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The end of November and the Arctic is experiencing temperatures above freezing!!!
Another
Heatwave Hits Arctic
As
parts of Canada, Greenland and Russia are hit by -40 degrees
temperatures (anomalies at the bottom end of the scale), parts of the
Arctic are experiencing temperatures above freezing
(Anomalies at the top end of the scale), as illustrated by the image below.
(Anomalies at the top end of the scale), as illustrated by the image below.
30
November, 2014
Temperatures
in the Arctic are much higher than they used to be and this situation
further accelerates warming in the Arctic, due to a number of
feedbacks.
One
such feedbacks has been coined the ‘open doors feedback’. Indeed,
the situation is much like leaving the fridge door open. This allows
cold air to more easily move out of the fridge, i.e. the Arctic,
resulting in the cold temperatures over North America that have
received extensive news coverage in the media. At the same time, warm
air can move more easily into the fridge, i.e. the Arctic, and this
is one of the reasons why the Arctic is hit by temperatures that are
so much higher than what used to be normal.
The
situation has been described in a number of earlier posts such as
this one, as well in a recent interview with Jennifer Francis. As the
Arctic warms more rapidly than the rest of the world, there's less
temperature difference between the Arctic and the equator, resulting
in the jet stream going around the globe at a lower speed with more
elongated loops.
The
left chart on above image shows such an elongated loop going north
along the east coast of Greenland, then bending before Scandinavia
and moving over the north of Greenland, then going around the North
Pole and moving back to Scandinavia. This loop is not very visible on
the chart, because the jet stream moves faster along straight tracks,
and this chart highlights wind speed more than it highlights the path
of the jet stream. Yet, the shape of this loop is very important, as
it traps warmer air north of Greenland.
BTW,
a weaker jet stream also elevates the chance of heat waves elsewhere,
which can indirectly warm up the Arctic. Examples of this are heat
waves over the Gulf Stream as it crosses the Atlantic Ocean,
resulting in warmer water being carried into the Arctic Ocean, and
heat waves over Siberia and North America, resulting in warming up of
rivers that end in the Arctic Ocean.
Anyway,
to get back to the current heatwave, there are a number of reasons
why temperatures in the Arctic are so high at the moment. One of the
biggest reasons is ocean heat, which has reached very high levels,
especially in the North Atlantic, while the Gulf Stream keeps
transporting warmer water from the North Atlantic into the Arctic
Ocean (i.e. water that is warmer than the water in the Arctic Ocean).
This warms up the seafloor of the Arctic Ocean, resulting in methane
erupting from the seafloor, with a strong immediate local warming
impact in the Arctic, thus further accelerating warming in the Arctic
in another one of these self-reinforcing feedback loops, as pictured
in the image below.
Further
feedbacks that accelerate warming in the Arctic are discussed at the
feedbacks page.
Without
effective and comprehensive action, these feedbacks threaten to lead
to runaway warming, i.e. abrupt climate change causing mass death and
destruction, and resulting in extinction at massive scale, as
depicted in the image below and as described in this earlier post.
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