Tuesday, March 23, 2010

Wind Changes Associated with Arctic Sea Ice Losses

The first question to ask is whether this can be the whole answer for the decadal decline in total Arctic sea ice.  The switch itself took place at least forty years ago and the ice base has been rotting out ever since.  There is little reason to not argue that the changing ice is contributing to slightly stronger wind regimes as naturally follows even slightly warmer conditions.

I find it more convincing to assign motive rights to changes in the ocean itself which on average will be almost negligible but properly targeted can be very powerful.  An increase in the volume of warmer water into the Arctic for the past forty or so years would do the job nicely, yet be unnoticeable in the North Atlantic.

I recall that the top few meters carry as much heat as the whole atmosphere.  I do not recall the exact number but it is shockingly low. Enough to note that that small part is underlain by another couple of hundred meters of the ocean’s surface layer containing an ocean of additional heat.  It takes very little ocean to change the climate anywhere but particularly in the Arctic.

What makes the winds irrelevant and certainly a result of changing ocean conditions is that multiyear ice is not apparently accumulating and building up in the best locales.  That means that the underlying water is no longer assisting.

Winds or not, we are presently in the final stages of a massive collapse of the Arctic sea ice.  In fact this winter was astounding.  We entered it with the remaining sea ice largely rotten and collapsing almost everywhere observed.  While the southern part of the continent got hammered with lower that expected temperatures and the snow to go with it, the Arctic was a few degrees warmer than expected.  In fact all of Canada was a full four degrees Celsius warmer (around eight degrees Fahrenheit) which I find astonishing.

This means that ice recovery will have been far weaker than normal.  All of which suggests we could get a spectacular collapse of the surface area of the ice this year.  Summer warming will then be added to Arctic waters and will likely help sustain an ice free Arctic Sea afterwards.

Of course, Iceland’s volcanoes may well be about to put an end to all this.

Wind contributing to Arctic sea ice loss, study finds

New research does not question climate change is also melting ice in the Arctic, but finds wind patterns explain steep decline

Arctic sea ice as seen from Nasa satellites. Photograph: HO/AFP/Getty Images
Much of the record breaking loss of ice in the Arctic ocean in recent years is down to the region's swirling winds and is not a direct result of global warming, a new study reveals.

Ice blown out of the region by Arctic winds can explain around one-third of the steep downward trend in sea ice extent in the region since 1979, the scientists say.

The study does not question that global warming is also melting ice in the Arctic, but it could raise doubts about high-profile claims that the region has passed a climate "tipping point" that could see ice loss sharply accelerate in coming years.

The new findings also help to explain the massive loss of Arctic ice seen in the summers of 2007-08, which prompted suggestions that the summertime Arctic Ocean could be ice-free withing a decade. About half of the variation in maximum ice loss each September is down to changes in wind patterns, the study says.

Masayo Ogi, a scientist with the Japan Agency for Marine-Earth Science and Technology in Yokohama, and her colleagues, looked at records of how winds have behaved across the Arctic since satellite measurements of ice extent there began in 1979.
They found that changes in wind patterns, such as summertime winds that blow clockwise around the Beaufort Sea, seemed to coincide with years where sea ice loss was highest.
Writing in a paper to be published in the journal Geophysical Research Letters, the scientists suggest these winds have blown large amounts of Arctic ice south through the Fram Strait, which passes between Greenland and the Norwegian islands of Svalbard, and leads to the warmer waters of the north Atlantic. These winds have increased recently, which could help explain the apparent acceleration in ice loss.

"Wind-induced, year-to-year differences in the rate of flow of ice toward and through Fram Strait play an important role in modulating September sea ice extent on a year-to-year basis," the scientists say. "A trend toward an increased wind-induced rate of flow has contributed to the decline in the areal coverage of Arctic summer sea ice."
Ogi said this was the first time the Arctic winds have been analysed in such a way.
"Both winter and summer winds could blow ice out of the Arctic [through] the Fram Strait during 1979-2009," she said.
A number of other factors were also responsible for ice loss, including warming of the air and ocean, she added.
According to the National Snow and Ice Data Centre in Colorado, Arcticsea ice "is in a state of ongoing decline". Since 1979, the ice has shrunk by about 10% a decade, or 28,000 square miles each year. The ice reaches its minimum extent each September, when it begins to reform as the freezing Arctic winter takes hold.

Canada reports mildest winter on record

by Staff Writers

Montreal (AFP) March 19, 2010

Canada jumps into spring after having recorded the mildest and driest winter on record, Environment Canada reported Friday.

The agency, which has compiled data from 1948, determined the average temperature throughout the country was four degrees Celsius (seven degrees Fahrenheit) above normal, said meteorologist Andre Cantin.

Cantin said the country also saw 20 percent less precipitation than normal, also a record.

El Nino, the climate pattern in the Pacific Ocean that influences global weather, was likely responsible for the freakish weather, according to Cantin, who noted that changes in climate may also have played a role.

The unusual winter wreaked havoc at the Winter Olympics at venues near Vancouver, where a shortage of snow delayed many events.

Some Arctic areas were warmer and the north of Quebec province was six degrees Celsius (10 Fahrenheit) above the norm.

No comments: