KMSP - On September 11, the Arctic Ocean’s sea ice dipped to its yearly low of about 1.7 million square miles, the 4th lowest in satellite record, but well above the lowest recorded year of 2012. Satellite records date back to 1979 so we still have a very small sample size, but the sea ice is on par with the last decade or so staying well below what is considered “normal”. But it is this normal that has always been up for debate because of the small sample size.
The sea ice minimum always occurs in September when spring and summer heat finally allow water temperatures to climax over the oceans before the continued dissipating daily sunshine has an effect on how warm those waters are. Remember that water always takes longer to warm and cool than air does so there will always be a lag between peak heating of air temperatures during the summer in the Northern Hemisphere and the peak heating of water temperatures.
Conversely, the Antarctic sea ice extent peaks in September. The Antarctic sea ice will be near what’s considered normal which is a far cry different from the last few years, setting record highs in 4 of the last 7.
You can see how this year compares to the last few years near the North Pole with the graph below… the light blue line indicates 2015.