ClimateHQ: Hot or Not?: Arctic Ice Extent

Showing posts with label Arctic Ice Extent. Show all posts

Arctic Sea Ice Extent 2002-2016

Arctic sea ice extent from 2002 to 2016. This is the overall area covered by ice annually. From JAXA:

Sea Ice Extent since 1978

Thinning Antarctic ice sheets have contributed considerable fresh water to the ocean surrounding the continent, especially as basal fresh water releases. This cold fresh water has counterbalanced otherwise warming waters and caused Antarctic sea ice extent to increase since 1979. Note that this is sea ice extent, not volume, and not land glaciers. Data from NSIDC:

Extent of multi-year ice in the Arctic

Extent of thick, multi-year ice in the Arctic relative to 1-year old ice, dating back to 1984:

Source on the image.

Arctic High Pressure events displacing cold air to the south

Why is it so cold in part of the mid-latitudes such as Europe and eastern North America and at the same time so warm in the Arctic? Is this consistent with 'Global Warming?' As per data from NOAA and other researchers, the 2009-2010 winter saw the formation of one of the three largest Arctic high-pressure events in the historical record going back to 1850 (and it has reappeared so far for the 2010-2011 season). Unusually high pressure and warm temperatures (a blocking pattern) over the Arctic have acted to displace cold air to the south:

Numerous models and researchers have predicted that this may happen with decreasing ice cover in the Arctic. So while it has been cold over the mid-latitudes, Greenland for example, has been than 18-degrees (!) above average for the month of December 2010.

Arctic Ice: Extent of old ice

The extent of multi-year ice in the Arctic, from 1988 to 2010. This is a more accurate reading of ice in the Arctic than simply the overall areal extent of annual winter ice, which will vary depending on the year:

Arctic Ice Volume

Arctic ice volume - areal extent plus thickness - since 1979. This is a more accurate representation of ice in the arctic than simply areal extent:

Arctic Melt Season

The length of the Arctic melt season since 1979 as measured by NASA:

The Arctic Dipole

A little background. In the latter part of the 20th century, a new and never-before seen weather pattern emerged in the arctic region called the Arctic Dipole anomaly. Typically in the winter months, the Arctic Oscillation results in winds circulating around the pole in a circular fashion, keeping sea ice restricted to the Arctic Basin. Higher air temperatures in the lower arctic atmosphere have resulted in changes in atmospheric circulation in which the classic arctic high is shunted off to the side while south to north winds bring warmer air into the polar region and also push sea ice out into the general region of the North Atlantic. The mechanism is observed to be heating of the ocean in areas of extreme summer sea ice loss, directly impacting surface air temperatures over the Arctic Ocean. As a result, the Arctic Dipole has been increasingly evident in the arctic in recent years and months.

According to one researcher, "The Arctic Dipole pattern occurred in all summer months of 2007 and helped support the record 2007 summer reduction in sea ice extent (Overland et al., 2008). Fall 2008 through spring 2009 featured the old AO pattern. The new Arctic Dipole pattern re-appeared in June - July 2009, but the old AO pattern dominated in August - September, resulting in greater sea ice extent than in 2007 and 2008. The Arctic Dipole pattern was active again in October, inactive in November, and is reasserting itself this December."

Regardless of your viewpoint on climate change, the Arctic Dipole represents a fundamental new change in atmospheric circulation in the Northern Hemisphere, one that has not been seen before, and is appearing with increasing regularity. It's likely to help speed the loss of ice from the arctic region in coming years.