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January 31 2012

18:35

The Oceanic Conveyor Belt: Climate Change Tipping Points Being Reached in the Arctic, Western Boundary Ocean Currents


Accelerated changes in the Arctic are moving ocean currents poleward and threaten the oceanic conveyor belt

Two new research papers by authoritative climate research teams were announced this week — one on climate change tipping points being reached in the Arctic and a second on warming of long-distance, poleward-moving ocean currents. The results of the studies show that warming of both the Arctic and western boundary currents is happening faster than has been anticipated, prompting the researchers to publicly urge that efforts to adapt to abrupt climate change be intensified globally.

Climate Change Tipping Points in the Arctic

In “Abrupt climate change in the Arctic,” University of Western Australia (UWA) Ocean Institute researchers lead by director and Winthrop Professor Carlos Duarte found that the Arctic is warming at a rate three times faster than the global average, which has caused Arctic summer sea ice to melt and recede at a pace faster than researchers have forecast.

Arctic summer sea ice may be limited to the the waters off northern Greenland and Ellesmere Island in as short a period as the next decade, and is likely to disappear entirely by the middle of the century, according to a WA News report. The warming’s occurring so fast that it’s not only threatening Arctic ecosystems and traditional ways of life, the Arctic may change from being a net carbon sink to a net source of greenhouse gas emissions.

The fast warming Arctic is opening up new sea lanes and a bonanza of resource exploration and exploitation, as well as political controversy over resource rights. However, faster than anticipated warming and melting will also have “abrupt knock-on effects” across major world cities in northern mid-latitudes, a list that includes Beijing, Berlin, London, Moscow, New York and Tokyo. Tentatively linked is the occurrence of much colder winters in Europe.

Warming of Western Ocean Boundary Currents

Also published in Nature Climate Change, “Enhanced warming over the global subtropical western boundary currents,” is a global study of fast-moving, long-distance ocean currents, such as the Gulfstream, that distribute heat and moisture from warming tropical ocean waters globally.

Moving along the western boundaries of the world’s ocean basins, changes in water temperature of these currents also have significant, large-scale effects on climate globally. Releasing heat and moisture on their way from the equator to the poles, they affect atmospheric jet streams and mid-latitude storms and patterns, as well as ocean absorption of carbon dioxide.

Reconstructing and re-examining data sets using new methods, the research team found that “the post-1900 surface ocean warming rate over the path of these currents is two to three times faster than the global mean surface ocean warming rate. The accelerated warming is associated with a synchronous poleward shift and/or intensification of global subtropical boundary currents in conjunction with a systematic change in winds over both hemispheres.”

The faster than expected warming of these long-distance, poleward moving ocean currents “may reduce the ability of the oceans to absorb anthropogenic carbon dioxide over these regions,” according to the report’s authors. “Uncertainties in detection and attribution of these warming trends remain,” they note, “pointing to a need for a long-term monitoring network of the global western boundary currents and their extensions.”

The Oceanic Conveyor Belt and Climate Change

Though not stated by the authors, the increasing incidence of unusual extreme storms, such as 2011′s Hurricane Irene, which carried as far north as the US’ mid-Atlantic and New England regions, and Typhoon Washi, which struck the southern Philippine island of Mindanao, may be evidence of the faster than expected melting of Arctic ice and faster than expected warming of western ocean boundary currents.

Moreover, the changes in both Arctic sea ice and western boundary currents are both aspects of what’s now known as the “oceanic conveyor belt” – scientific knowledge that’s come to us thanks to groundbreaking hypothesizing, testing and research performed by Wallace Broecker.

The abruptness and scale of the climate changes that increasingly appear to be headed our way warrant much greater attention by world leaders and policy makers. While exaggerated for dramatic effect, they bring to mind the popular disaster film, “The Day after Tomorrow,” the science of which is based on a shutting down of the oceanic conveyor belt Broecker first theorized, and the occurrence of world-changing super-storms that bring on a new Ice Age in a matter of months.

As UWA’s Prof. Duarte was quoted as saying, “We need to stop debating the existence of tipping points in the Arctic and start managing the reality of dangerous climate change.”

 

Image credit: NASA Ocean Motion

May 06 2011

00:19

Rapid Arctic Climate Change Could Intensify Sea Level Rise, Analysis Warns


Rapidly changing arctic will contribute to increased sea level riseAnalysis from the Oslo-based Arctic Monitoring and Assessment Programme (AMAP) shows the pace of climate change in the Arctic is quickening and will significantly contribute to sea level rise by up to five feet by the end of the century.

