming there.
Sources
Temperature data is from SCAR datasets (Scientific Committee on Antarctic Research), available via GISS.
http://data.giss.nasa.gov/gistemp/station_data/
Pfft. We can homogenize that cooling trend away for you.
Thank you.
But, if you look at Morambio, temperatures have been decreasing greatly during the last 12 years consistent with the pause in global warming.
So you don’t have enough stations to make a valid submission for a whole continent. ICE extent is increasing?
Morambio temperatures have been decreasing since 1995.
I see more rising trends than declining trends, and more steeply rising trends than declining, so the point is…. ??
@ur momisugly Paul Homewood
It would be helpful to also see the yearly temps at each location too.
Barry
I see more rising trends than declining trends, and more steeply rising trends than declining, so the point is…. ??
Did you read Jim Steele’s post?
When you talk winter temperatures that go back to 50’s, 60’s, and 70’s…were they “colder” because of the COLD WAR? Who maintained the sites???
On today’s sea ice page, the NSIDC satellite mosaic picture shows a large calving event from sea ice adjacent to the Avery ice shelf, but no news info has been forthcoming. Of note, that satellite mosaic process sometimes displays artifacts of the microwave measurement interpretations used to produce the image, but those artifacts usually just appear as dots on the ocean.
http://nsidc.org/data/seaice_index/images/daily_images/S_bm_extent_hires.png
A slightly longer perspective from Gomez Dome ice core, just below the base on the penisula:
http://climategrog.wordpress.com/?attachment_id=53
I hope Paul has saved a secure copy of that gistemp data. Having pointed out the 12 yrs drop since ’02 (Thanks, BenS) I’d anticipate a hard drive crash at GISS a la IRS/EPA……ooops, where’d that data go….. Or at least some HEAVY homogenization…..
Thanks , Paul . Could you indicate the AAO on the timescales of those graphs ?
Not too surprising – when ice accumulates, less ocean heat accessible.
When sea ice receeds, more ocean heat available.
Jim Steele: “As the winds descend, temperatures adiabatically rise 10 to 20 degrees or more due to changes in pressure without any additional heat.”
This is nonsense.
Temperature is a measure of heat energy. It does not matter how something gets hotter, but if it gets hotter it contains more heat.
In the case of lapse rate it is basically gravitational potential energy that is being converted into heat, but heat it is.
Do the thermometers at each station represent the surrounding temps or are they located in sheltered “microsites” ??
The nearby Ross Ice shelf station shows a radically different annual profile.
http://data.giss.nasa.gov/cgi-bin/gistemp/show_station.cgi?id=700892620009&dt=1&ds=14
What are the SSTs on the west and east sides of the peninsula??
Maybe the Antarctic peninsula temps do no represent global temps??
East Antarctica has four temperature stations since the IGY. Amundsen-Scott, Vostok, Halley and Davis. Annual temp records for all four stations show zero warming since 1958. Maybe Antarctica is immune from CO2 induced warming.
Thanks Paul
I no longer trust GISS at all
…..using GISS data
How can anyone discuss temperature variations on the Antartic Peminsula without consideration of the active volcanic activity?
It’s also interesting to think what goes up must come down. The same air went up before coming down and so must have cooled adiabatically by 10-20 degrees. That in itself does not explain it being warmer than surrounding low level air.
Thanks Paul, I greatly appreciate the follow up details.
It would be interesting to see how long each of these weather stations have been operating, and to see their raw data. This might give a more accurate overall temperature trend for the whole of antarctica:
http://amrc.ssec.wisc.edu/aws/images/2010_AWS_Sites_ALL_04_12_2011-Final.jpg
“First stronger winds from the north reduced sea ice extent by inhibiting the expansion of sea ice along the western Antarctic Peninsula and Amundsen Sea. ”
This is highly dubious as well. Extent is just a measure of how spread out the bits of ice are. Compact or not does not change the surface of exposed ocean.
A change in ice area could conceivably change the degree of stabilising effect oceans have nearby land temperatures but this argument about winds compacting the sea ice is spurious.
Greg Goodman said, “Temperature is a measure of heat energy.” True, but it does not measure the quantity of heat. A review of Boyle’s Law should help clear that up.
i have watched Antarctic sea ice for years. Three years ago for the first time in all the time I have observed, the peninsula it was surrounded by sea ice.Last year it happened again. This year it has come very close to being surrounded. By going to null earth you can see that the ebb and flow of sea ice is a direct result of wind speed,direction and sea surface temp. .
Greg Goodman says: “This is nonsense”
Greg you obviously are caught grossly unaware. Foehn storms and their physics are well documented around the world. I am not sure why you deny well-known science. Compressing air will heat it. PV=nRT. Backpacking I used a fire starter that simply compressed air to ignite tissue. It was commonly used by natives from Burma to the Philippines. Changes in latent heat add to the effect. As the air goes up moisture condenses and releases latent heat that did not raise temperatures not on the windward side.
On the eastern side of the peninsula where sea ice is trapped against the shore, the cold inversion is maintained as katabaitc winds descend across the Weddell Sea. Temperatures are always 5 to 10 degrees colder on the eastern side despite being at the same latitued. In contrast the western side always has more open water and ventilating heat not only warms but disrupts the cold inversion layer and supplies moisture to the winds. When the winds shift to an up and over regime, anomalous foehn storms erupt. Most observers report the melt ponds on the Larsen Ice shelf just before its collapse were the result of the observed foehn storm.
But moisture is not always needed. In “Foehn Winds in the McMurdo Dry Valleys, Antarctica: The Origin of Extreme Warming Events” Speirs et al (2012) write “Foehn-induced warming frequently exceeds 40C within several hours at valley surfaces in the MDVs during winter” and “Episodes of strong and warm westerly airflow in the MDVs have generally been attributed to adiabatic warming of descending air, however, the disagreement lies with the exact forcing mechanisms.”
Or read 321. Orr, A., et al., (2008), Characteristics of summer airflow over the Antarctic Peninsula in response to recent strengthening of westerly circumpolar winds, J. Atmos. Sci., 65, 1396–1413.
“It has been proposed that the strengthening westerlies have resulted in increased vertical deflection of relatively warm maritime air over the northern peninsula, contributing significantly to the observed warming and the recent collapse of northern sections of the Larsen Ice Shelf. In this study, laboratory and numerical modeling of airflow incident to the peninsula are employed to further understand this mechanism. It is shown that the effect of the strengthening westerlies
has led to a distinct transition from a “blocked” regime to a “flow-over” regime, that is, confirmation of the proposed warming mechanism. The blocked regime is dominated by flow stagnation upstream (i.e., little vertical deflection) and consequent lateral deflection of flow along the western side of the peninsula. The flow-over regime is dominated by vertical deflection of mid/upper-level air over the peninsula, with strong downslope winds following closely to the leeward slope transporting this air (which warms adiabatically as it descends) to the near-surface of the northeast peninsula.”