Posts tagged Arctic Ocean
Ice-free Arctic winters could explain amplified warming during Pliocene
Jul 29th
Year-round ice-free conditions across the surface of the Arctic Ocean could explain why the Earth was substantially warmer during the Pliocene Epoch than it is today, despite similar concentrations of carbon dioxide in the atmosphere, according to new research carried out at the University of Colorado Boulder.
The last time researchers believe the carbon dioxide concentration in the atmosphere reached 400 ppm—between 3 and 5 million years ago during the Pliocene—the Earth was about 3.5 to 9 degrees Fahrenheit warmer (2 to 5 degrees Celsius) than it is today. During that time period, trees overtook the tundra, sprouting right to the edges of the Arctic Ocean, and the seas swelled, pushing ocean levels 65 to 80 feet higher.
Scientists’ understanding of the climate during the Pliocene has largely been pieced together from fossil records preserved in sediments deposited beneath lakes and on the ocean floor.
“When we put 400 ppm carbon dioxide into a model, we don’t get as warm a planet as we see when we look at paleorecords from the Pliocene,” said Jim White, director of CU-Boulder’s Institute of Arctic and Alpine Research and co-author of the new study published online in the journal Palaeogeography, Paleoclimatology, Palaeoecology. “That tells us that there may be something missing in the climate models.”
Scientists have proposed several hypotheses in the past to explain the warmer Pliocene climate. One idea, for example, was that the formation of the Isthmus of Panama, the narrow strip of land linking North and South America, could have altered ocean circulations during the Pliocene, forcing warmer waters toward the Arctic. But many of those hypotheses, including the Panama possibility, have not proved viable.
For the new study, led by Ashley Ballantyne, a former CU-Boulder doctoral student who is now an assistant professor of bioclimatology at the University of Montana, the research team decided to see what would happen if they forced the model to assume that the Arctic was free of ice in the winter as well as the summer during the Pliocene. Without these additional parameters, climate models set to emulate atmospheric conditions during the Pliocene show ice-free summers followed by a layer of ice reforming during the sunless winters.
“We tried a simple experiment in which we said, ‘We don’t know why sea ice might be gone all year round, but let’s just make it go away,’ ” said White, who also is a professor of geological sciences. “And what we found was that we got the right kind of temperature change and we got a dampened seasonal cycle, both of which are things we think we see in the Pliocene.”
In the model simulation, year-round ice-free conditions caused warmer conditions in the Arctic because the open water surface allowed for evaporation. Evaporation requires energy, and the water vapor then stored that energy as heat in the atmosphere. The water vapor also created clouds, which trapped heat near the planet’s surface.
“Basically, when you take away the sea ice, the Arctic Ocean responds by creating a blanket of water vapor and clouds that keeps the Arctic warmer,” White said.
White and his colleagues are now trying to understand what types of conditions could bridge the standard model simulations with the simulations in which ice-free conditions in the Arctic are imposed. If they’re successful, computer models would be able to model the transition between a time when ice reformed in the winter to a time when the ocean remained devoid of ice throughout the year.
Such a model also would offer insight into what could happen in our future. Currently, about 70 percent of sea ice disappears during the summertime before reforming in the winter.
“We’re trying to understand what happened in the past but with a very keen eye to the future and the present,” White said. “The piece that we’re looking at in the future is what is going to happen as the Arctic Ocean warms up and becomes more ice-free in the summertime.
“Will we continue to return to an ice-covered Arctic in the wintertime? Or will we start to see some of the feedbacks that now aren’t very well represented in our climate models? If we do, that’s a big game changer.”
CU-Boulder geological sciences Professor Gifford Miller also is a co-author of the study. Researchers from Northwestern University and the National Center for Atmospheric Research also were involved in the study, which was supported by a grant from the National Science Foundation.
