Climate change responsible for super-charging winter storms, scientists say

Suzanne Goldenberg in the Guardian (UK): Winters may be getting shorter, but watch out when it does snow: climate change is super-charging storms like the blizzard engulfing the American north-east, scientists said on Monday.

The heavier storms of recent years – snowfalls that shut down cities and brought heavy flooding to coastal areas of New England – carried the imprints of climate change, as researchers get better at detecting the fingerprints of global warming – even from snow.

It was too soon to pin the current storm to climate change, but a trend line was emerging, the scientists said. “The snow season is getting shorter,” said Kevin Trenberth, a climate scientist at the National Center for Atmospheric Research. “But the interesting thing is you can end up with heavier snows in part because of climate change.”

In general, climate change produces more extreme precipitation in North America – and if it’s cold enough, that produces snow. ... Nor’easters pack their punch from the contrast between cold land temperatures at the warmer Gulf stream and surrounding waters. Five of New York’s biggest snow storms have occurred since 2000, and 2014 was the hottest year in 130 years of temperatures records.

...“You can easily get as much as 20% more snow out of a storm than you would otherwise, as long as it is cold enough so that all of that moisture gets converted into snow. And that is usually the case in the wintertime,” Trenberth said....

NASA image of the current visitor to Carbon Based headquarters, January 27, 2015

Warm Pacific may paradoxically cause US winter freeze, says a study

Reuters: Unusually warm western Pacific waters linked to global warming may be the paradoxical cause of a bone-chilling winter in parts of the United States this year, a scientific study said on Thursday. The theory contrasts with other experts' views, including that the freeze was simply a freak natural event or that it was linked to a thawing of the Arctic in recent years that sent a blast of cold air south.

"People's reaction when they sit under 10 feet of snow is to say 'this cannot be man-made climate change'," said Professor Tim Palmer of Oxford University, who published his research in the journal Science. "But there is a plausible link," he told Reuters.

He said a strengthening of trade winds had led to a build-up of warm water in the western tropical Pacific, aggravated in recent years by global warming from man-made emissions of greenhouse gases. Thunderstorms linked to the warmth in turn disrupted the jetstream, high altitude winds which flow in vast meandering loops around the northern hemisphere, and sucked cold air from the Arctic. Detroit, for instance, suffered record snows and the coldest January since 1977.

Pinpointing the causes of the U.S. chill, when climate change should make cold winters less likely, would help companies, farmers, city planners or even home owners wondering if they should invest in extra roof insulation. Two other experts were unconvinced by Palmer's study.

Jennifer Francis of Rutgers University, who wrote in 2011 that a melting of Arctic ice may cause cold snaps, said the Pacific had a similar pattern of heavy rainfall in 2011-12 but the winter was mild in the United States....

A winter storm in New York City, MTA of the state of New York, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Warm North Atlantic Ocean promotes extreme winters in US and Europe

EurekAlert via the Institute of Physics: The extreme cold weather observed across Europe and the east coast of the US in recent winters could be partly down to natural, long-term variations in sea surface temperatures, according to a new study published today.

Researchers from the University of California Irvine have shown that a phenomenon known as the Atlantic Multidecadal Oscillation (AMO)—a natural pattern of variation in North Atlantic sea surface temperatures that switches between a positive and negative phase every 60-70 years—can affect an atmospheric circulation pattern, known as the North Atlantic Oscillation (NAO), that influences the temperature and precipitation over the Northern Hemisphere in winter.

When the AMO is in its positive phase and the sea surface temperatures are warmer, the study has shown that the main effect in winter is to promote the negative phase of the NAO which leads to "blocking" episodes over the North Atlantic sector, allowing cold weather systems to exist over the eastern US and Europe.

...To arrive at their results, the researchers combined observations from the past century with climate simulations of the atmospheric response to the AMO. According to their observations, sea surface temperatures in the Atlantic can be up to 1.5 °C warmer in the Gulf Stream region during the positive phase of the AMO compared to the negative, colder phase. The climate simulations suggest that these specific anomalies in sea surface temperatures can play a predominant role in promoting the change in the NAO.

Lead authors of the study Yannick Peings and Gudrun Magnusdottir said: "Our results indicate that the main effect of the positive AMO in winter is to promote the occurrence of the negative phase of the NAO. A negative NAO in winter usually goes hand-in-hand with cold weather in the eastern US and north-western Europe."...

