Extreme winter weather linked to climate change

WASHINGTON Tue Mar 1, 2011 5:29pm EST

Pedestrians walk on the streets of Chicago after a major snowstorm February 2, 2011. REUTERS/John Gress

Pedestrians walk on the streets of Chicago after a major snowstorm February 2, 2011.

Credit: Reuters/John Gress

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WASHINGTON (Reuters) - This winter's heavy snowfalls and other extreme storms could well be related to increased moisture in the air due to global climate change, a panel of scientists said on Tuesday.

This extra moisture is likely to bring on extraordinary flooding with the onset of spring in the Northern Hemisphere, as deep snowpack melts and expected heavy rains add to seasonal run-off, the scientists said in a telephone briefing.

As the planet warms up, more water from the oceans is evaporated into the atmosphere, said Todd Sanford, a climate scientist at the Union of Concerned Scientists. At the same time, because the atmosphere is warmer, it can hold onto more of the moisture that it takes in.

Intense storms are often the result when the atmosphere reaches its saturation point, Sanford said.

This year, a series of heavy storms over the U.S. Midwest to the Northeast have dropped up to 400 percent of average snows in some locations, said Jeff Masters, director of meteorology at Weather Underground.

The amount of water in that snowpack is among the highest on record, Masters said.

"If you were to take all that water and melt it, it would come out to more than 6 inches over large swaths of the area," Masters said. "If all that water gets unleashed in a hurry, in a sudden warming, and some heavy rains in the area, we could be looking at record flooding along the Upper Mississippi River and the Red River in North Dakota."

That tallies with projections by the U.S. National Weather Service, which last month said a large stretch of the north central United States is at risk of moderate to major flooding this spring.

SPRING CREEP

Spring floods could be exacerbated by spring creep, a phenomenon where spring begins earlier than previously.

"We've documented in the mountains of the U.S. West that the spring runoff pulse now comes between one and three weeks earlier than it used to 60 years ago," Masters said. "And that's because of warmer temperatures tending to melt that snowpack earlier and earlier."

In the last century, global average temperatures have risen by 1.4 degrees Fahrenheit (.8 Celsius). Last year tied for the warmest in the modern record. One place this warmth showed up was in the Arctic, which is a major weather-maker for the Northern Hemisphere, according to Mark Serreze, director of the U.S. National Snow and Ice Data Center.

One driver of this winter's "crazy weather," Serreze said, is an atmospheric pattern known as the Arctic Oscillation, which has moved into what climate scientists call a negative phase.

This phase means there is high pressure over the Arctic and low pressure at mid-latitudes, which makes the Arctic zone relatively warm, but spills cold Arctic air southward to places like the U.S. Midwest and Northeast.

This negative Arctic Oscillation has been evident for two years in a row, the same two winters that have had extreme storms and heavy snowfalls.

It is possible, but not certain, that the negative Arctic Oscillation is linked to warming of the Arctic, which is in turn influenced by a decrease in sea ice cover throughout the region.

The only underlying explanation for these events is climate warming due to heightened greenhouse gas levels, Serreze said.

(Editing by Mohammad Zargham)

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Comments (4)
bsbailey wrote:
It had to happen – someone is actually trying to link the recent harsh winter to man-made global warming. When will people realize that the Earth and its weather will do as it pleases regardless of human activity – as it has done since long before we existed and as it will continue to do long after we’re gone. It is the height of human arrogance to believe that we can “limit” or “reverse” global warming. The planet was warmer in the Dark Ages before fossile fuels were discovered. Then it went through a “Little Ice Age” for about 500 years causing catastrophic crop failure and famine. The planet was hotter 120,000 years ago at the peak of the last interglacial period, before sliding into the last major ice age (which officially ended about 9000 years ago). We are climbing into the current interglacial period. We do have some influence, I agree, but it is tiny compared to the geologic time scale and the natural changes in climate. The sun and Earth’s orbit have much more impact – and we can’t control that.

Mar 01, 2011 7:08pm EST  --  Report as abuse
Randy549 wrote:
I bought everything up to the very last sentence in the article, which should have read: The best explanation for these events is climate warming.

There is evidence that the earth’s climate is warming, as that can be directly measured. (Though, some of the measurement techniques have been challenged, for example placing measurement devices on top of tall buildings in the middle of large urban areas and then neglecting to compensate for increased warming as the urban area grows in size over time.)

There is evidence that the amount of CO2 in the atmosphere has increased, as that can be directly measured.

The two sets of measurements correlate fairly well with each other. But as any scientist knows, that does not prove, by itself, that one is causing the other.

It is further proposed that the reason for the increased CO2 in the atmosphere is solely due to activities by humans rather than natural processes, and therefore humans have the power to reverse it. The conviction that some have for this theory equals or exceeds the depth of feelings that others have about their religious faith.

In the last sentence, Mr. Serreze appears to be expounding his religious faith, since he does not even mention in passing the evidence he has for that statement. Oh..I know, it must be in the Book of AlGore.

Mar 01, 2011 7:44pm EST  --  Report as abuse
SheInBOS wrote:
I agree with the two previous commentators here. This article cites CO2 as causing global warming like it is a dogma. In fact, this dogma has a very poor evidentiary record. Weather has varied, along with extreme events since forever. The NAO negative phase that the article mentions cannot be related to CO2, since it has happen cyclically for thousands (millions?) of years.

Furthermore, if you think global warming is bad, then try global cooling.

Mar 01, 2011 8:25pm EST  --  Report as abuse
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