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And the 2012 Rubber Dodo Award goes to…Climate-change Denying Senator James Inhofe
Oct 26th
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TUCSON, Ariz.— Senator James Inhofe, one of Congress’ staunchest deniers of climate change and stalwart human obstacle to federal action on this unprecedented global crisis, is the lucky recipient of the Center for Biological Diversity’s 2012 Rubber Dodo Award, which is given annually to those who have done the most to drive endangered species extinct. Previous winners include the U.S. Chamber of Commerce (2011), former BP CEO Tony Hayward (2010), massive land speculator Michael Winer (2009), Alaska Gov. Sarah Palin (2008) and Interior Secretary Dirk Kempthorne (2007). When it comes to denying the climate crisis — the single-greatest threat now facing life on Earth — James Inhofe has few peers. The Oklahoma Republican is the ringleader of anti-science climate-deniers in Congress and a driving force behind the tragic lack of U.S. action to tackle this complex problem. 2012 saw the publication, to resoundingly little critical acclaim, of Sen. Inhofe’s book, The Greatest Hoax: How the Global Warming Conspiracy Threatens Your Future, by WND Press, an entity also known for its “birther” campaign against President Barack Obama.
“As climate change ravages the world, Senator Inhofe insists that we deny the reality unfolding in front of us and choose instead to blunder headlong into chaos,” said Kierán Suckling, the Center’s executive director. “Senator Inhofe gets the 2012 Rubber Dodo Award for being at the vanguard of the retrograde climate-denier movement.” This year is on track to become the warmest on record; some 40,000 temperature records have been broken in the United States in 2012 alone, while Arctic sea ice has melted to a record low. The year has also seen record droughts, crop failures, massive wildfires, floods and other unmistakable signals that manmade global warming is tightening its grip, threatening people and wildlife around the globe. “Senator Inhofe’s pet theory that climate change is an elaborate hoax would be hilarious, if only he weren’t an elected representative of the American people,” Suckling said. “If he were, say, a performance artist, it’d be really funny. But sadly he has the power to affect U.S. climate policy. The United States has a chance — and a duty — to take significant steps to slow the climate crisis, and a brief window of time before it’s too late for us to do so. Deniers like Inhofe, in positions of leadership, are dooming future generations of people to a far more difficult world.”
More than 15,000 people cast their votes in this year’s Rubber Dodo contest. Other official nominees were Sen. Jon Tester of Montana, who put a rider on a must-pass bill that stripped Endangered Species Act protection from wolves, and Shell Oil, a company bound and determined to pursue dangerous oil drilling in the Arctic Ocean. Background on the Dodo Its trusting nature led to its rapid extinction. By 1681 the dodo was extinct, having been hunted and outcompeted by humans, dogs, cats, rats, macaques and pigs. Humans logged its forest cover while pigs uprooted and ate much of the understory vegetation. The origin of the name dodo is unclear. It likely came from the Dutch word dodoor, meaning “sluggard,” the Portuguese word doudo, meaning “fool” or “crazy,” or the Dutch word dodaars meaning “plump-arse” (that nation’s name for the little grebe). The dodo’s reputation as a foolish, ungainly bird derives in part from its friendly naiveté and the very plump captives that were taken on tour across Europe. The animal’s reputation was cemented with the 1865 publication of Lewis Carroll’s Alice’s Adventures in Wonderland. Based on skeleton reconstructions and the discovery of early drawings, scientists now believe that the dodo was a much sleeker animal than commonly portrayed. The rotund European exhibitions were accidentally produced by overfeeding captive birds. The Center for Biological Diversity is a national, nonprofit conservation organization with more than 450,000 members and online activists dedicated to the protection of endangered species and wild places. |
Arctic sea ice reaches lowest extent ever recorded, says CU-Boulder research team
Aug 27th
The blanket of sea ice floating on the Arctic Ocean melted to its lowest extent ever recorded since satellites began measuring it in 1979, according to the University of Colorado Boulder’s National Snow and Ice Data Center.
