tagged w/ Arctic ice melt
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Time to get louder at government about this. Time to win this conversation with truth. CO2 traps heat. One of the main points of this, plus some others I divulge. ;l). Thanks Current for this venue for us to tell it like it is.
This video is dedicated to the indigenous peoples of our world and those experiencing the brunt of the effects of climate change/biodistress. May we find it within us to do what is right for all.Time to get louder at government about this. Time to win this conversation with truth.... more
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Less ice covers the Arctic today than at any time in recent geologic history. That's the conclusion of an international group of researchers, who have compiled the first comprehensive history of Arctic ice.
For decades, scientists have strived to collect sediment cores from the difficult-to-access Arctic Ocean floor, to discover what the Arctic was like in the past. Their most recent goal: to bring a long-term perspective to the ice loss we see today.
Now, in an upcoming issue of Quarternary Science Reviews, a team led by Ohio State University has re-examined the data from past and ongoing studies - nearly 300 in all - and combined them to form a big-picture view of the pole's climate history stretching back millions of years.
"The ice loss that we see today - the ice loss that started in the early 20th Century and sped up during the last 30 years - appears to be unmatched over at least the last few thousand years," said Leonid Polyak, a research scientist at Byrd Polar Research Center at Ohio State University. Polyak is lead author of the paper and a preceding report that he and his coauthors prepared for the U.S. Climate Change Science Program.
Satellites can provide detailed measures of how much ice is covering the pole right now, but sediment cores are like fossils of the ocean's history, he explained.
"Sediment cores are essentially a record of sediments that settled at the sea floor, layer by layer, and they record the conditions of the ocean system during the time they settled. When we look carefully at various chemical and biological components of the sediment, and how the sediment is distributed - then, with certain skills and luck, we can reconstruct the conditions at the time the sediment was deposited."
For example, scientists can search for a biochemical marker that is tied to certain species of algae that live only in ice. If that marker is present in the sediment, then that location was likely covered in ice at the time. Scientists call such markers "proxies" for the thing they actually want to measure - in this case, the geographic extent of the ice in the past.
While knowing the loss of surface area of the ice is important, Polyak says that this work can't yet reveal an even more important fact: how the total volume of ice - thickness as well as surface area - has changed over time.
"Underneath the surface, the ice can be thick or thin. The newest satellite techniques and field observations allow us to see that the volume of ice is shrinking much faster than its area today. The picture is very troubling. We are losing ice very fast," he said.
"Maybe sometime down the road we'll develop proxies for the ice thickness. Right now, just looking at ice extent is very difficult."
To review and combine the data from hundreds of studies, he and his cohorts had to combine information on many different proxies as well as modern observations. They searched for patterns in the proxy data that fit together like pieces of a puzzle.
Their conclusion: the current extent of Arctic ice is at its lowest point for at least the last few thousand years.
As scientists pull more sediment cores from the Arctic, Polyak and his collaborators want to understand more details of the past ice extent and to push this knowledge further back in time.
During the summer of 2011, they hope to draw cores from beneath the Chukchi Sea, just north of the Bering Strait between Alaska and Siberia. The currents emanating from the northern Pacific Ocean bring heat that may play an important role in melting the ice across the Arctic, so Polyak expects that the history of this location will prove very important.
continuedLess ice covers the Arctic today than at any time in recent geologic history.... more
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Skepticism about climate change is going mainstream, and that is worrying. One-third of Americans now say global warming doesn’t exist – triple the percentage of three years ago. This defiance of science isn’t just harmful for the environment. It’s also distracting us from growing threats to US national security. Actual – not theoretical – effects of climate change are turning the Arctic into a potential military flash point.
Expected melting of summer sea ice in the Arctic Ocean means greatly expanded access to increasingly scarce fossil fuels. It also means tensions over Arctic real estate. What the Middle East was to the second half of the 20th century, the Arctic could be to the first half of the 21st. Because America has been so slow to wake up to climate change, it’s lagging behind in protecting its Arctic interests.
“Since 1995 we have lost 40 percent of the North Pole’s icecap,” said Professor Robert Huebert, of the University of Calgary and an adviser to the Canadian government. Mr. Huebert and other experts spoke at a recent conference on climate change security risks hosted by the Center for National Policy. “It is not a matter of if, but when, the ice will be gone,” he said.
Moscow gets this, even if the US public does not. “The Arctic must become Russia’s main strategic resource base,” Nikolai Patrushev, the secretary of the Russian Security Council, declared last year. “It cannot be ruled out that the battle for raw materials will be waged by military means,” a Russian planning document has warned.
