Possible explanation for the cold in US, Europe

[stormguy80]

This is interesting http://radioboston.wbur.org/2011/01/13/global-warming-snowfall

Don't know if I agree but its one climatologists theory of why its been cold - He's blaming it on increased fall snowfall in Siberia due to global warming.

[buckeye]

geezus, are people still talking about global warming?

[donsutherland1]

This is interesting http://radioboston.w...arming-snowfall

Don't know if I agree but its one climatologists theory of why its been cold - He's blaming it on increased fall snowfall in Siberia due to global warming.

Although I believe that there is an anthropogenic contribution to the observed warming over recent decades, unless the climatologist provides credible evidence that can separate the long-term climatic change from known synoptic patterns that contribute to such an outcome, his statement on a climatic contribution is little more than a hypothesis. The reality is that the AO- regime has again been the dominant driver of the synoptic pattern so far this winter. That increased snowfall in Siberia likely has an impact on the winter AO is one thing. But the climatologist needs to provide evidence that it is climate change that is mainly responsible for the increased Siberian snowfall and that such a contribution to the Siberian snowfall has also made the difference in the severe blocking that has predominated to date.

Going back to the point of the AO's influence, during the December 1, 2010-January 11, 2011 (last date re-analysis data is available) period, the AO has averaged -2.63. The following are comparisons between the composite 500 mb and surface temperature anomalies that have occurred when the AO has averaged between -3 and -2 during the December 1-January 11 timeframe (1950-2010) and the 500 mb and temperature anomalies during the December 1, 2010-January 11, 2011 timeframe:

Composite 500 mb Height Anomalies:

December 1, 2010-January 11, 2011 500 mb Height Anomalies:

Composite Temperature Anomalies:

December 1, 2010-January 11, 2011 Temperature Anomalies:

[BethesdaWX]

This whole thing is Chicken-egg. They go in tandom, but obviously we can thank the -AO for putting all this snowcover down in the first place.

[stellarfun]

Don, very nice analysis as usual.

Here is the original op-ed in the NY Times for Dr. Cohen's hypothesis.

http://www.nytimes.c...cohen.html?_r=1

And a series of Q&A of Dr. Cohen with respect to his hypothesis, and Dr. Cohen's links to articles on the hypothesis in peer-reviewed literature.

http://dotearth.blog...st/?ref=opinion

The NPR/WBUR link had a map of his DJF temperature prediction.

His JFM prediction as published in the NY Times below.

What I didn't find was any maps of the snow anomalies in Siberia, and it seems counter-intuitive that, if only from Coriolis forces, increased open water on the Siberian side of the Arctic would lead to more snow in Siberia.

[donsutherland1]

Thank you, Stellarfun.

I had previously read his op-ed, but didn't see the blog piece. I'll look up his papers at the MIT link. Many thanks for the links.

[nzucker]

The NPR/WBUR link had a map of his DJF temperature prediction.

His JFM prediction as published in the NY Times below.

What I didn't find was any maps of the snow anomalies in Siberia, and it seems counter-intuitive that, if only from Coriolis forces, increased open water on the Siberian side of the Arctic would lead to more snow in Siberia.

Looks as if he's predicting quite a cold January-March period here in the East with temperatures averaging around 1F below normal. I wonder if this is based on extrapolating the autumnal Siberian snow cover into a winter NAO/AO state. Does anyone know when this forecast was made? I would imagine the influence of fall snow cover is greatest in December and January, however, and then declines later in the winter.

It looks as if the NAO is starting to trend positive with the blocking shifting over to the Pacific side, so definitely a significant pattern change but still in line with thoughts about extreme high-latitude blocking dominating Winter 10-11. Just an amazing ridge right now over AK and the Bering Strait. Even with the La Niña continuing to strengthen as per NOAA SST anomaly maps, we're still locked into a blocky hemispheric pattern.

In all honesty, it's one of the coldest winters I can remember in the Hudson Valley/NYC metro.

[skierinvermont]

Looks as if he's predicting quite a cold January-March period here in the East with temperatures averaging around 1F below normal. I wonder if this is based on extrapolating the autumnal Siberian snow cover into a winter NAO/AO state. Does anyone know when this forecast was made? I would imagine the influence of fall snow cover is greatest in December and January, however, and then declines later in the winter.

It looks as if the NAO is starting to trend positive with the blocking shifting over to the Pacific side, so definitely a significant pattern change but still in line with thoughts about extreme high-latitude blocking dominating Winter 10-11. Just an amazing ridge right now over AK and the Bering Strait. Even with the La Niña continuing to strengthen as per NOAA SST anomaly maps, we're still locked into a blocky hemispheric pattern.

In all honesty, it's one of the coldest winters I can remember in the Hudson Valley/NYC metro.

I think his model is based on lots of other things besides fall snowcover.

[skierinvermont]

That increased snowfall in Siberia likely has an impact on the winter AO is one thing. But the climatologist needs to provide evidence that it is climate change that is mainly responsible for the increased Siberian snowfall and that such a contribution to the Siberian snowfall has also made the difference in the severe blocking that has predominated to date.

Excellent point, that's exactly what I said in the original NYT article on Cohen thread. The proposed mechanism is a multi-link chain and none of the links are very strong, so the connection from the first mechanism to the end result is probably nearly negligible.