Antarctic Trends

Data from UAH Version 6.0 show the South Polar region to be unique in that it has a Pause, if not very mild cooling, for the whole of the satellite record, since December 1978. In this post I dig in a little deeper, and also look at surface data from Australia’s Antarctic bases.

Fig.1: Monthly TLT for the South Polar region (60- 85 S)

SP monthly

Fig. 2: Three Monthly TLT

SP 3m

Both plots show no evidence of any warming. However, Land areas are warming:

Fig. 3: SP Land: 3 month means

SP land 3m

While the Ocean area is cooling:

Fig. 4: SP Oceans: 3 month means

SP ocean 3m

Summers are warming:

Fig. 5: South Polar Summers (Yearly)

SP summer

While winters are cooling rapidly:

Fig. 6: South Polar Winters

SP winter

Especially Ocean winters, when the sea ice is at its greatest and thickest extent.

Fig.7:  SP Ocean Winters

SP ocean winter

Perhaps the sea ice insulates the atmosphere from the water below the ice? If so, in summer, with sea ice extent much reduced, the atmosphere above the ocean should be warmed much more than above the land, which is almost totally covered by ice. Let’s check:

Fig.8:  SP Ocean Summers

SP summer ocean

Fig.9:  SP Land Summers

SP summer land

Nope- TLT above land area is warming at four times the rate of ocean areas.

It’s not a great mystery. Here’s why.

We should not read too much into whether individual months create records or not, nor should we stress about the seasonal differences. Here’s an example of individual Octobers.

Fig.10: Octobers from 1979-2015

SP land october

Note the rising and falling pattern: a series of below average Octobers is followed by a series of above average Octobers.  A trend using only Octobers would show warming, as the record starts with below average Octobers and ends with above average. (Just like some global datasets!)

These patterns are evident, but with different values, in all months, which is why winters appear to be cooling and summers appear to be warming.

Fig.11:  SP Ocean Junes from 1979-2015

SP ocean junes

The most we can say is that the long term trend of ALL months shows no evidence of any warming, i.e. a Pause.

So is this just an artefact of the fairly short satellite record? We can check against surface data from Australia’s Antarctic stations at Mawson and Davis. (There is insufficient overlap to make a useful splice between closed and open sites at Casey.) These stations are on the coast far from the Antarctic Peninsula.

Fig. 12:  Monthly mean temperatures, Mawson Base

mawson mean

There is a Pause, or slight cooling, over the past 62 years.

Fig. 13: Monthly mean temperatures, Davis Base

davis mean

At Davis, a Pause, or slight warming, over the past 47 years.

The Pause in the South Polar region is real.

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19 Responses to “Antarctic Trends”

  1. Geoff Sherrington Says:

    Readers might also be interested in this paper by Holger Schmithüsen et al, which postulates that more CO2 in Antarctic skies will cause cooling. This is because the air here (and nowhere else) is warmer than the ground, so IR transmission to space occurs higher up than in the general case.
    http://onlinelibrary.wiley.com/doi/10.1002/2015GL066749/full

  2. Geoff Sherrington Says:

    In July 2009 the Head of Climate at BOM, Dr David Jones, emailed this to me –
    “Macquarie Islands data shows strong warming – about 0.5C in the last 50 years. It also shows an unusal pattern of increasing rainfall and decreasing cloudiness, which is entirely consistent with climate change projections.”

    • kenskingdom Says:

      Since 1948 Macquarie Island is indeed warming- Tmin at +0.72/100 yrs, Tmax +0.84, including very strong warming in the 1970s. Since December 1978 the trend has been firmly negative: -0.48C/100 yrs. Southern Ocean influemce? I didn’t include Macquarie is because it’s not on the Antarctic mainland, and at 54 south, well outside the south polar region.

  3. el gordo Says:

    I quiz you on this over at Jo’s blog, the Subtropical Ridge appears to be stuck in the Bight all year round.

    Could this be a possible cause of the increasing sea ice extent in the Southern Ocean?

  4. MikeR Says:

    Ken/ Yet again an interesting divergence between the UAH satellite data and ground stations.

    In comparison Berkeley Earth for Antarctica ( see http://berkeleyearth.lbl.gov/regions/antarctica) gives the following trends. Since 1960 a trend of 1.05 C/century ( plus or minus 0.76C) and 2.3 C/Century (plus or minus 1.2C) since 1990.

    This is for the 53 current ground stations and 89 former stations within the Antarctic region.

  5. el gordo Says:

    SAM is in positive territory.

    https://climatedataguide.ucar.edu/climate-data/marshall-southern-annular-mode-sam-index-station-based

  6. AndyG55 Says:

    Ken , you should also include the UAH So Ex Tropicals.

  7. AndyG55 Says:

    Here is RSS south 60-70 since 1979.. Slight cooling

  8. AndyG55 Says:

    Ken, I am trying to look at summer, (DJF) and winter, (JJA) trends down south using UAH SoPol and RSS South 60-70.

    Trouble is, they seem to go different ways. Puzzled.😦

    • kenskingdom Says:

      See figures 5-11 above with my explanation for UAH. I haven’t looked at RSS but I imagine something similar applies. Although why the months should have different values I don’t know.

      • AndyG55 Says:

        Cool, I have basically the same numbers as you have for UAH summer and winter SoPol.🙂

        I’ll recheck RSS at some stage., see if I goofed.

  9. Drei Jahre Super-La Niña mit globaler Abkühlung? – ENSO-Update April 2016 – – wobleibtdieglobaleerwaermung Says:

    […] Antarctic Trends […]

  10. ngard2016 Says:

    Steve McIntyre goes after Gavin Schmidt’s ( NASA Giss)trickery. This should be very interesting.

    https://climateaudit.org/2016/04/19/gavin-schmidt-and-reference-period-trickery/#more-21871

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