Partially because of years of climate change denial, “the United States remains largely asleep at the wheel,” according to a Foreign Affairs article last March by Scott Borgerson, a fellow at the Council on Foreign Relations.
Meanwhile, other Arctic nations are moving to muscularly stake their sovereignty claims while prospecting for hundreds of billions of dollars of treasure buried on the ocean floor up there.
Major melting has spurred Russia, Canada, Denmark (via Greenland), and Norway into a new gold rush, except this time it’s about staking claim to huge reservoirs of natural gas, petroleum, and untold deposits of minerals previously inaccessible because of the polar ice shield. Much of the sub-sea Arctic wealth will of necessity be transported by ships because thawing tundra will be too unstable for pipelines. The South Koreans anticipated this more than a decade ago, building giant vessels to secure a big share of the shipping market.
The US and other Arctic nations are meeting this month to discuss Arctic sovereignty. Previous summits have included agreements to act responsibly and peacefully as the polar icecap recedes, but nearly all nations involved are rearming militarily to defend their sovereignty. “We are already in an Arctic arms race,” Huebert says. “The year 2010 in the Arctic is akin to 1935 in Europe.” Russia is building military bases on the Arctic coast and has 10,000 troops deployed near its northern border to assert its expanding claims.
cont.Skepticism about climate change is going mainstream, and that is worrying. One-third... more
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In 2007, the Arctic lost a massive amount of thick, multiyear sea ice, contributing to that year's record-low extent of Arctic sea ice. A new NASA-led study has found that the record loss that year was due in part to the absence of "ice arches," naturally-forming, curved ice structures that span the openings between two land points. These arches block sea ice from being pushed by winds or currents through narrow passages and out of the Arctic basin.
Beginning each fall, sea ice spreads across the surface of the Arctic Ocean until it becomes confined by surrounding continents. Only a few passages -- including the Fram Strait and Nares Strait -- allow sea ice to escape.
"There are a couple of ways to lose Arctic ice: when it flows out and when it melts," said lead study researcher Ron Kwok of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We are trying to quantify how much we're losing by outflow versus melt."
Kwok and colleagues found that ice arches were missing in 2007 from the Nares Strait, a relatively narrow 30- to 40-kilometer-wide (19- to 25-mile-wide) passage west of Greenland. Without the arches, ice exited freely from the Arctic. The Fram Strait, east of Greenland, is about 400 kilometers (249 miles) wide and is the passage through which most sea ice usually exits the Arctic.
Despite Nares' narrow width, the team reports that in 2007, ice loss through Nares equaled more than 10 percent of the amount emptied on average each year through the wider Fram Strait.
"Until recently, we didn't think the small straits were important for ice loss," Kwok said. The findings were published this month in Geophysical Research Letters.
"One of our most important goals is developing predictive models of Arctic sea ice cover," said Tom Wagner, cryosphere program manager at NASA Headquarters in Washington. "Such models are important not only to understanding changes in the Arctic, but also changes in global and North American climate. Figuring out how ice is lost through the Fram and Nares straits is critical to developing those models."
To find out more about the ice motion in Nares Strait, the scientists examined a 13-year record of high-resolution radar images from the Canadian RADARSAT and European Envisat satellites. They found that 2007 was a unique year – the only one on record when arches failed to form, allowing ice to flow unobstructed through winter and spring.
The arches usually form at southern and northern points within Nares Strait when big blocks of sea ice try to flow through the strait's restricted confines, become stuck and are compressed by other ice. This grinds the flow of sea ice to a halt.
"We don't completely understand the conditions conducive to the formation of these arches," Kwok said. "We do know that they are temperature-dependent because they only form in winter. So there's concern that if climate warms, the arches could stop forming."
To quantify the impact of ice arches on Arctic Ocean ice cover, the team tracked ice motion evident in the 13-year span of satellite radar images. They calculated the area of ice passing through an imaginary line, or "gate," at the entrance to Nares Strait. Then they incorporated ice thickness data from NASA's ICESat to estimate the volume lost through Nares.
They found that in 2007, Nares Strait drained the Arctic Ocean of 88,060 square kilometers (34,000 square miles) of sea ice, or a volume of 60 cubic miles. The amount was more than twice the average amount lost through Nares each year between 1997 and 2009.
The ice lost through Nares Strait was some of the thickest and oldest in the Arctic Ocean.
