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Shrinking Arctic ice linked to record dumps of snow

Adam Morton
February 28, 2012.

A DRAMATIC decline in Arctic sea ice linked to global warming is likely to have triggered record snow dumps in the northern hemisphere in recent winters, a study has found.

American and Chinese scientists found the drop in autumn Arctic sea ice - down by nearly a third since 1979 - caused changes in atmospheric circulation that contributed to freezing winters in China in 2007-08 and the US and Europe between 2009 and 2011.

In each case, large areas were hit by heavy snow, icy rain and cold temperatures that disrupted transport and energy supplies and damaged agriculture.

Study lead author Jiping Liu, a senior research scientist at the Georgia Institute of Technology, said the diminished Arctic ice cover led to weaker than usual westerly winds blowing across the Atlantic Ocean from Canada to Europe. ''It has made it easier for the cold Arctic air mass getting into mid and low-latitudes,'' he told The Age.

Published in US journal Proceedings of the National Academy of Sciences, the study also found the drop in sea ice and increase in open water had boosted the amount of moisture transferred from ocean to atmosphere, effectively giving it more snow to dump. ''If the Arctic sea ice continues to decline, probably we will see more consistent snow storms in the northern continents,'' Dr Liu said.

The decline in Arctic sea ice has outpaced climate models. The past five northern summers have been the five lowest for sea ice cover since satellite data was first collected in the 1970s - a reflection that Arctic temperatures have risen nearly twice as fast as the global average.

A US National Centre for Atmospheric Research computer simulation study recently estimated that about half of the ice loss between 1979 and 2005 was due to human greenhouse gas emissions and half natural variability.

Dr Liu said the study linking sea ice cover and extreme winter weather drew on both observational data and computer models that factored in snow cover, sea level pressure, surface air temperature and humidity.

He said the findings may help forecasting of snow and temperature anomalies.

US National Snow and Ice Data Centre director Mark Serreze has said that reports and aircraft reconnaissance indicated the recent summer sea ice levels were the lowest since 1900.

Analyses of ancient material have suggested it was likely to be at the lowest level since the end of the last glacial period about 8000 years ago.

The Arctic was ice free in the interglacial period about 125,000 years ago.

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More Related Coverage

Climate change is set to shake the earth
28 Feb A changing climate isn't just about floods, droughts and heatwaves. It brings erupting volcanoes and catastrophic earthquakes, says Bill McGuire in London.
http://www.smh.com.au/environment/climate-change/climate-change-is-set-to-shake-the-earth-20120228-1tzr2.html

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Copyright © 2012 Fairfax Media

http://www.smh.com.au/environment/climate-change/shrinking-arctic-ice-linked-to-record-dumps-of-snow-20120227-1tyzl.html


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Less sea ice brings more snow


Loss of Arctic sea ice cover between 1979 and 2010 coincided with more winter snow in parts of the United States, China and Europe (redder areas indicate more snowfall attributable to sea ice loss).
Credit: Google Maps/Jiping Liu

A melting Arctic shifts atmospheric patterns across much of the Northern Hemisphere

By Devin Powell
Monday, February 27th, 2012

Global warming may be responsible for the Northern Hemisphere's recent bout of severe winters. As Arctic sea ice melts, it funnels cold air toward the equator and sets the stage for snow, a new study finds.

“When we have a dramatic reduction in sea ice, we end up with more snow,” says climate scientist Jiping Liu of the Georgia Institute of Technology in Atlanta and coauthor of the study, published online February 27 in the Proceedings of the National Academy of Sciences.

Despite rising global temperatures, extreme winters have blasted much of the Northern Hemisphere during the last decade. Unusually large snowstorms pummeled the United States’ east coast during the winters of 2009 to 2010 and 2010 to 2011. Parts of Japan saw record levels of snow this winter, while in Europe both the Danube and Venice's canals froze over, a rare sight.

To explain this bitter cold and snow, some scientists have turned to natural climate fluctuations — including El Niño, a periodic warming of the eastern Pacific Ocean thought to portend warmer and drier winter conditions. But since some severe winters coincided with El Niño years, Liu's team looked instead to sea ice floating in the Arctic, a region that has been warming twice as quickly as the average rate for the Northern Hemisphere.

Satellite observations show that the amount of sea ice during autumn months, after the summer melt, declined by 27.3 percent between 1979 and 2010. In its worst year, 2007, sea ice covered 4.13 million square kilometers in September, down 1.19 million square kilometers from the previous record low in 2005. Years with less autumn ice tended to be followed by more winter snow in many parts of the Northern Hemisphere. The researchers’ computer simulations suggest that losing 1 million square kilometers of ice can increase snowfall by 3 to 12 percent in some places, including parts of the United States, Europe and China.