On Aug. 26, the Arctic sea ice extent fell to 1.58 million square miles, or 4.10 million square kilometers. The number is 27,000 square miles, or 70,000 square kilometers below the record low daily sea ice extent set Sept. 18, 2007. Since the summer Arctic sea ice minimum normally does not occur until the melt season ends in mid- to late September, the CU-Boulder research team expects the sea ice extent to continue to dwindle for the next two or three weeks, said Walt Meier, an NSID scientist.
“It’s a little surprising to see the 2012 Arctic sea ice extent in August dip below the record low 2007 sea ice extent in September,” he said. “It’s likely we are going to surpass the record decline by a fair amount this year by the time all is said and done.”
On Sept. 18, 2007, the September minimum extent of Arctic sea ice shattered all satellite records, reaching a five-day running average of 1.61 million square miles, or 4.17 million square kilometers. Compared to the long-term minimum average from 1979 to 2000, the 2007 minimum extent was lower by about a million square miles — an area about the same as Alaska and Texas combined, or 10 United Kingdoms.
While a large Arctic storm in early August appears to have helped to break up some of the 2012 sea ice and helped it to melt more quickly, the decline seen in in recent years is well outside the range of natural climate variability, said Meier. Most scientists believe the shrinking Arctic sea ice is tied to warming temperatures caused by an increase in human-produced greenhouse gases pumped into Earth’s atmosphere.
CU-Boulder researchers say the old, thick multi-year ice that used to dominate the Arctic region has been replaced by young, thin ice that has survived only one or two melt seasons — ice which now makes up about 80 percent of the ice cover. Since 1979, the September Arctic sea ice extent has declined by 12 percent per decade.
The record-breaking Arctic sea ice extent in 2012 moves the 2011 sea ice extent minimum from the second to the third lowest spot on record, behind 2007. Meier and his CU-Boulder colleagues say they believe the Arctic may be ice-free in the summers within the next several decades.
“The years from 2007 to 2012 are the six lowest years in terms of Arctic sea ice extent in the satellite record,” said Meier. “In the big picture, 2012 is just another year in the sequence of declining sea ice. We have been seeing a trend toward decreasing minimum Arctic sea ice extents for the past 34 years, and there’s no reason to believe this trend will change.”
The Arctic sea ice extent as measured by scientists is the total area of all Arctic regions where ice covers at least 15 percent of the ocean surface, said Meier.
Scientists say Arctic sea ice is important because it keeps the polar region cold and helps moderate global climate — some have dubbed it “Earth’s air conditioner.” While the bright surface of Arctic sea ice reflects up to 80 percent of the sunlight back to space, the increasing amounts of open ocean there — which absorb about 90 percent of the sunlight striking the Arctic — have created a positive feedback effect, causing the ocean to heat up and contribute to increased sea ice melt.
Earlier this year, a national research team led by CU embarked on a two-year effort to better understand the impacts of environmental factors associated with the continuing decline of sea ice in the Arctic Ocean. The $3 million, NASA-funded project led by Research Professor James Maslanik of aerospace engineering sciences includes tools ranging from unmanned aircraft and satellites to ocean buoys in order to understand the characteristics and changes in Arctic sea ice, including the Beaufort Sea and Canada Basin that are experiencing record warming and decreased sea ice extent.
NSIDC is part of CU-Boulder’s Cooperative Institute for Research in Environmental Sciences — a joint institute of CU-Boulder and the National Oceanic and Atmospheric Administration headquartered on the CU campus — and is funded primarily by NASA. NSIDC’s sea ice data come from the Special Sensor Microwave Imager/Sounder sensor on the Defense Meteorological Satellite Program F17 satellite using methods developed at NASA’s Goddard Space Flight Center in Greenbelt, Md.
For more information and graphics visit CU-Boulder’s NSIDC website at http://nsidc.org/arcticseaicenews/2011/091511.html. For more information on CIRES visithttp://cires.colorado.edu/.