Winter traffic in New Hampshire, shot by MarkBuckawicki, Wikimedia Commons,  under the Creative Commons CC0 1.0 Universal Public Domain Dedication

Massive storm system takes aim at winter-weary US Midwest, East

Reuters: A massive winter storm system packing cold air, snow and freezing rain was pummeling the central United States on Sunday and headed for the East Coast, sending temperatures plummeting and causing major delays for weekend travelers.

Rainfall and snow associated with the system will stretch over 1,500 miles, stretching from southeastern Colorado to southern Massachusetts, meteorologists said.

The storm "is going to be a real mess," said Bruce Sullivan, a senior meteorologist with the National Weather Service in Silver Spring, Maryland.

"The main system is injecting a lot of moisture and cold air out over the Southern Plains," he said. "It's going to bring quite a bit of precipitation." Up to 12 inches of snow could fall on an area from eastern Kansas to Pennsylvania before the system dissipates on Monday....

This snow man is in Finland, but you get the idea, shot by Petritap, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Big freeze and storms in the US impose losses up to $40 billion

Peter Morici in UPI: The January freeze and crippling storms gripping the eastern United States and upper Midwest are having significant effects on normal life and commerce. Gauging its ultimate impact on the U.S. economy -- still affected by a nagging hangover from the Great Recession -- is far more complex than merely adding up lost retail and insurance payouts for damage.

The United States braces for cold and storms each winter but this year's conditions are more severe than cities and counties customarily prepare to address. Many commercial structures and homes weren't built for these unanticipated conditions.

The storms these past few weeks in New York would have been manageable for Minneapolis but the Big Apple isn't set up for a Minnesota winter. Nor is Minnesota for arctic conditions. For a few days, many restaurants closed and workers didn't go to their offices. Overall retail sales were adversely affected, as many shoppers couldn't so easily get to the malls. Pipe bursts and similar mechanical breakdowns damaged homes and commercial structures.

Many businesses closed and lost worker productivity, even though many employees will still be paid. Overall ... the freezing temperatures and ice imposed big losses. Initially, lost economic activity and damages will range between $20 billion and $40 billion
.
Still, it is important to recognize, unlike the 1950s when the nation's workers were much more concentrated in factories, most of the lost productivity and commerce in a modern service economy is more easily made up once warmer weather returns....

An 1895 painting by John Henry Twachtman, "Snow"

Wretched winter grips Northeast; huge Pennsylvania Turnpike pileup

Michael Muskal and Richard Simon in the Los Angeles Tmes: Mother Nature had scant love for the eastern portion of the United States on Valentine’s Day, continuing a streak of miserable and deadly weather that has turned much of the nation into a snowy, icy mess and caused a major pileup on the Pennsylvania Turnpike.

On Friday, one side of the Pennsylvania Turnpike outside Philadelphia, an area that got more than a foot of snow, was blocked by collisions that caused minor injuries. At least 16 motorists were injured, including five trauma victims, in a series of crashes involving dozens of vehicles on the Pennsylvania Turnpike that began just after 8 a.m. Friday. Traffic along the turnpike was backed up for miles, the Associated Press reported.

As the South and Mid-Atlantic regions continued to dig out Friday, the storm, carrying heavy snows and gusty winds, moved through New England, according to the National Weather Service. Despite sunny skies in previously hard-hit regions, hundreds of thousands of people remained without electricity, mainly in the South, and more than 20 people have died, including a pregnant woman killed by a plow in Brooklyn. Her baby son was delivered by emergency cesarean section on Thursday.

Snow falls, already at record levels after a series of storms this season, continued to accumulate. More than 22 inches of snow was reported in Somerset County, Pa., and parts of upstate New York received more than two feet of snow.

The nation’s airline system was beginning to recover. More than 10,000 flights had been canceled in recent days since the storm came roaring out of the Southwest, through the Deep South and following the traditional track of a nor’easter up the East Coast. On Friday, cancellations dropped to about 1,100 from 6,500 on Thursday, according to Flightaware.com, a website that monitors the airline system....

"Snow in New York," a 1902 painting by Robert Henri

Weather swap: Is America’s ‘polar vortex’ linked to record warm winter in Russia?

Russia Today: As Americans kept struggling with extreme cold and snow brought on by a ‘polar vortex,’ people in central Russia were puzzled by warm rainy weather that swept all the snow away. Now weather experts say the two anomalies are in fact connected.

As residents of the US and Canada were surprised by the frigid cold dipping below minus 30 degrees Celsius, Russians were also surprised by the January weather, with temperatures in Moscow rising some 11 degrees above average and melting the snowy “New Year’s spirit” away.