"If indeed these arches are less likely to form in the future, we have to account for the annual ice loss through this narrow passage. Potentially, this could lead to an even more rapid decline in the summer ice extent of the Arctic Ocean," Kwok said.In 2007, the Arctic lost a massive amount of thick, multiyear sea ice, contributing to... more
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Global warming — the very term sounds gentle, like a bath that grows pleasantly hotter under the tap. Many people might assume that's how climate change works too, the globe gradually increasing in temperature until we decide to stop it by cutting our carbon emissions. It's a comforting notion, one that gives us time to gauge the steady impact of warming before taking action.
There's just one problem: that's not how climate change is likely to unfold. Instead, scientists worry about potential tipping points — triggers that, once reached, could lead to sudden and irrevocable changes in the climate, almost without warning. It's the same phenomenon of sudden collapse that can be seen in any number of complex systems that seem perfectly stable, until they're not — ecosystems, financial markets, even epileptic seizures. The trick is to identify the warning signs that indicate a tipping point — and collapse — are about to be reached and to take action to avoid them.
(Read "Heroes of the Environment 2008.")
A new article in the Sept. 3 issue of Nature shows there may be ways to do this, since certain warning signals appear to be similar across a variety of complex systems. Researchers from Wageningen University, the University of Wisconsin and Scripps Institution of Oceanography found that an assortment of systems they studied all had critical thresholds that could trigger change from one state to another — changes that tend to be abrupt, not gradual. "Such threshold events don't happen that often, but they are extraordinarily important," says study co-author Stephen Carpenter of the University of Wisconsin. "They are the portals to change."
So, how do we know that change is at hand? The Nature researchers noticed one potential signal: the sudden variance between two distinct states within one system, known by the less technical term squealing. In an ecological system like a forest, for example, squealing might look like an alternation between two stable states — barren versus fertile — before a drought takes its final toll on the woodland and transforms it into a desert, at which point even monsoons won't bring the field back to life. Fish populations seem to collapse suddenly as well — overfishing causes fluctuations in fish stocks until it passes a threshold, at which point there are simply too few fish left to bring back the population, even if fishing completely ceases. And even in financial markets, sudden collapses tend to be preceded by heightened trading volatility — a good sign to pull your money out of the market. "Heart attacks, algae blooms in lakes, epileptic attacks — every one shows this type of change," says Carpenter. "It's remarkable."
(See TIME's video: "Climate Central: Vanishing Salt Marshes.")
In climate terms, squealing may involve increased variability of the weather — sudden shifts from hot temperatures to colder ones and back again. General instability ensues and, at some point, the center ceases to hold. "Before we reached a climate tipping point we'd expect to see lots of record heat and record cold," says Carpenter. "Every example of sudden climate change we've seen in the historical record was preceded by this sort of squealing."
The hard part will be putting this new knowledge into action. It's true that we have a sense of where some of the tipping points for climate change might lie — the loss of Arctic sea ice, or the release of methane from the melting permafrost of Siberia. But that knowledge is still incomplete, even as the world comes together to try, finally, to address the threat collectively. "Managing the environment is like driving a foggy road at night by a cliff," says Carpenter. "You know it's there, but you don't know where exactly." The warning signs give us an idea of where that cliff might be — but we'll need to pay attention.
more at the linkGlobal warming — the very term sounds gentle, like a bath that grows pleasantly... more
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While it's still too early to say whether the 2009 melt will exceed the record 2007 melt -- the annual low-point isn't reached until September -- the trend line for 2009 for the first time has dipped below 2007, according to the latest data from the National Snow and Ice Data Center.
Another record would be startling, but not surprising. Just 30% of the sea ice in the Arctic at the height of the winter freeze was thicker multi-year ice, leaving 70% susceptible to rapid melting. The amount of ice in the Arctic as of February 2009 -- the height of the annual freeze -- was the lowest on record. Most arctic scientists now say they expect an ice-free Arctic in summer within the next three decades -- far ahead of the projections in the last comprehensive United Nations report on global warming.
The melting of Arctic sea ice is one of the clearest signals of global warming, and a leading indicator of what is to come. The melting is also an example -- one of many -- of a positive feedback loop that scientists expect will accelerate global warming: As sea ice melts, the darker water that is exposed absorbs more of the sun's energy, which leads to warmer waters and more melting ice.
end of excerptWhile it's still too early to say whether the 2009 melt will exceed the record... more
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