Wednesday, 19 October 2016

Record low Arctic ice again

Arctic Sea Ice Falls into Record Low Ranges — Again

Extreme Arctic warmth this fall has again pushed sea ice levels into record low ranges.
18 October, 2016

Across the Arctic, temperatures for the months of September and October have ranged between 3 and 5 degrees Celsius above normal for the entire region above the 66 degree north latitude line. Such extremely high temperatures have served to slow the rate of sea ice accumulation. The result is that the line in the sea ice graphs appears to be moving more sideways than following the traditional upward trend for this time of year.

(2016 enters near record low extent ranges on October 17 of 2016. Green dashed line represents 2012 sea ice extent, blue line represents 2007, black line the 1981 to 2010 average, orange line 2003, blue line 1994, and yellow line 1980. The gray border represents the 2 standard deviation from trend boundary. Image source: NSIDC.)
Trend lines for 2016 are also now within 90,000 square kilometers of exceeding previous record lows for sea ice extent set in 2007 and nearly matched in 2012 for the date of October 17.
Big Arctic Temperature Spike Driving Losses

Over the next few days, GFS model runs predict that a strong warming trend will take hold over the Arctic Ocean environment. As a result, temperature anomalies for the region above 66 North are expected to again spike to near 5 C above average for this time of year.
Given this predicted heat build-up, it’s certainly possible that refreeze rates will continue to be inhibited and that new record daily lows will be breached this week. Meanwhile, the overall trend for 2016 from January through middle October shows a year that is likely to see the lowest averaged levels of sea ice ever recorded for an entire year.
(Arctic temperatures have remained high throughout the fall — which has contributed to a very slow sea ice re-freeze so far. By Sunday, GFS model runs predict that temperatures over the Arctic Ocean will again push into much warmer than normal ranges for this time of year — possibly further delaying this region’s return to an ice-covered state. Image source: Climate Reanalyzer.)

Polar Amplification in Evidence

Loss of sea ice is a primary feature of polar amplification in the Arctic due to human-forced climate change.  Under polar amplification, warming of this region occurs faster than in the rest of the world. During summer, lower sea ice levels allow more sunlight to be absorbed by dark ocean waters — which preferentially traps heat in the Arctic environment. Less ice coverage during winter allows ocean heat to re-radiate into the Arctic which provides a significant boost to temperatures during the cold season.
mean-t-dmi-arctic-warmth-anomalous
(Anomalously warm temperatures over the Arctic Ocean have represented more a strange hybrid between fall and summer than a typical drop-off toward winter patterns during 2016. In the graph above, global warming appears to have basically levitated temperatures in the region above 80 North right off the chart. Image source: DMI.)

Last year, a never-before-seen late December warming of the Arctic pushed temperatures at the North Pole above freezing. If human fossil fuel burning continues and greenhouse gas accumulations in the Earth’s atmosphere keep rising, the Arctic is in for more dramatic fall, winter, and spring warming events than even those it is experiencing today. And with global temperatures entering a range of 1-2 C above preindustrial averages, the risk of a complete loss of Arctic sea ice over the coming years is on the rise.
Links:

Hat tip to Colorado Bob
Hat tip to Marcel Guldemond



No comments:

Post a Comment