Central Europe also experienced sudden warm-up, and trees in Moldovan capital Chisinau got confused to the point their buds started swelling, apparently in anticipation of the blooming season. One of the reasons for the snowless January in Russia and the coldest winter in the last 17 years for the US is in fact the shifting of the Arctic Cyclone towards North America, Greg Carbin, warning meteorologist for the National Oceanic and Atmospheric Administration, told Itar-Tass news agency.

The cyclone may come to Russia in a week or two, Carbin said, predicting that the temperatures in the country could soon leap back to below zero and even below average.

Russian meteorologists have said that the gradual return of winter is to be expected even sooner. According to the Hydrometeorological Centre of Russia, frost and snow is coming back, starting from this weekend and reaching minus 17 degrees Celsius on Wednesday night....

A 1919 snowstorm in New York City

Cold weather snap fuels misinformation over climate change

Peter Moskowitz in Al Jazeera America: Meteorologists predict record-low temperatures for large swaths of the United States on Sunday and Monday. The cold snap, which comes after snow blanketed much of the northeastern United States last week, has also led to confusion surrounding how weather relates to global warming.

Since the winter weather began, some Americans have taken to blogs, television stations and comment threads, asking (often rhetorically) how the weather can be so cold if the world is supposed to be getting warmer.

...But those who think cold weather disproves climate change may be ignoring a solid and ever-increasing body of evidence. Cold weather is just that -- weather, which is defined by NASA as “conditions of the atmosphere...over a short period of time.”

According to most climate scientists, no weather condition can be linked to climate change. Just as the cold snap can’t necessarily be linked to climate by itself, neither can the unprecedented heat wave currently hitting Australia. (It’s so hot, meteorologists have been forced to add new colors to their heat maps.)

...Scientists warn that as every country in the world starts to grapple with the effects of climate change, the current confusion surrounding the science could have dire consequences. As world leaders attempt to craft climate policy, experts say, it’s important everyone be on the same page, or else the confusion could cause gridlock, and humans could continue to warm the globe at record levels....

Finnish soldiers during the Winter War, 1939-1940, shot by Finnish Army personnel

After bad year, insurers face potential ice-storm hit

Tim Kiladze in the Globe and Mail (Toronto): Canadian insurers are grappling with the prospect of financial damage from yet another severe storm, capping off a brutal year that raised serious questions about how the industry will deal with the costs of climate change.

After suffering a $3-billion hit from natural disasters such as the summer floods in Alberta and the Greater Toronto Area, property and casualty insurers are now racking up claims from the ice storm that hit Ontario, Quebec and Atlantic Canada. It is still too early to determine the costs, but insurers are bracing for a bruising.

 “The ice storm that hit Central Canada this weekend has caused significant physical damage and emotional trauma for many households, and will likely be a significant insured event for the industry,” André-Philippe Hardy, a financial services analyst at RBC Dominion Securities, wrote in a note to clients. Insurer RSA Canada said the storm was “one of the worst we’ve seen in Toronto in quite some time.”

Insurers aren’t the only ones on the hook – they share the burden with reinsurance companies that take on a portion of the risk – but the latest storm reopens a deep wound. The property insurance industry is coming to grips with evidence that severe weather events are becoming more frequent. That has potentially significant implications for consumers and businesses, who may be forced to pay higher premiums as insurers try to recover from the losses.

“As severe weather events become more extreme and frequent, we will continue to pursue our efforts to ensure that the protection we offer reflects our country’s new climate reality and that governments, consumers, businesses and all stakeholders pursue their efforts to better adapt to climate change,” Charles Brindamour, chief executive officer of insurer Intact Financial Corp., said in November after the company reported its first underwriting loss in a decade....

Generic NOAA image of ice storm damage

US Plains young wheat crop at risk from arctic blast

Reuters: Bitter cold conditions expected to move through the U.S. Plains wheat belt next week will put the young crop at risk of winterkill if the region does not see snow before then, an agricultural meteorologist said on Friday.

World Weather Inc meteorologist Drew Lerner said a Canadian cold front is heading to the Plains wheat country, Kansas to Colorado, mid- to late next week. Temperatures could dip to below zero Fahrenheit (-18 C) by next Friday.

But the chances of the region getting snow before then are good, Lerner said. The snow provides a layer of insulation to the crop, protecting it from damage. The U.S. weather model is forecasting heavy snows for the Plains and western Midwest next week.

