Colder Winters Caused By Warmer Summers, Research Suggests
International scientists have some bad news for those wondering when global warming will kick in during Canadian winters.
Researchers suggest that rising temperatures during the other three seasons are actually cooling off winters in North America — all because of snowfall in Siberia and an atmospheric pressure pattern in high latitudes called the Arctic Oscillation.
"When you have more snow cover in October across Eurasia, you have this negative phase of the Arctic Oscillation," said lead author Judah Cohen of Atmospheric and Environmental Research, a weather research company, whose paper was published Thursday in Environmental Research Letters.
"When you have a negative Arctic Oscillation, southern Canada, the eastern U.S. and western Europe tend to have colder winters."
Cohen and his co-authors began by asking themselves why winter temperatures in the northern hemisphere aren't going up as quickly as in the spring, summer and fall.
A look at weather and climate records showed that Arctic sea ice is forming later and disappearing earlier — and that the northern atmosphere is gradually getting warmer. At the same time, Siberia is getting heavier and heavier snowfalls.
Cohen theorized the two were linked, that more ice-free water and warmer air in the Arctic leads to more moisture in the northern atmosphere. In the cold temperatures of northern Eurasia, that moisture falls as snow.
Records show the Siberian snowpack has increased significantly over the last 25 years.
"In October, you start building up this cold dome of air," Cohen explained. "If you have a lot of snow, it reflects much of the sunlight back into space and cools the lower part of the atmosphere and you start to build cold, dense air. You get this dome of cold air that we associate with the Siberian High."
Previous studies have shown that snow in Siberia affects the strength of the Arctic Oscillation, which affects North America.
When that oscillation is strong, it creates powerful east-west winds that block cold polar air from drifting south. But when the oscillation is weak, more of that air starts moving north-south, pulling the Siberian High downwards.
"I like to think of Siberia as a refrigerator for the entire northern hemisphere," Cohen said.
"If you have less snow, it's like keeping the refrigerator door closed. The cold air stays locked up in the Arctic. But if the snow cover is much more expansive, it's like opening up the refrigerator door — the cold air spills out into the kitchen."
Cohen said his group's work explains why North American winter temperatures and Siberian snowfalls aren't doing what climate models predict they should.
"The model projections for the other three seasons turned out very good. The one season they're not doing so well is winter.
"I think there's a good explanation here."
That may be great for climate scientists. It's not so cheery for those enduring another season of discontent.
Cohen said the pattern of warm springs, summers and falls followed by cold winters is likely to persist — at least until climate change advances to the point where November precipitation in Siberia falls as rain, not snow.
Note to readers: This is a corrected story. A story originally moved on jan.12 said Judah Cohen works for the University of Massachusetts. He actually works for Atmospheric and Environmental Research, a weather research company.WINTER IN CANADA AND AROUND THE WORLD:
Michael Stilson of Windber, Pa., shovels wet-heavy snow along Graham Ave. in Windber, Somerset County, Monday, April 23, 2012.(AP)
JACKSON TOWNSHIP, PA
Snow blankets the trees and a road in Jackson Township, Pa., Monday, April 23, 2012. A spring nor'easter packing soaking rain and high winds churned up the Northeast Monday morning, unleashing a burst of winter and up to a foot of snow in higher elevations inland, closing some schools and sparking concerns of power outages. (AP Photo)
Two girls sit on sculptures amid the snow at Glenshee on April 4, 2012 in Glenshee, Scotland. (Jeff J Mitchell/Getty Images)
A rainbow appears as water splashes a local walking on the Sebastopol sea-front on March 3, 2012. (GENYA SAVILOV/AFP/Getty Images)
Palestinians walk during a snow storm in the West Bank city of Hebron as wintry weather swept through the region on March 2, 2012. (MENAHEM KAHANA/AFP/Getty Images)
Palle-Jooseppi, a male brown bear of Ranua Zoo, begins to wake up after winter hibernation in Ranua on February 23, 2012. (KAISA SIREN/AFP/Getty Images)
Rushing Dasher ridden by Natalie Friberg (c) leads the field in to the second turn during the Grand Prix Prestige race at the White Turf horse racing meeting held on the frozen Lake St Moritz on February 19, 2012 in St Moritz, Switzerland. (Photo by Alex Livesey/Getty Images)
Golfers practice at the driving range Wednesday, Feb. 22, 2012 in Concord, N.H. The range opened early this year because of a mild winter. (AP Photo/Jim Cole)
A man races his six-dog sled during the winter carnival on Jan. 28. (photo THE CANADIAN PRESS/Jacques Boissinot)
Sea smoke hugs the Kitimat, BC, harbour on Jan 19, 2012, surrounding the tug Smit Cecil and obscuring an empty barge anchored off the dock. Warmer fresh water from the Kitimat River is caught between the ocean water in the harbour and the frigid air, creating the sea smoke which is then caught by the wind. Kitimat was experiencing -23 C air temperature on this day, a windchill of -38 as arctic air kept much of Canada in the first deep freeze of the winter. (The Canadian Press Images/Robin Rowland)
Patrick O'Hara enjoys a walk through Springbank Park in London's west end with his daughter Quinn and grandson Aidan. (photo: The Canadian Press Images/Mark Spowart)
David Ferguson attempts to stay warm on his walk home from work -27C weather (with the wind chill it felt like -40C) in Saskatoon, Wednesday, January 18, 2012. (THE CANADIAN PRESS/Liam Richards)
Lucy Venegas, a soccer referee from Mexico in the city for the CONCACAF women's Olympic qualifying tournament, catches snowflakes in her mouth in downtown Vancouver, B.C., on Wednesday January 18, 2012. Cold weather has enveloped the lower mainland with Vancouverites dealing with temperatures 10 degrees below normal. (THE CANADIAN PRESS/Darryl Dyck)
A cyclist is framed by icicles hanging from Christmas lights on a tree in Vancouver, B.C., on Wednesday January 18, 2012. Cold weather has enveloped the lower mainland with Vancouverites dealing with temperatures 10 degrees below normal. (THE CANADIAN PRESS/Darryl Dyck)
A horse-drawn carriage makes its way down a street in Old Montreal during snowfall Thursday, Jan. 12, 2012. CANADIAN PRESS/Paul Chiasson.