Liu and his team “confirm a link between sea-ice cover and snow cover,” says Ralf Jaiser, a climate scientist at the Alfred Wegener Institute for Polar and Marine Research in Potsdam, Germany. “That is something I always expected but was not able to prove.”

Raiser and other scientists have been studying the atmosphere to work out how changes in sea ice could chill faraway places. When the reflective ice disappears, the darker ocean that remains absorbs more of the sun's energy. Both the surface of the water and the air above it heat, changing the way that winds circulate through the atmosphere and forming a high-pressure system.

Computer simulations published in 2009 in Geophysical Research Letters found that such a pressure system can push cold air out of the Arctic and into Eurasia. A case study of Europe’s 2005-2006 winter, reported in 2010 in the Journal of Geophysical Research, suggested that cold air blowing in from the Arctic increases by threefold the chance of cold winter extremes in Europe.

Disappearing sea ice may also provide more moisture for forming snow, says Liu. In further simulations by his team, open water no longer covered by ice released vapor that traveled to parts of Europe and Asia.

But Stephen Vavrus, a climate scientist at the University of Wisconsin-Madison, doubts that this humidity plays much of a role. Most of the United States would have abnormally low humidity during the winter, based on the data of Liu’s team, in precisely the areas where lots of snow falls. “Whether there is enough moisture to cause heavy snowfall during a cold interval is probably controlled by other factors,” says Vavrus.

And disappearing sea ice isn’t only thing driving the cold and the snow. The United States had a particularly warm and snowless winter this year, probably thanks to a periodic flip in Arctic winds that trumped the effects of sea ice loss, says Liu.

Still, if sea ice melts further, big snowstorms may be in the forecast more often than not. “If this pattern of reduced sea ice continues, in the short term we may see more of these cold, snowy conditions,” says Radley Horton, a climate scientist at Columbia University who collaborated with Liu.

© Society for Science & the Public 2012

http://www.sciencenews.org/view/generic/id/338792/title/Less_sea_ice_brings_more_snow [with comments]


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Freezing winters ahead due to melting Arctic Sea ice

Britain faces years of freezing winters because global warming is causing Arctic Sea ice to melt, researchers have found.
27 Feb 2012
http://www.telegraph.co.uk/earth/earthnews/9109106/Freezing-winters-ahead-due-to-melting-Arctic-Sea-ice.html


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Much to Savor, and Worry About, Amid Mild Winter’s Early Blooms


Scenes more like spring, including a Japanese flowering apricot tree, arrived early at the New York Botanical Garden.


By LISA W. FODERARO
February 26, 2012

At the New York Botanical Garden [ http://www.nybg.org/ ] in the Bronx, an experimental plot was in full flower on a recent February afternoon, as the thermometer edged toward 60.

The Japanese camellias, which typically bloom in early spring, have displayed their rose-hued flowers continuously since December. Honeybees, a rarity before late March, were nursing the tiny pink clusters on a Dawn viburnum, while the Adonis amurensis, a ground-hugging spring ephemeral, was a profusion of yellow.

“This is the earliest I’ve seen all of these things in flower,” said Todd Forrest, the garden’s vice president for horticulture and living collections. “The ground isn’t even frozen. That’s shocking.”

The horticulturalists in the Bronx call it the global-warming garden, and in a winter notable for its consistent mildness, it is hardly unusual. From the Shakespeare Garden [ http://www.centralparknyc.org/visit/things-to-see/great-lawn/shakespeare-garden.html ] in Central Park to the Chicago Botanic Garden [ http://www.chicagobotanic.org/ ], flowering bulbs and other plants are bursting out two to four weeks ahead of schedule. Snowdrops are up; daffodils, crocuses and hellebores are already in flower; trailing phlox has opened; and, farther afield, even magnolia trees are starting to bloom on the National Mall in Washington.

Complaining about balmy winter days and an early display of color might seem churlish, but the early run of warm weather is not without its downside.

For one thing, if there is a cold snap, plants and trees are vulnerable to damaged blossoms and, potentially, a falloff in seed production. With the ground still soft in many places and no snow cover, squirrels — already suffering from the acorn shortage [ http://www.nytimes.com/2011/12/03/nyregion/boom-and-bust-in-acorns-will-affect-many-creatures-including-humans.html ] last fall — have been digging up bulbs. Populations of insect pests, normally kept in check by freezing temperatures, are expected to grow this year.