...Over the next few days, the Plains winter wheat belt will warm up into the range of 50 to 60s degrees F, bringing some of the crop out of dormancy in the southern portion of the belt, he said. The crop will benefit from the moisture and the transition to colder temperatures late next week should be gradual, easing crop stress brought on by the frigid temperatures....

Claude Monet's 1891 painting of stacks of wheat in the snow at sunset

Winter Storm Boreas update: At least 13 deaths as ice, snow create dangerous travel in Plains, South

The Weather Channel: Winter Storm Boreas, already blamed for at least thirteen deaths, is a massive storm that will impact the nation from coast to coast with rain, snow, sleet, and ice during the busiest travel week of the year. It's bringing a mix of snow, sleet and freezing rain to parts of Arkansas, Oklahoma and Texas on Monday then will trudge east this Thanksgiving week.

"Before this is over, Winter Storm Boreas will have impacted 100 million people," said The Weather Channel's winter weather expert Tom Niziol.

The National Weather Service said late Sunday night that a winter storm warning for most of North Texas had been replaced with a winter weather advisory through noon Monday. A mix of rain, light freezing rain and light sleet was expected, but meteorologist Steve Fano with the weather service's Dallas-Fort Worth office said the temperatures would not be as cold as initially forecast.

"I'm concerned about the area in Arkansas and through Memphis this afternoon, especially Little Rock," said Niziol. "We could get as much as a quarter inch of ice there today."

The storm dropped more than 10 inches of snow on parts of southwest Oklahoma overnight, and a winter weather advisory remained in place for much of the southeast of the state with freezing rain and sleet in the cards....

Wilson Bentley shot this 1902 photo of a snowflake

Scientists uncover the secret life of frozen soils

Notice of a publication from the Agricultural Institute of Canada:  Contrary to popular belief, winter plays a significant role in farming. The ground beneath that seemingly peaceful blanket of snow is not idle during the long, cold winter months and researchers want to know what is going on.  Historically, studies have focused on times of the year when data can be easily gathered. However, winter’s freeze-thaw cycles, nutrient run-off and the effect of snow cover - or lack of snow cover - on soil are of great concern and can have significant impacts.

Inspired by a session at the 2011 joint Canadian Soil Science Society Meeting conference, the September issue of the Canadian Journal of Soil Science is a special issue on biological, physical and chemical processes in seasonally frozen soils. This comprehensive collection of papers tackles the frosty subject of frozen soils in Canada’s varying topography and geographically distinct regions.

“Although some of these processes have been investigated in soils that are frozen for most of the year, such as in the Arctic, Antarctic and at high elevations, they have received less attention in seasonally frozen soils,” explains Dr. Barbara Cade-Menun, lead author of one of the papers and guest editor of this issue of the Canadian Journal of Soil Science.  “This may in part be due to the challenges of conducting field and laboratory research under winter conditions – it is much easier to wait until spring for sample collection.”

“Yet this important research could impact producers’ decisions during the growing and harvest seasons. A thorough knowledge of the effects of winter and freeze–thaw on soil winter processes in seasonally frozen soils is essential for their proper management, now and in the future. The papers in this special issue add to our knowledge in this area, could lead to future improvements in farming productivity and also suggest important future research directions.”...

A frozen field, shot by Philip Halling, Wikimedia Commons via Geograph UK, under the Creative Commons Attribution-Share Alike 2.0 Generic license

Winter to hang on in US Northeast

Terra Daily via UPI: The U.S. Northeast is likely to experience six more weeks of winter weather lasting into March, long-range forecasters at AccuWeather.com say.

The Northwest is also likely to have winter maintain its grip on the region, regardless of what Punxsutawney Phil has to say on Groundhog Day, forecasters said.

A couple of winter storms may impact the Northeast in February and March, they said. "I think we could still see some late-season winter storms [in the Northeast]," AccuWeather lead long-range forecaster Paul Pastelok said.

Snow along the Interstate 95 corridor from Washington to New York City and Boston is not unusual, he said; "Typically, February to March is the season on the East Coast."...

The south end of Boston covered in snow, in 2008, shot by Ben Becker, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Why Russia's cold snap is so deadly

Mark Lallanilla in Live Science: If any nation on Earth is accustomed to dealing with a harsh winter, it would be Russia. But from the farthest reaches of Siberia to downtown Moscow, the Russian people are being pummeled by a winter so brutal it's shattering cold-weather records across the continent — and it's only December.

