Guest Post by Willis Eschenbach
I wrote a post called I Used To Be Snow White (… but then I drifted) a week or so ago about a study titled “Impact of Declining Arctic Sea Ice on Winter Snowfall” (PDF) that claimed to link low arctic ice levels with high snow levels. To recap, their specific claims were:
Abstract
While the Arctic region has been warming strongly in recent decades, anomalously large snowfall in recent winters has affected large parts of North America, Europe, and East Asia. Here we demonstrate that the decrease in autumn Arctic sea ice area is linked to changes in the winter Northern Hemisphere atmospheric circulation that have some resemblance to the negative phase of the winter Arctic Oscillation. However, the atmospheric circulation change linked to the reduction of sea ice shows much broader meridional meanders in mid-latitudes and clearly different interannual variability than the classical Arctic Oscillation. This circulation change results in more frequent episodes of blocking patterns that lead to increased cold surges over large parts of northern continents. Moreover, the increase in atmospheric water vapor content in the Arctic region during late autumn and winter driven locally by the reduction of sea ice provides enhanced moisture sources, supporting increased heavy snowfall in Europe during early winter, and the northeastern and mid-west United States during winter. We conclude that the recent decline of Arctic sea ice has played a critical role in recent cold and snowy winters.
I showed that if there is such an effect, it is not visible using the snow data for the whole US. I thought this would settle it. But folks said, and fairly, that I wasn’t really dealing with their claim. They said I needed to deal with a) the regional nature of their claim, involving northeastern US and Europe, and b) the temporal nature of the claim, comparing only winter snowfall to autumn sea ice. So I decided to take a look at the winter snow data for the northeastern US compared to autumn sea ice.
Unfortunately, I couldn’t find area-wide data for the northeastern US, but I did find something better. This is one of the longest continuous records of snowfall in the northeastern US—the century and a half long record of the snowfall in Central Park in New York City.
Figure 1. Winter snowfall (December/January/February) for Central Park, New York. There is a slight but not statistically significant decrease in winter snowfall over the last century and a half.
So … how well does this correlate with the arctic ice levels? Well, not to put too fine a point on it … no better than my first look at the question.
Here’s the comparison of the snow and ice. I have standardized both of them so that we can compare them directly.
Figure 2. Central Park winter snow (December/January/February) versus Arctic autumn ice (September/October/November). Data have been standardized to allow a direct comparison
As you can see, there is little correlation, and the numbers bear that out. There is a weak statistical relationship (r^2 = 0.13) which is not significant at the p<0.05 level.
I thought that because there is no trend in the snowfall data, perhaps I might get better significance if I detrended the ice data. This would highlight the year by year variations that are theoretically responsible for the year-by-year variations in snowfall. Figure 3 shows that relationship, with the ice data inverted to better illustrate the relationship.
Figure 3. Central Park winter (DJF) snow totals versus inverted, detrended Arctic autumn (SON) ice levels.
Now, this is a very interesting figure, because it illustrates the way that our eyes find patterns when none are there. At first glance, this looks like it is a pretty good relationship. But in fact, that is an illusion. The mathematical analysis says that the r^2 is even worse, only 0.02, and like the previous graph, it is also not statistically significant, in fact the significance is worse (p ≈ 0.4).
Upon closer examination, we can see why that is so. For example, from about 1990 to 1995 when ice decreased, snow generally increased … but not proportionally. When the ice was extremely low there was a little more snow, and when the ice was only a little low, there was a lot more snow. For there to be a relationship, it needs to be proportional. Also, although in general the snow seems to change with the ice, in fact on a year by year basis, there are huge excursions. Look at 2011, for example, very low ice, but in contradiction to their claim, there’s also very low snow.
So I have found the same thing on a regional level using their autumn ice/winter snow claim, that I found when I looked at the data for the entire US for the full year. If there is any association between winter snowfall in the northeastern US and the autumn ice levels, it is very, very weak. There certainly is no sign of it in the Central Park records.
All the best,
w.
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The Figure 2 shows (superficially) that decreasing sea ice destabilizes winter snow towards more extreme variations. Which is at least logically consistent with the often-heard argument that one effects of a warmer world is a higher pole-equator temperature gradient, which causes more extreme weather events.
So simple correlations don’t seem to show any relationship. Perhaps the next step is to examine the correlations between the derivatives.