And when spring finally does arrive a month from now — according to the calendar anyway — the show might be ho-hum. “You’ll see a long, gradual kind of spring,” said Maria Hernandez, director of horticulture for the Central Park Conservancy [ http://www.centralparknyc.org/ ]. “But it won’t be the pizazz that we had last spring.”

Then there is the unavoidable question of climate change [ http://topics.nytimes.com/top/news/science/topics/globalwarming/index.html ].

It is hard to draw conclusions about the pace of warming from a single winter, and indeed, the last decade in New York City has been one of the snowiest on record. Still, Fred Gadomski, a meteorologist at Pennsylvania State University, said that temperatures were above normal in 80 percent of the days in the past three months in the city. Strong winds from the Pacific Ocean have blanketed most of the country with unusually mild air.

“That’s the distinguishing item this winter — the consistency of the mildness,” Mr. Gadomski said. “If you took away that week in mid-January where it really was sort of cold, it would be the year without a winter.”

Coincidentally, the federal Agriculture Department last month issued a new national map showing plant hardiness zones [ http://planthardiness.ars.usda.gov/PHZMWeb/ (below)],

which start with the coldest regions in the north and work their way south. In its first update since 1990, the map showed clear signs of things’ heating up. New York City, for instance, moved into a warmer zone, going from a “warm 6” to a “cold 7,” as Mr. Forrest put it.

David W. Wolfe, a professor of plant and soil ecology at Cornell University and an expert on climate change, said the temperatures this winter appeared to “represent an extreme,” even within the context of climate change. But, he said, the federal climate-zone guides from 1960, 1990 and this year reveal “an extremely fast pace” of change.

“This winter, when they do the final analysis, will be close to an all-time record breaker,” Dr. Wolfe said. “It’s a rare event. But I think it will become less rare.”

That is little solace to farmers, horticulturalists and home gardeners, who have worried about their charges this winter. Rod Dressel Sr., who owns a 300-acre apple orchard in the Hudson Valley, said the buds on his trees were starting to swell. If the trees flower too early, a freeze could kill the blossoms and, with them, the promise of apples this fall.

“I’m looking at 52 degrees here,” he said. “We’re concerned the tree will think it’s spring way too early. History has shown that we’re vulnerable to frost damage right up into the middle of May.”

In parks and public gardens across the country, visitors and horticulturalists alike are marveling at the winter blooms and rooting for their survival.

What happens to a luscious pink magnolia blossom if temperatures plunge? “It just turns brown and ugly,” said Holly H. Shimizu, the executive director of the United States Botanic Garden [ http://www.usbg.gov/ ] in Washington.

She wishes she could tell the plants to slow down. “The buds are swelling on the shadblow trees and I want to say, ‘Hold on, don’t do it,’ ” she said. “If it gets cold fast, they could be damaged and won’t bloom again.”

One concern with premature flowers is pollination. While honeybees were in evidence at the New York Botanical Garden, there were fewer at the United States Botanic Garden. “When plants get in this off-kilter blooming, sometimes it doesn’t coincide with the life cycle of the pollinator,” Ms. Shimizu said. “If pollination doesn’t occur, then we don’t get the fruit production.”

Some visitors to public gardens have felt conflicted by the unexpected splashes of pink and yellow. Dennis Mardon, a high school math teacher in the Bronx, was relieved to find that the daffodil shoots had yet to burst at the New York Botanical Garden, especially after seeing a couple of dozen in bloom on the nearby Mosholu Parkway.

“On the one hand, it’s great to see flowers this early — it lifts your spirits,” said Mr. Mardon, a Bronx native and lifelong gardener. “On the other hand, it creates apprehension. Gardens need an opportunity to rest, and that’s what a good winter provides.”

Should the weather take a sudden turn, daffodils, crocuses and snowdrops should be able to withstand any freezing temperatures, even snow. Not so the Japanese apricots in the Ladies’ Border [ http://www.nybg.org/gardens/ladies-border/ ], the experimental plot at the botanical garden, which was redesigned in 2002 with plants that do well in places like North Carolina or Virginia, one or two hardiness zones south of New York.

The experimental garden could, over time, serve as a blueprint for a new world of horticulture. “This is not normal,” said Mr. Forrest, touring the garden in only a suit and tie and no overcoat. “If this becomes the new normal, then we have to change the way we think about the plants we use and how we protect them.”

© 2012 The New York Times Company

http://www.nytimes.com/2012/02/27/nyregion/amid-winter-blooms-wondering-what-that-means-for-spring.html


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