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August 14 2012

22:57

ESA CryoSat-2 Data Reveals Arctic Summer Sea Ice Loss 50 Percent Greater than Expected


Cryosat-2 measures 50 percent more loss of sea ice than models have predictedOur planet’s climate appears to be reaching a potential tipping point more rapidly than previously estimated, according to preliminary results from data obtained from new remote sensing equipment on the European Space Agency’s (ESA) CryoSat-2 satellite. Arctic summer sea ice is being lost at a rate 50 percent higher than most of the scenarios projected by leading climate scientists, according to a report from The Guardian.

Researchers are for the first time able to accurately measure the thickness of sea ice across the Arctic’s expanse thanks to new instruments aboard ESA’s CryoSat-2. Preliminary results indicate that 900 cubic kilometers of summer sea ice has been lost during the past year. Whereas Arctic summer sea ice thickness averaged between five to six meters a decade ago, it’s now just 1-3 meters thick.

Profound Changes in Store

“Preliminary analysis of our data indicates that the rate of loss of sea ice volume in summer in the Arctic may be far larger than we had previously suspected,” The Guardian quoted Dr. Seymour Laxon of the Centre for Polar Observation and Modelling at University College London (UCL), where CryoSat-2 data is being analysed. “Very soon we may experience the iconic moment when, one day in the summer, we look at satellite images and see no sea ice coverage in the Arctic, just open water.”

The complete, or near total, loss of Arctic summer sea ice for all or part of the year would have profound effects on climate and life both locally and globally. Energy, mineral resource and commerical fishing companies view the opening of the Arctic seas as a new frontier for natural resource extraction. It would also be a boon for shipping companies and maritime transport, as it would open up the Northwest Passage and other shorter, less costly routes between North America and Eurasia.

The effects on local and global climate and the environment are likely to pose serious challenges for human, other animal and plant populations, however. The loss and thinning of Artic ice coverage accelerates climate warming as there’s less white ice surface area to reflect sunlight and heat up into and beyond the earth’s atmosphere, which will result in an acceleration of ocean temperature increases.

That may cause submarine methane deposits to melt, evaporate and escape into the atmosphere, adding significantly to the greenhouse effect. The appearance of methane plumes has been reported in many areas, The Guardian’s Robin McKie notes.

The disappearnce of Arctic sea ice around the Greenland coast would likewise have potentially devastating effects. Coastal sea ice around Greenland helps keep terrestrial glaciers there bottled up. Their disappearance would open a clear path to the sea, accelerating their melting. That would lead to sea level rising faster than it has been.

Disappearing Arctic sea ice could also result in profound changes to weather patterns globally, including precipitation levels and timing.

“With the temperature gradient between the Arctic and equator dropping, as is happening now, it is also possible that the jet stream in the upper atmosphere could become more unstable,” UCL Professor Chris Rapley explained. “That could mean increasing volatility in weather in lower latitudes, similar to that experienced this year.”

CryoSat-2 Reveals Arctic Sea Ice Thickness for First Time

ESA’s CryoSat-2 is the first satellite built specifically to measure and analyze sea ice thickness. It was launched on April 8, 2010 on a Dneiper rocket from Baikonur cosmodrome in Kazakhstan. Painstakingly analyzing the accuracy of CryoSat-2′s measurements, ESA project scientists are confident that CryoSat’s maps of ice thickness are correct to within 10 cm.

“Before CryoSat, we could see summer ice coverage was dropping markedly in the Arctic,” Rapley continued. “But we only had glimpses of what was happening to ice thickness. Obviously if it was dropping as well, the loss of summer ice was even more significant. We needed to know what was happening – and now CryoSat has given us the answer. It has shown that the Arctic sea cap is not only shrinking in area but is also thinning dramatically.”

Varying throughout the year, Arctic sea ice cover has typically reached a maximum in March. The data received from CryoSat-2 enables researchers to clearly reveal the extent of Arctic sea ice loss over the past eight years, both in winter and summer.

In Summer 2004, Arctic sea ice thickness totaled about 13,000 cubic kilometers. That’s been reduced to 7,000 cubic kilometers this summer. Arctic summer sea ice cover would disappear in about a decade if the current average annual loss of some 900 cubic kilometers continues.

UCL’s Laxon emphasized the need for prudence when making predictions and jumping to conclusionos based on CryoSat-2 data given the complexity of the earth’s climate system. He noted that Arctic sea ice loss in winter was much slower, which partially compensates for the loss of summer sea ice.

Nonetheless, the trend in Arctic sea ice coverage is undeniably downward, and likely on a steeper slope than has been estimated. A study undertaken this year by EAS Cryo-Sat project team Professor Peter Wadham indicated that the volume of Artic summer sea ice has dropped 70% during the past 30 years.

“The Arctic is particularly vulnerable to the impact of global warming,” The Guradian quoted Rapley. “Temperatures there are rising far faster than they are at the equator. Hence the shrinking of sea-ice coverage we have observed. It is telling us that something highly significant is happening to Earth. The weather systems of the planet are interconnected so what happens in the high latitudes affects us all.”

Image credit: ESA

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

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