The Arctic is currently experiencing hot sea surface and air temperatures, making it very difficult for sea ice to form. A record low extent of sea ice in the Arctic Ocean is expected this winter. This week, researchers reported that air temperatures in the Arctic are an astonishing 20°C (68°F) higher than normal for the time of year. Sea temperatures are averaging nearly 4°C (39°F) higher than usual. The near-record low extent of sea ice this summer has actually brought about a warmer-than-usual autumn, because large areas of open water raise air temperatures above them. Air temperatures, in turn, drive the formation of ice.

Arctic sea ice, which forms and melts each year, has declined more than 30% in the past 25 years. Currently, it has been at the lowest extent ever recorded for late November, beating even 2012, the previous lowest-level record-holder (shown in the satellite photo opposite—the yellow line shows the average extent 1979–2010). It provides yet more evidence for global warming.

Scientists warn that the ice shrinkage could trigger what they call “tipping points”, with serious consequences for other environments. When sea ice melts, it leaves behind areas of dark ocean water which absorb more heat than the ice (the ice tends to reflect the sun’s rays back into space). This in turn causes further shrinkage. A warming ocean may cause altered climate patterns across the globe, not just in the Arctic region, possibly even affecting the Asian monsoon.