The predicament and subsequent rescue of 52 passengers – both tourists and scientists – on the Russian ship Academik Shokalskiy has gripped media around the world. The smooth rescue was impressive and a great relief, although the vessel itself and its crew are still stuck – and now one of the icebreakers sent to help in the rescue, the Chinese ship Xue Long, is itself stuck in the ice.
Some commentators have remarked on what they describe as the 'irony' of researchers studying the impact of a warming planet themselves being impeded by heavy ice. With some even suggesting that the situation is itself evidence that global warming is exaggerated.
In fact, the local weather patterns that brought about the rapid build up of ice that trapped the Academik Shokalskiy tell us very little about global warming. This is weather, not climate.
Regionally, climate change can vary markedly across the Earth so to detect human influences on the climate system climate scientists must consider the Earth as a whole.
What is clear is that the impact of climate change on ice at both poles is complex.
In the area where the Akademik Shokalskiy is trapped there has been an increase in sea ice extent for the year as a whole since the late 1970s, although not for the month of December (see attached graph). The amount of ice in the area can vary considerably from year to year making ship operations difficult. The December ice extent in 2011 and 2012 was much larger than the long-term mean, and the ice in 2013 has obviously been of comparable magnitude.
We have relatively short records of the extent of sea ice across the polar regions and can only accurately examine trends since sophisticated microwave instruments became available on the polar orbiting satellites in the late 1970s. However, the records do show that since that time the two polar regions have experienced very different trends in ice extent. Arctic sea ice has been declining in extent in every month of the year, but with the maximum loss of almost 14% per decade being found in September. In contrast, sea ice extent around the Antarctic has increased in every month of the year with the largest increase being almost 4% per decade in March. The contrasting nature of the changes was highlighted in September 2012 when both polar regions experienced new record extents of sea ice for the satellite era. On 16 September the Arctic sea ice extent reached a new minimum level of 3.41m sq km, beating the previous record minimum that occurred in 2007. However, in the Antarctic there was a new record maximum extent of 19.72m sq km on 24 September, exceeding the previous record of 19.59m sq km, which occurred on 24 September 2006. In September 2013 there was even more sea ice across the Southern Ocean, beating the 2012 record.