My first thought when I first read in some paper that there was more snowfall and cold because there was less arctic ice, was that it must have been really warm in the LIA. There was much more Arctic ice then. Or doesn’t it work in reverse?
Hi Willis, from your Gualala neighbor,
Almost a year ago “Climate Audit” linked to a news report from 1958 explaining how an ice-free Arctic (or at least a low ice-cover Arctic) provided humidity that fueled the snow machine resulting in the build up of the huge ice cap over North America during the past ice age. The cause: intrusion of tepid Atlantic water into the Arctic. The cause of the end of the Ice Age: falling sea level eventually stopped the intrusion of Atlantic waters into the Arctic.
http://strongasanoxandnearlyassmart.blogspot.com/2011/07/scientists-predict-another-ice-age-is.html
The jet stream changes and things change too…
John A. Fleming says, March 12, 2012 at 4:15 pm:
The Figure 2 shows (superficially) that decreasing sea ice destabilizes winter snow towards more extreme variations. Which is at least logically consistent with the often-heard argument that one effects of a warmer world is a higher pole-equator temperature gradient, which causes more extreme weather events.
Of course, there’s the oft-heard argument that global warming will cause greater polar region warming, decreasing the pole-equator temperature gradient.
Is there anything global warming can’t do, simultaneously and contradictorily, when there’s gov’t megabucks at stake?
On the NSIDC site they say Air temperatures over the Laptev, Kara and Barents seas ranged from 4 to 8 degrees Celsius (7 to 14 degrees Fahrenheit). That should be 39.2 F to 46.4 ºF or converting it the over way -13.8 C to -10 c.
Confused ? I am.
http://nsidc.org/arcticseaicenews/
Can’t be doing with this font Anthony. It is sending me boz eyed.
John A. Fleming says:
March 12, 2012 at 4:15 pm
Thanks, John. The “destabilization” is an artifact of the shortness of the Figure 2 record. If you look at Figure 1, you’ll see that the recent record is in no way historically unusual or “destabilized”. Indeed, there is no record anywhere of “more extreme weather events”, that’s an AGW urban legend.
This to me is one of the huge problems with the original study. They used only a few years of data … not good.
w.
Without looking at the paper, the hypothesis seems to be that the lack of ice in the arctic should have a similar effect that the lack of ice does on lake effect snow down wind of the Great Lakes. Once the lakes freeze over the snow decreases in the area, so a longer season of open water means more snow in the Tug hill plateau for example. The only thing is that where the effect would be is downwind of open water. Central Park doesn’t seem to be a good test spot.
Always a great read Willis. If I had to hazard a guess, you could take almost any single weather station and show the correlation between lower Arctic ice and greater local snowfall to be false. But when you throw all the weather station data into a big pot and average them out using Singular Value Decomposition a distinct and scientifically arguable correlation emerges. Climate science is like that and it puzzles me. I like the fractal idea of the universe – what you see on a large scale you also see on a small scale.
Zac says:
March 12, 2012 at 4:54 pm
Actually, they’re correct. They said (emphasis mine):
So they are talking, not about absolute temperatures, but the number of degrees above average, and if something is say 4 degrees Celsius above average, it is about 7 degrees Fahrenheit above average ….
w.
Cheers Willis.
Snow White takes a Walk in the Park, you’re too funny!
I posted a comment on Climate Etc. related to this topic figuring that if there was some significant water vapor input from late forming Arctic ice that we’re likely to actually see it from the NOAA Arctic water vapor animations for just about any period of time in the winter.
I noted that the principal ice loss is from the Barents and Greenland sea ice areas. I also noted the late formation of ice in the Beaufort, Chukchi, East Siberian, and Bering Seas in recent years.
I got an interesting response from Jiping you might find interesting.
Jiping | March 7, 2012 at 11:40 am | Reply
Origin of Arctic water vapor during the ice‐growth season
http://www.agu.org/pubs/crossref/2011/2010GL046064.shtml
“This change suggests that the humidity source of Arctic air masses switches in early winter from locally driven to moisture transport from lower latitudes.”
Willis, take a look at this…
James just made an excellent post, pertaining to the same thing.
Seems there are islands, that should have been covered in ice if we are to believe what Arctic “normal” ice is…..
….yet, those islands show up, and are named, on an Admiralty Chart of 1875
http://suyts.wordpress.com/2012/03/12/how-did-they-know/
Does anyone know what the actual air temperature is in the Arctic….when it’s supposed to be holding all this extra moisture?
