No warming in Antarctica. Southern Ocean Cooling Down
By Dr. Sebastian Lüning and Prof. Fritz Vahrenholt
[Translated by P Gosselin]
In Antarctica if a single piece of ice breaks off, the media worldwide go into a frenzy: How could it happen? That’s got to be climate change. Yes, global warming is striking Antarctica with full force and is rearing its ugly head. Every iceberg that breaks off at the edge of the ice sheet is a sign of climate catastrophe. Amen.
But also during pre-industrial times chunks of ice broke off regularly. This is how ice sheets work: Snow builds up on the continent and then gradually moves towards the coast. What’s new?
So just how much has Antarctica warmed over the last years and decades? One reads or hears very little about this in the media. Therefore we’d like to take this knowledge deficit as an occasion to look more carefully at the temperature history of the great white continent.
Paul Homewood once posted on the temperature development of the past 35 years, using the satellite measurements:
There’s been no detectable warming. It was cold earlier and it is cold today! No Trend.
Perhaps the thermometer at the Amundsen Scott Base at the South Pole has found warming? Based on GISS data, Paul Homewood generated the following curve:
Also in the region of the South Pole station there has been no detectable warming, and that over the past 50 years.
In the next step we leave the mainland and examine the ocean to see if it may have warmed around Antarctica. Bob Tisdale put together the temperature curve based on the KNMI Climate Explorer data:
Again we find no warming here as well. To the contrary the Southern Ocean has even cooled over the past 35 years.
In June 2014 Marshall et al. confirmed the cooling trend in a Paper in the Philosphical Transactions A. The abstract states:
In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the Southern Ocean around Antarctica has been (mainly) cooling and sea-ice extent growing.
In the paper’s main section the authors add:
Over the last few decades, the two polar regions of our planet have exhibited strikingly different behaviours, as is evident in observed decadal trends in surface air temperature shown in figure 1. The Arctic has warmed, much more than in the global average, primarily in winter, while Arctic sea-ice extent has decreased dramatically. By contrast, the eastern Antarctic and Antarctic plateau have cooled, primarily in summer, with warming over the Antarctic Peninsula and Patagonia . Moreover, sea-ice extent around Antarctica has modestly increased.
Appearing in the same year in the Annals of Glaciology was a paper by Ekaykin et al., where the temperature development of Central Antarctica was reconstructed over the past 350 years. The researchers found characteristic 30-50 years cycles. Interestingly it was warmer than today back in the 1940s than today. The following is the paper’s abstract:
Multiple climate shifts in the Southern Hemisphere over the past three centuries based on central Antarctic snow pits and core studies
Based on the results of geochemical and glaciological investigations in snow pits and shallow cores, regional stack series of air temperature in central Antarctica (in the southern part of Vostok Subglacial Lake) were obtained, covering the last 350 years. It is shown that this parameter varied quasi-periodically with a wavelength of 30–50 years. The correlation of the newly obtained record with the circulation indices of the Southern Hemisphere (SH) shows that the central Antarctic climate is mainly governed by the type of circulation in the SH: under conditions of zonal circulation, negative anomalies of temperature and precipitation rate are observed, whereas the sign of the anomalies is positive during meridional circulation. In the 1970s the sign of the relationship between many climatic parameters changed, which is likely related to the rearrangement of the climatic system of the SH. The data suggest that during the past 350 years such events have taken place at least five times. The stable water isotope content of the central Antarctic snow is governed by the summer temperature rather than the mean annual temperature, which is interpreted as the influence of ‘post-depositional’ effects.
And when we look even further back in the past, we find more surprises. During the last interglacial, the Eem Warm Period of 130,000 years ago, it was 3.5 to 4.0°C warmer than today. This was reported by Parennin et al. in a publication appearing in February 2015 in the Climate of the Past Discussions.
On this matter a paper by Conway et al. appearing in 1999 in Science is interesting. Back then the authors recognized that the West Antarctic ice sheet shrank foremost during the mid Holocene, i.e. some 5000 years ago. The scientists suspect that the melting process started already during the early Holocene some 10,000 years ago and has continued on without any external influences until today:
Past and Future Grounding-Line Retreat of the West Antarctic Ice Sheet
The history of deglaciation of the West Antarctic Ice Sheet (WAIS) gives clues about its future. Southward grounding-line migration was dated past three locations in the Ross Sea Embayment. Results indicate that most recession occurred during the middle to late Holocene in the absence of substantial sea level or climate forcing. Current grounding-line retreat may reflect ongoing ice recession that has been under way since the early Holocene. If so, the WAIS could continue to retreat even in the absence of further external forcing.
Today we would like to conclude with a curious “discovery” On May 23, 2014. Spiegel Online brought us a frightening climate alarm story:
Ice melt: Irreversible chain reaction feared in Antarctica
[…] “A large piece of the ice cap in West Antarctica finds itself at a stage or irreversible retreat,” NASA scientist Eric Rignot of the University of California, Irvine. In the previous calculations by the IPCC concerning sea level rise the phenomenon was not adequately taken into account. In a study that was recently published in the “Geophysical Research Letters” the scientists lead by Rignot studied the retreat of all six large glaciers.”
Just awful…so, who brings us this terrible news? Does Eric Rignot really know what he’s doing? Hold on to your seat: Rignot is in fact not a climate scientist. He’s an electrical engineer…just in case someone complains later on that a non-Phd does not qualify anyone to participate in the climate discussion…