ClimateHQ: Hot or Not?: Arctic Temperatures

Showing posts with label Arctic Temperatures. Show all posts

Changes in permafrost temperatures in multiple locations

Changes in 20m depth permafrost temperatures from multiple locations in the Arctic over a 40+ year period, showing permafrost thaw:

Source: NOAA

Greenland temperatures since 1880

Average temperatures in Greenland from 1880-2010, six different stations:

Source: NASA

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 Melt Season

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

Arctic Oscillation

Stratospheric cooling results in counterclockwise circulation around the North Pole (the Arctic Oscillation) to strengthen in winter, its positive phase, acting to keep the polar jet stream north of the 45th parallel. In its positive phase, the AO results in warmer winters in the US, Scandinavia, and Russia.

For more on the stratosphere, click on the 'Stratosphere Temperatures' category in the right column.

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.