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The Antarctic In The LIA

August 7, 2013
tags: ,

By Paul Homewood

 

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Antarctic sea ice has been steadily growing in the last few years, a fact which some have attempted to blame on a warmer climate. It is worthwhile, therefore, to reflect on what the Antarctic was like during the LIA.

HH Lamb, in his “Climate: Present, Past & Future”, tells us” the greatest extent of ice on the Antarctic Ocean may have been as late as around 1900. “ While Brian Fagan, in “The Little Ice Age” states that in the 1870’s “Antarctic ice extended much further north than in Captain Cook’s time a century earlier.”… “Sailing ships traversing the Roaring Forties from Australia to Cape Horn regularly sighted enormous tabular icebergs, with some seen as far north as the mouth of the River Plate, just 350 south latitude.”

These statements are supported by many scientific studies, for instance:-

 

1) The Little Ice Age on James Ross Island – Carrivick et al

These moraines are most likely to date from a Neoglacial readvance 700-1000 years ago, broadly synchronous with the early stages of a Little Ice Age, which has been postulated but undated for James Ross Island[20] and from around the Antarctic Peninsula[21, 22].

 

2) Little Ice Age climate and oceanic conditions of the Ross Sea, Antarctica from a coastal ice core record – Rhodes et al

Increasing paleoclimatic evidence suggests that the Little Ice Age (LIA) was a global climate change event.

We use a new glaciochemical record of a coastal ice core from Mt. Erebus Saddle, Antarctica, to reconstruct atmospheric and oceanic conditions in the Ross Sea sector of Antarctica over the past five centuries. The LIA is identified in stable isotope (δD) and lithophile element records, which respectively demonstrate that the region experienced 1.6 ± 1.4 °C cooler average temperatures prior to 1850 AD than during the last 150 yr . These events are associated with three 12–30 yr intervals of cooler temperatures at ca. 1690 AD, 1770 AD and 1840 AD.  We propose that cooler Antarctic temperatures promoted stronger katabatic winds across the Ross Ice Shelf, resulting in an enlarged Ross Sea polynya during the LIA.

  

3) Cold conditions in Antarctica during the Little Ice Age – Bertler et al

It has been argued that the Little Ice Age was the most recent of the “Dansgaard Oeschger” abrupt changes in climate that occurred during the ice age. According to the classical “see-saw” hypothesis, Antarctica should have been warm during the Little Ice Age. Our ice core data show that climate conditions in Antarctica during the Little Ice Age were colder, stormier and drier, sea surface temperatures were colder and sea ice more extensive compared to now.

 

4) Little Ice Age cold interval in West Antarctica – Orsi et al

 The largest climate anomaly of the last 1000 years in the Northern Hemisphere was the Little Ice Age (LIA) from 1400–1850 C.E., but little is known about the signature of this event in the Southern Hemisphere, especially in Antarctica. We present temperature data from a 300 m borehole at the West Antarctic Ice Sheet (WAIS) Divide. Results show that WAIS Divide was colder than the last 1000-year average from 1300 to 1800 C.E. The temperature in the time period 1400–1800 C.E. was on average 0.52 ± 0.28°C colder than the last 100-year average. This amplitude is about half of that seen at Greenland Summit (GRIP). This result is consistent with the idea that the LIA was a global event, probably caused by a change in solar and volcanic forcing, and was not simply a seesaw-type redistribution of heat between the hemispheres as would be predicted by some ocean-circulation hypotheses. The difference in the magnitude of the LIA between Greenland and West Antarctica suggests that the feedbacks amplifying the radiative forcing may not operate in the same way in both regions.

 

 

So what can we conclude?

  • The LIA was much colder than now, probably peaking in the late 19thC.
  • The Antarctic was also warmer during the MWP.
  • Sea Ice was much more extensive during the LIA.
  • When it gets colder, you get more ice.
One Comment
  1. May 30, 2014 2:34 pm

    Reblogged this on the WeatherAction Blog.

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