Poles apart: latest Met Office sea ice report published

The latest stocktake of sea ice in the Arctic and the Antarctic has just been published by the Met Office.

It might be tempting to consider the many apparent similarities between the polar regions, but there are also key differences that can be seen in the annual cycle of the regions’ sea ice.

The year-to-year and decade-to-decade variability in the extent of sea ice can help scientists understand a lot about the impacts of both weather and climate change.

Dr Ed Blockley leads the polar team at the Met Office. He said: “Perhaps the most obvious difference is that Antarctica is a large continent ringed by ocean, whereas the Arctic is a region of ocean hemmed in by continental land masses. This difference in geography means that sea ice formation has differing influences at each end of the earth.”

The Met Office briefing on Arctic and Antarctic sea ice shows that Antarctica set a new record minimum in the southern hemisphere (austral) summer, beating the previous low in March 2017. Researchers from British Antarctic Survey looked at the factors behind the February minimum concluding that storms had the effect of displacing sea ice by pushing it away from the continent toward relatively warmer waters, leading to the record low.

You can hear an interview with Professor John Turner of British Antarctic Survey in the latest episode of our Weather Snap podcast. In mid June Antarctic sea ice extent remains very low for the time of year and on 10 June was equal lowest with 2019.

Arctic sea ice extent on 10 June in the northern hemisphere summer was the eleventh lowest on record for the time of year, following relatively slow ice loss during May. Consistent records of Arctic and Antarctic sea ice began in 1979 during the development of the satellite era.

Although the extent of sea ice shows large variation between years, in the Arctic the downward trend means the region is losing ice at an alarming rate. 

Ed Blockley added: “Arctic sea ice extent has declined in all seasons but much more so at the summer minimum in September for which we have seen a reduction of around 13% per decade. This equates to an average annual loss of September sea ice extent of more than 85,000 sq km – an area over four times the size of Wales!”

However, the trend for the Antarctic is less clear. In part this is due to the variability of weather around the Antarctic continent which has a huge influence on sea ice. Another large area of difference between the two poles is the amount of data scientists have for each pole.

Ed Blockley added: “Satellites – looking down on the ebb and flow of sea ice – provide an invaluable record, but other sets of data can provide a richer understanding of sea ice. For example, in the Arctic measurements of sea ice thickness have been taken by submarines which can travel under the ice. Much less of this sort of data is available for the Antarctic. This leaves scientists facing greater uncertainty about sea ice around the continent as we only have measurements in two dimensions and not three dimensions like we have for the Arctic.”

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