The comments about lake effect snow got me to wondering.
Does anyone know if salt water evaporates faster or slower than fresh water given identical
temps, wind, relative humidity and baro pressure ?
Sounds like there could be a whole lotta micro-climate things goin’ on. In a not-yet deciphered pattern?
http://www.wrcc.dri.edu/cgi-bin/cliMONtsnf.pl?ak0546
there is no significant change in snow fall in Barrow, AK from 1949 to 2011
regional issue
ABSTRACT
A quality assessment of daily manual snowfall data has been undertaken for all U.S. long-term stations and their suitability for climate research. The assessment utilized expert judgment on the quality of each station. Through this process, the authors have identified a set of stations believed to be suitable for analysis of trends. Since the 1920s, snowfall has been declining in the West and the mid-Atlantic coast. In some places during recent years the decline has been more precipitous, strongly trending downward along the southern margins of the seasonal snow region, the southern Missouri River basin, and parts of the Northeast. Snowfall has been increasing since the 1920s in the lee of the Rocky Mountains, the Great Lakes–northern Ohio Valley, and parts of the north-central United States. These areas that are in opposition to theoverall pattern of declining snowfall seem to be associated with specific dynamical processes, such as upslope snow and lake-effect snow that may be responding to changes in atmospheric circulation.
Kunkel et al. 2009
JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY VOLUME 26
Heavily OT, but my newest book has just come out:
http://www.amazon.co.jp/%E3%80%8C%E5%9C%B0%E7%90%83%E6%B8%A9%E6%9A%96%E5%8C%96%E3%80%8D%E7%A5%9E%E8%A9%B1-%E7%B5%82%E3%82%8F%E3%82%8A%E3%81%AE%E5%A7%8B%E3%81%BE%E3%82%8A-%E6%B8%A1%E8%BE%BA-%E6%AD%A3/dp/4621085174/ref=sr_1_2?s=books&ie=UTF8&qid=1331603261&sr=1-2
The title, literally translated, is “The Global Warming Myth: The Beginning of the End”.
I owe much to WUWT and many contributors here. Thanks.
BarryW says (March 12, 2012 at 5:07 pm): “Central Park doesn’t seem to be a good test spot.”
Barry’s right, Willis. You should take your cue from dendroclimatology, which sifts through mountains of tree-ring records to identify and use only the “treemometers” that correlate with temperature records. Since Central Park doesn’t correlate with changes in arctic ice extent, it’s obviously not a good “snowmometer”. You should discard it in favor of locations that do correlate with satellite-measured arctic ice extent, and then you’ll finally be able to confirm the model.
Oh wow, do I have a great idea for a research grant application! Having identified strong “proxies”, I can use these locations’ snow records from the pre-satellite era to derive–with great statistical confidence–figures for historical arctic ice extent that no one else has so far been able to produce. Oh Mann, I smell the mother of all reverse hockey sticks, and it smells like money!
/sarc for the humor-impaired.
Mike Wryley says:
March 12, 2012 at 5:58 pm
The comments about lake effect snow got me to wondering.
Does anyone know if salt water evaporates faster or slower than fresh water given identical
temps, wind, relative humidity and baro pressure ?
The delivered wisdom is that fresh water evaporates slightly faster. The presence of ions of Na and Cl (and many other impurities) reduce the number of water molecules at the surface that have the opportunity and energy to leave. Sea water also boils at ~103C presumably for the same reason.
Well done, Tokyoboy, my warm congratulations on your book.
w.
A nice analysis. Yet:
In figure 3, the peaks and valleys do seem to correlate (by eye).
It may be that other processes work to help determine the total snowfall. But, maybe the autumn ice parameter does impact the final result.
I sometimes question using “standard statistics” (which implicitly assume some things about underlying distributions and causes) to prove or disprove relationships — when we don’t actually know what’s going on and don’t actually know if the statistic used applies in the specific situation.
This is a case where I, personally, would ponder what different statistical or numerical methods I might use to confirm the relationship between the sets of peaks. I would also consider other sources of data. Basically, I would try hard to prove my original conclusion (no connection between phenomena) wrong — before I assumed I was probably right.
Allen63 says:
March 12, 2012 at 8:10 pm
That’s great, Allen, report back on your results. I’ll be interested to see your analysis.
w.