Posts Tagged ‘Measurement of sea ice’

Antarctic sea ice is increasing and rate of increase is accelerating

August 4, 2011

An instance of actual measurements over the last 30 years rather than just model results. Overall, sea ice extent is increasing in the Antarctic, contrary to climate model predictions for the 21st century, and this increase is accelerating and has strong regional and seasonal signatures.

A new paper in Climate Dynamics, DOI: 10.1007/s00382-011-1143-9 

(H/T The Hockey Schtick)

Sea Ice Trends in the Antarctic and Their Relationship to Surface Air Temperature during 1979 to 2009 by Qi Shu, Fangli Qiao, Zhenya Song and Chunzai Wang

Sea ice trends in the Antarctic and their relationship to surface air temperature during 1979–2009


Surface air temperature (SAT) from four reanalysis/analysis datasets are analyzed and compared with the observed SAT from 11 stations in the Antarctic. It is found that the SAT variation from Goddard Institute for Space Studies (GISS) is the best to represent the observed SAT. Then we use the sea ice concentration (SIC) data from satellite measurements, the SAT data from the GISS dataset and station observations to examine the trends and variations of sea ice and SAT in the Antarctic during 1979–2009. The Antarctic sea ice extent (SIE) shows an increased trend during 1979–2009, with a trend rate of 1.36 ± 0.43% per decade. Ensemble empirical mode decomposition analysis shows that the rate of the increased trend has been accelerating in the past decade. Antarctic SIE trend depends on the season, with the maximum increase occurring in autumn. If the relationship between SIC and GISS SAT trends is examined regionally, Antarctic SIC trends agree well with the local SAT trends in the most Antarctic regions. That is, Antarctic SIC and SAT show an inverse relationship: a cooling (warming) SAT trend is associated with an upward (downward) SIC trend. It is also concluded that the relationship between sea ice and SAT trends in the Antarctic should be examined regionally rather than integrally.

As put by Skeptical Science – “The most common misconception regarding Antarctic sea ice is that sea ice is increasing because it’s cooling around Antarctica. The reality is the Southern Ocean surrounding Antarctica has shown strong warming over the same period that sea ice has been increasing. Globally from 1955 to 1995, oceans have been warming at 0.1°C per decade. In contrast, the Southern Ocean (specifically the region where Antarctic sea ice forms) has been warming at 0.17°C per decade. Not only is the Southern Ocean warming, it’s warming faster than the global trend. This warming trend is apparent in satellite measurements of temperature trends over Antarctica”.

Antarctic Climate and Sea Ice Variability – a Brief Review by Marilyn Raphael, UCLA Geography, WRCP Workshop on Seasonal to MultiDecadal Predictability of Polar Climate, October 2010


Antarctica’s remoteness, the difficulty of conducting research there and the paucity of observations, are some reasons why the Antarctic climate and sea ice variability are not as well understood as in the Arctic. However, research has shown that the climate of Antarctica including its sea ice is dictated by numerous influences with origins ranging from the Tropics to local atmosphere/surface interactions. Over the period of record indications are that much of Antarctica is warming, led by the Antarctic Peninsula. Regional changes in atmospheric circulation, sea surface temperatures and sea ice may explain this warming. Overall, sea ice extent is increasing, contrary to climate model predictions for the 21st century, and this increase has strong regional and seasonal signatures. Sea ice variability is strongly influenced by ENSO, Southern Hemisphere Annular Mode (SAM) and by zonal wave three (ZW3) among other large scale atmospheric circulation mechanisms. The Antarctic climate and sea ice variability are reviewed with respect to the atmospheric and oceanic mechanisms that influence them.



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