AMAP will release its full report in Nuuk Greenland at next week’s ministerial meeting of the eight-nation Arctic Council.

“The observed changes in sea ice on the Arctic Ocean, in the mass of the Greenland Ice Sheet and Arctic ice caps and glaciers over the past 10 years are dramatic and represent an obvious departure from the long-term patterns,” AMAP said in a press statement.

The Intergovernmental Panel on Climate Change (IPCC) projected a purposefully conservative estimate of 7 to 23 inches of sea level rise by the end of the century in their 2007 Fourth Assessment Report. The Assessment warned that a rapid increase in ice melt from Antarctica or the Greenland ice sheet (which the IPCCC did not attempt to project) would push sea levels dramatically higher.

Several studies since the 2007 Fourth Assessment have shown telltale signs of just that sort of accelerating ice melt, and now the latest AMAP analysis adds to the warning that change is accelerating and will cause significant sea level rise. But like the IPCCC Assessment, the AMAP report says determining the full extent of sea level rise remains and open question, saying that ”high uncertainty surrounds estimates of future global sea level.”

Arctic warming double global average

The AMAP report describes the Arctic as a region undergoing rapid and accelerating change:

  • The Arctic has warmed at twice the rate of the global average since 1980.
  • Summer temperatures have been higher than at any time during the past 2,000 years.
  • The past five years have had higher surface temperatures than any five-year period since modern weather record-keeping began in 1880.
  • Snow cover and sea ice extent has decreased, while temperature of Arctic permafrost has increased by up to 3.6 degrees Fahrenheit in some areas.

The AMAP analysis also speaks of positive reinforcing feedbacks:

“There is now evidence that two components of the cryosphere — snow and sea ice — are interacting with the climate system to accelerate warming,” the report says.

With decreasing snow cover exposing the darker ground underneath, more heat is absorbed, causing increased melting. Similar reinforcing feedback is caused by decreased sea ice extent. As more open ocean is exposed, more heat is absorbed, accelerating the decrease in sea ice.

The AMAP reports projects a “nearly” ice-free Arctic within the 30 to 40 years.

Source:
ClimateWire (subscription required)

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May 06 2010

17:42

Freak April Rain Showers Hit Canadian Arctic

While the Gulf of Mexico continues to choke on oil from a man-made disaster, the Arctic is experiencing another form of man-made onslaught thanks to climate change. 

Late last month, British explorers hiking in the Canadian Arctic reported that their ice base off Ellef Ringnes Island had been hit by a three-minute rain shower.  A team of Canadian scientists camped about 145 km west also reported being hit by rain at the same time.

Pen Hadow, the British team's expedition director, told Reuters, "It's definitely a shocker ... the general feeling within the polar community is that rainfall in the high Canadian Arctic in April is a freak event."

Hadow, whose team is gathering data on the effects of climate change on the Arctic Ocean in the Catlin Arctic Survey, said that "scientists would tell us that we can expect increasingly to experience these sorts of outcomes as the climate warms."
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But the group was not expecting such a sudden reminder of the consequences of a warming Arctic.

Ice base manager Paul Ramsden said, "It is obviously quite worrying when you are camped out on ice. I felt distinctly nervous for a while because the consequences of getting wet here can be serious."

And the rain isn’t the only indicator that things are out of whack in the North.

Reuters reports:
“Hadow said the team carrying out the carbon dioxide experiments had noticed that ice was abnormally thin and was moving around more than they expected. The winds were stronger than usual.”

Tyler Fish, another team member, told CBC that "We worry that if it's too warm maybe some of the scientific samples will start to thaw ... or the food will get too warm and spoil."

 "We have been told there will be more unpredicted events like this as the climate of the region warms. Our team up there have already reported many locals people at Resolute have also been commenting on the unusual warmth of the winter this year," Pen Hadow added.

The Arctic is heating up three times more quickly than the rest of the Earth, and scientists have linked the higher temperatures to global warming pollution.

Scientists working in the Arctic say the thick multiyear ice covering the Arctic Ocean has essentially vanished, and U.S. data shows the 2009 ice cover was the third-lowest on record, after 2007 and 2008.

David Phillips, senior climatologist with Environment Canada, described the freak rain in the High Arctic in April as “really bizarre,” noting that 50 to 60 years of historical weather data show no signs of rainfall ever occurring in April in the High Arctic.

"My business is weird, wild and wacky weather, and this is up there among fish falling from the sky or Niagara Falls running dry," Phillips told CBC News.

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