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--- In californiadisasters@yahoogroups.com, Judith Citrin <jpcitrin@...> wrote:
>
> OP-ED CONTRIBUTOR, NEW YORK TIMES
> Bundle Up, It's Global Warming
> By JUDAH COHEN
> Published: December 25, 2010
> Lexington, Mass.
> Related in Opinion
>
> Dot Earth Blog: Putting a Siberian Snow Connection to the
> Test(December 28, 2010)
> THE earth continues to get warmer, yet it's feeling a lot colder
> outside. Over the past few weeks, subzero temperatures in Poland
> claimed 66 lives; snow arrived in Seattle well before the winter
> solstice, and fell heavily enough in Minneapolis to make the roof of
> the Metrodome collapse; and last week blizzards closed Europe's
> busiest airports in London and Frankfurt for days, stranding holiday
> travelers. The snow and record cold have invaded the Eastern United
> States, with more bad weather predicted.
>
> All of this cold was met with perfect comic timing by the release of a
> World Meteorological Organization report showing that 2010 will
> probably be among the three warmest years on record, and 2001 through
> 2010 the warmest decade on record.
>
> How can we reconcile this? The not-so-obvious short answer is that the
> overall warming of the atmosphere is actually creating cold-weather
> extremes. Last winter, too, was exceptionally snowy and cold across
> the Eastern United States and Eurasia, as were seven of the previous
> nine winters.
>
> For a more detailed explanation, we must turn our attention to the
> snow in Siberia.
>
> Annual cycles like El Niño/Southern Oscillation, solar variability and
> global ocean currents cannot account for recent winter cooling. And
> though it is well documented that the earth's frozen areas are in
> retreat, evidence of thinning Arctic sea ice does not explain why the
> world's major cities are having colder winters.
>
> But one phenomenon that may be significant is the way in which
> seasonal snow cover has continued to increase even as other frozen
> areas are shrinking. In the past two decades, snow cover has expanded
> across the high latitudes of the Northern Hemisphere, especially in
> Siberia, just north of a series of exceptionally high mountain ranges,
> including the Himalayas, the Tien Shan and the Altai.
>
> The high topography of Asia influences the atmosphere in profound
> ways. The jet stream, a river of fast-flowing air five to seven miles
> above sea level, bends around Asia's mountains in a wavelike pattern,
> much as water in a stream flows around a rock or boulder. The energy
> from these atmospheric waves, like the energy from a sound wave,
> propagates both horizontally and vertically.
>
> As global temperatures have warmed and as Arctic sea ice has melted
> over the past two and a half decades, more moisture has become
> available to fall as snow over the continents. So the snow cover
> across Siberia in the fall has steadily increased.
>
> The sun's energy reflects off the bright white snow and escapes back
> out to space. As a result, the temperature cools. When snow cover is
> more abundant in Siberia, it creates an unusually large dome of cold
> air next to the mountains, and this amplifies the standing waves in
> the atmosphere, just as a bigger rock in a stream increases the size
> of the waves of water flowing by.
>
> The increased wave energy in the air spreads both horizontally, around
> the Northern Hemisphere, and vertically, up into the stratosphere and
> down toward the earth's surface. In response, the jet stream, instead
> of flowing predominantly west to east as usual, meanders more north
> and south. In winter, this change in flow sends warm air north from
> the subtropical oceans into Alaska and Greenland, but it also pushes
> cold air south from the Arctic on the east side of the Rockies.
> Meanwhile, across Eurasia, cold air from Siberia spills south into
> East Asia and even southwestward into Europe.
>
> That is why the Eastern United States, Northern Europe and East Asia
> have experienced extraordinarily snowy and cold winters since the turn
> of this century. Most forecasts have failed to predict these colder
> winters, however, because the primary drivers in their models are the
> oceans, which have been warming even as winters have grown chillier.
> They have ignored the snow in Siberia.
>
> Last week, the British government asked its chief science adviser for
> an explanation. My advice to him is to look to the east.
>
> It's all a snow job by nature. The reality is, we're freezing not in
> spite of climate change but because of it.
>
>
> Judah Cohen is the director of seasonal forecasting at an atmospheric
> and environmental research firm.
>
------------------------------------
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