Pedestrians brave the blustery winter weather as a storm system hits Ottawa on Thursday, Jan. 12, 2012. THE CANADIAN PRESS/Sean Kilpatrick.
Joe Graham works to clear snow from the front of his family's business in Dubuque, Iowa, Thursday, Jan. 12, 2012. AP PHOTO.
A motorist clears snow from their vehicle in Halifax on Wednesday, Nov. 23, 2011. A blast of wintry weather descended on the Maritimes causing numerous accidents, closing schools and delaying flights.THE CANADIAN PRESS/Andrew Vaughan
Karen Kelly shovels a walkway as snow removal crews clean up on Parliament Hill in Ottawa on Wednesday, November 23, 2011, after the first snowfall of the season brought upwards of 10 cm of snow to the nation's capital. (THE CANADIAN PRESS/Sean Kilpatrick)
A woman cleans snow from her car in Montreal, Wednesday, November 23, 2011 as the first heavy snowfall of winter hits Montreal and surrounding areas. THE CANADIAN PRESS/Graham Hughes
Minister of Justice Rob Nicholson makes his way along Wellington Street during a snowfall in Ottawa on Wednesday, November 23, 2011. The first snowfall of the season brought upwards of 10 cm of snow to the Nations capital. (THE CANADIAN PRESS/Sean Kilpatrick)
Beijingers walk through the first snowfall of the year at a section of the rebuilt city wall in Beijing on December 2, 2011. (MARK RALSTON/AFP/Getty Images)
Shoppers walk past large piles of snow in Samara's Leningradskaya Street on November 10, 2011 in Samara, Russia. Samara is one of thirteen proposed host cities as Russia prepares to host the 2018 FIFA World Cup. (Photo by Harry Engels/Getty Images)
A horse stands in the intense wind and snow Monday, Dec., 5, 2011 near his corral off of Highway 70 in Las Cruces, N.M. Snowfall started to blanket the City of the Crosses at about 11 a.m. and steadily continued throughout the day. (AP Photo/Las Cruces Sun-News, Shari V. Hill)
Traffic backs up behind snow plows clearing a street in Denver on Thursday, Dec. 1, 2011. As much as seven inches of snow is in the forecast for the Mile High City on Thursday. (AP Photo/Ed Andrieski)
Ruth Chauff, of New Orleans, laughs after making a small snowman near Point Park on Tuesday, Nov. 29, 2011., after snow fell across the Chattanooga, Tenn., area. She made a snowman with her daughter April Fontenot, not seen. (AP Photo/Chattanooga Times Free Press, Jake Daniels)
Snow covers Narikala, an ancient fortress dominating Tbilisi, the capital of Georgia on Monday, Nov. 28, 2011. (AP Photo/Shakh Aivazov)
Leaves and snow rest on the ground after a winter storm October 30, 2011 in Hartsville, Pennsylvania. Thousands in Pennsylvania and Delaware were left without power from the early winter storm that left up to 10 inches of snow in parts of the states. (Photo by William Thomas Cain/Getty Images)
SIGNAL MOUNTAIN, TENN.
An early snow covers tackling dummies at Signal Mountain High School football practice field, in Signal Mountain, Tenn., early Tuesday morning, Nov. 29, 2011. The snowfall is considered early for the region. (AP Photo/Chattanooga Times Free Press, Dan Henry)
Paul Worsowicz watches his putt during the traditional 29th annual Thanksgiving Day golf tournament Thursday, Nov. 24, 2011 in Concord, N.H. More than 100 players showed up at sunrise to play nine holes in the snow covered course.(AP Photo/Jim Cole)
EAST MONTPELIER, VT.
A flock of wild turkeys walk through a snow-covered field Wednesday, Nov. 23, 2011 in East Montpelier, Vt. Snow mixed with sleet and freezing rain is knocking out power to thousands of Vermonters and making the morning commute a slippery one.(AP Photo/Toby Talbot)