As temperatures plunge as low as –minus 58 degrees Fahrenheit (minus 50 degrees Celsius) in some areas, the Pravda news site reports that 45 people have died of causes related to the subfreezing weather; 21 people froze to death in just one day. Hundreds more have been hospitalized with frostbite and other conditions.

Subfreezing weather combined with heavy snowfall in some regions have crippled the nation's infrastructure, closing roads, scrambling airline flights and bursting pipes that carry water and heat into homes, schools and businesses, according to RT.com.

This winter is the coldest on record since 1938, reports RT.com. The freakish cold spell, which has already lasted five days, is expected to continue through the weekend....

Russian winter, near Moscow, shot by Aleks G, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Snowy winter ahead for Rockies and Northeastern US, Accuweather says

Reuters: Snow lovers living in the U.S. Northeast and Rocky Mountains are going to love this coming winter, according to AccuWeather.com. The private weather forecasting firm released its long-range winter forecast on Wednesday, highlighting its predictions for temperature and precipitation trends.

While much of the northern part of the country, stretching from Wisconsin to eastern Washington, will see below-normal snowfall, Accuweather.com said the coming winter will be marked by plenty of big storms in the Northeast and mid-Atlantic. The firm's meteorologists are also predicting an early start to the winter season, with above-normal snowfall and below-normal temperatures, in the central and southern Rockies.

Temperatures in the Northeast may start out slightly warmer than normal, the forecasting firm said, but would drop as the season progresses and snow accumulates. In the Midwest, where the worst drought in 50 years hurt crops this year, Accuweather.com said snowfall levels would fall short of normal levels again this winter.

Temperatures may start out slightly above to near normal in the region, but as the season progresses and some snow accumulates, it will turn colder than normal by February. The Gulf Coast and Southeast meanwhile are expected to have a wet winter, with above-normal precipitation, Accuweather.com said, bringing some relief to the parched Southern Plains and Texas....

Minnesota in December of 2010, shot by Michael Hicks, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Mild winters are detrimental to butterflies

William G. Gilroy in the Notre Dame News: The recent mild winter throughout much of the United States was a cause for celebration for many. However, butterfly aficionados shouldn’t be joining in the celebration. A new study by Jessica Hellmann, associate professor of biological sciences at the University of Notre Dame, and researchers from Western University found that mild winters, such as the one many of us just experienced, can be taxing for some butterfly or possibly other species.

Hellmann and her fellow researchers studied caterpillars of the Propertius Duskywing butterfly, which feed on Gary Oak trees. This species of caterpillar, like many insects, has a higher metabolic rate and burns more fat during mild winters.

“The energy reserves the caterpillars collect in the summer need to provide enough energy for both overwintering and metamorphosing into a butterfly in the spring,” Caroline William, lead author of the study, said.

So a butterfly needs to conserve as much energy as it can during the winter months. In the paper, Hellmann and her colleagues explain for the first time how warmer winters can lead to a decrease in the number of butterflies.

However, Hellmann and the Western University researchers found that warmer winters might not always reduce butterfly populations as much as one might initially think. They reared caterpillars in two different locations: one which often experiences more variable and warmer winter temperatures and one which generally features more stable and generally cooler winter temperatures. The caterpillars that were exposed to the warmer and more variable conditions were better able to withstand the warmer conditions, simply by being exposed to them. They did so by lowering the sensitivity of their metabolism....

Dreamy Duskywing (Erynnis icelus), Ottawa, Ontario, shot by D. Gordon E. Robertson, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Mid-Atlantic suburbs can expect an early spring thanks to the heat of the big city

University of Maryland Center for Environmental Science: If you’ve been thinking our world is more green than frozen these days, you’re right. A recent study has found that spring is indeed arriving earlier – and autumn later – in the suburbs of Baltimore and Washington, D.C. The reason? The urban landscape traps heat in the summer and holds it throughout the winter, triggering leaves to turn green earlier in the spring and to stay green later into autumn. The result is a new, extended growing season.

Scientists used high-resolution satellite data collected over the past 25 years to look at the number days that trees have green leaves in the forests of the Mid-Atlantic. The study found that urban heat islands affected the growing season in areas within 20 miles of the city. As a result, gardeners may have more time to grow their vegetables and plant new varieties.

"This study provides important insight not only into the length of the growing season, but also into changes in water balance and carbon storage that will be accompanying climate change," said Dr. Don Boesch, president of the University of Marlyand Center for Environmental Science.

