On 16 September 2021, Arctic sea ice reached its annual minimum extent, signifying the end of the summer melting period. According to the National Snow and Ice Data centre (NSIDC), Arctic sea ice extent stood at 4.72 million square kilometres on 16 September, which is the 12th lowest September minimum on record since satellite observations began in 1979.
The extent of Arctic sea ice has on average been declining over the last thirty years, reaching its annual minimum every year in September. Whilst this year is higher than the record low sea ice extent of 3.41 million square kilometres reached in 2012, it is still around 25% lower than the long-term (1981-2010) average of 6.33 million square kilometres.
Arctic summer sea ice extent is naturally influenced by changing weather patterns, such as temperature, cloud cover, summer storms and wind patterns. Whilst this can cause fluctuations in sea ice extent from year to year, when comparing recent satellite observational records there is a clear and significant downward trend.
Manager of the Met Office Polar Climate Group, Ed Blockley, said:“Although this year’s minimum sea ice extent is not record-breaking, it is yet another year that sea ice extent has continued to follow the prevailing long-term trend of decline. We have seen a sustained long-term decline in Arctic sea ice cover over the last 4 decades, which is most pronounced at the summer minimum in September. Although there are year-to-year variations associated with the weather in individual years, we have lost, on average, around 87,000 square km of September sea ice extent each year, an area more than 4 times the size of Wales!
“Sea ice is a significant part of our climate system, and it can be heavily impacted by even minor changes in temperature. We can see these changes in the annual cycle of sea ice melt and growth, where ice is starting to melt earlier in the spring and freeze-up later in the autumn.“As global temperatures continue to increase, the Arctic is likely to heat up faster than the planet due to polar amplification. So it is really important to pay close attention to these broader trends that tell us our climate is changing.”
You can find out more about Arctic sea ice and look out for our upcoming Arctic and Antarctic end of season report here.