A
record low in the Arctic sea ice extent occurred on September 16, 2012 and it
was the lowest in the satellite record which started in 1979. Even more
troubling was that this year also saw a record low in sea ice volume.
 |
| Click on the image for a high-resolution version. Image Credit: NSIDC. |
The
previous record minimum extent occurred in 2007. What was extraordinary about this year was
that weather conditions were not as favorable for melting as in 2007. That year was noted for long periods of
sunshine which allowed the ice to melt over much of the Arctic. This year came on the heels of a cold winter
in which the ice extent came close to normal.
There were more clouds and a powerful storm which hit the Arctic in
early August which helped to break up more of the thin ice.
 |
| Click on the image for a high-resolution version. Image Credit: Climate Central. |
Arctic
sea ice has been on the decline since the introduction of satellite monitoring
in 1979. This is illustrated by the
graphic above. In addition, the rate of
decline has been accelerating. In fact,
this year’s minima was half what it was at the start of the record. Notice that the ice minima for Antarctica
have increased only slightly during the same time. Far more ice is being lost in the Arctic than
in the Antarctic. This is not surprising
at this time because the Antarctic is a much colder environment. Ice mass is being lost in the Antarctic even
though the extent has increased slightly.
 |
| Annual sea ice minimum. Image Credit: Open Mind. |
Temperatures
in the Arctic have been warming at least twice as fast as global
temperatures. It is warmer now than at
any time is the last 2,000 years. What
is more disturbing is that the rate of warming has been faster in the last 30
years.
 |
| Image Credit: Skeptical Science. |
Clearly
the trends show that the Arctic sea ice is in a death spiral. At some point there will be a sea ice-free
summer. Could is all be from global
warming? The answer is that it is
related to the warming of the planet, but the evidence indicates that it is
also from the ice-albedo effect. Ice and
snow are highly reflective and can reflect up to 90% of the solar insolation (incoming
solar radiation). As the ice melts the
albedo (the radiation that is reflected) changes to about 10-25% from the
darker ocean. Thus the ocean absorbs far
more energy than the ice. The NASA video
below illustrates the effect:
Why
does the loss of sea ice matter?
The
loss of sea ice changes both the ecology and meteorology as well as the
climate. Just in the past year there
have been two powerful storms to hit the region; the one in November, 2011, was
described as epic, while the one in August was a very powerful storm. The loss of the ice and warming of the ocean
is already impacting larger mammals like polar bears and some species of
seals. Scientists are now discovering
numerous examples.
Peter
Sinclair has put together a great video of the Arctic sea ice and how it is
changing. Much of the change has
occurred in the past 30 years. This has
prompted some scientists to speculate that a sea ice-free summer could occur in
the next 15 years.
Video Credit: The Yale Forum on Climate Change & The Media.
I
like to think that the Arctic is like the “canary in the coal mine.” Nature is telling us that the changes are
occurring now and at an unprecedented pace.
The science is clear and we ignore it at our peril.
Other
articles on the Arctic situation can be found here:
and