...“Everything changes when the leaves turn green,” said the study’s lead author Dr. Andrew Elmore of the University of Maryland Center for Environmental Science's Appalachian Laboratory. “Trees start pumping water into the atmosphere. They take carbon dioxide out of the atmosphere. They make sugars and build plant tissue. It’s as if the entire landscape goes from exhaling to inhaling.”

The study also pinpointed other factors that influence the timing of spring and autumn in areas outside the influence of urban heat islands, including the elevation of the landscape, proximity to tidal water, and cold air drainage in small valleys...

Map of growing season length from the University of Maryland website

215 Russians die in cold snap; well over 600 in Europe

Terra Daily via AFP: Some 215 Russians have died this year in a prolonged period of abnormally cold winter weather, the health ministry said Monday as the overall death toll for Europe rose to well over 600. Heavy snow continued to fall on Monday in Romania and Bulgaria, but the cold snap that froze much of Europe for the past two weeks began to ease in the west of the continent.

In Russia, 215 people died and 5,546 people suffered from hypothermia and frostbite, including 154 children, between January 1 and February 13, the ministry said in a statement. While accustomed to frosty winters, Russia has seen 20 days of unusually cold weather, with the average temperature falling 7 to 14 degrees Celsius below average, the state weather service said.

In Moscow, the temperature was minus 20 degrees Celsius (minus four Fahrenheit) on Monday afternoon, the state weather service said. While Russian apartment blocks are generally well heated, the homeless are particularly at risk....

A Moscow winter in 2007, shot by Andrey, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Blizzards push southeastern Europe energy grids to limits

Oleg Vukmanovic and Maja Zuvela in Reuters: Blizzards and ice-laden power lines in southeastern Europe pushed gas and electricity networks near to breaking point Wednesday as consumption soared, while some western countries scrambled to prevent similar breakdowns.

As electricity cables buckled under the weight of ice and snow in southeastern Bosnia, where some 15,000 customers were left in darkness, Serbia warned of a "possible collapse" of its energy system as record-breaking demand stretched the power grid near its technical limits.

Serbia's government adviser for energy issues, Petar Skundric, said the Balkan nation should reduce power consumption by 10 percent "to avoid problems and possible collapse of the energy system."

"In only a week's time Serbia has broken six historical records both in consumption and production of electricity," Skundric told reporters. "The system is operating at the very border of its technical capabilities, and we should do our best to reduce both consumption by at least 10 percent from the current level and production by around some 500 MW," he said....

A snowflake, shot by NOAA

Global warming set to bring colder, snowier winters

Kate Ravilious in Environmental Research Web: The world is getting warmer, which should mean warmer winters - right? Wrong - a new study shows that global warming produces colder winters and heavier dumps of snow for large swathes of the northern hemisphere.

In Canada it was dubbed 'Snowmageddon', while the Brits called it 'The Big Freeze'. Across Europe and the eastern United States temperatures plummeted for weeks on end during the winter of 2009/2010 and heavy snowfall caused major disruption. And then it happened all over again during the winter of 2010/2011, causing many to question whether global warming was happening at all. Now research suggests that colder winters have become more frequent over the past two decades, and were likely a product of global warming.

Judah Cohen, from Atmospheric and Environmental Research (AER) in Massachusetts, US, and his colleagues studied northern hemisphere temperature, humidity, snow cover, and sea ice cover data from the last twenty years. They show that as northern hemisphere summer temperatures have risen, September sea ice cover on the Arctic Ocean has shrunk. At the same time atmospheric moisture levels in the Arctic have risen, October snowfall across Europe has increased, and winters have become colder (Environmental Research Letters).

...The new data suggests that the probability of a negative Arctic Oscillation establishing has been increasing since the 1980s, and Cohen sees no reason why increasing autumn snow cover will cease to favour a negative winter Arctic Oscillation in the coming decades. However, if summer and autumn temperatures continue to rise then the extra atmospheric moisture may fall as autumn rain, rather than snow.....

Nicknamed “snowpocalypse” and “snowmageddon,” an exceptionally severe winter storm dropped several feet of snow around the Washington, D.C., area in early February 2010. Crashed and abandoned cars littered roads as airlines canceled hundreds of flights. Even the DC Metro train system stopped functioning in places. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this true-color image on February 7, 2010, showing part of the region affected by heavy snowfall. Snow blankets the area hundreds of kilometers inland from the Atlantic coastline. Along the latitude of New York City, however, snow cover thins considerably.