Right around this time of year, mid to late September depending on weather factors, Arctic ice reaches its annual minimum. This year, there are signs that the annual refreeze has already begun, which would leave 2016 as the second lowest ice extant in the modern record, and that’s in a year with greater than average cloud cover over critical portions of the region:
"It was a stormy, cloudy and fairly cool summer," US National Snow and Ice Data Center (NSIDC) director Mark Serreze said in a statement. "Historically such weather conditions slow down the summer ice loss, but we still got down to essentially a tie for second lowest on the satellite record."
The culprit is polar amplification. Global warming directly causes snow and ice to melt exposing darker land and sea, which absorbs more sunlight, causing more warming. The cycle feeds back more viciously in the icy, reflective cryosphere than elsewhere.
For now, the area covered by ice may have finally bottomed out at an estimated 1.6 million square kilometers a few days ago. The all time low record of 1.31 square km was set in mid September of 2012. Ice volume is a much more difficult thing to measure than simple area, but by the most careful estimates available, we may have lost over half of the overall Arctic ice volume compared to the baseline average. A straightforward extrapolation of ice volume loss over that time suggests the Arctic may be essentially or literally ice free during summer minimums sometime between 2025 and 2050.
