Snow White Takes a Walk In The Park

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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John A. Fleming

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.

Eve

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.

Willis Eschenbach

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.

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.

BarryW

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.

Steve from Rockwood

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.

Willis Eschenbach

Zac says:
March 12, 2012 at 4:54 pm

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/

Actually, they’re correct. They said (emphasis mine):

Laptev, Kara and Barents seas ranged from 4 to 8 degrees Celsius (7 to 14 degrees Fahrenheit) above average

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.

John from CA

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.”

Latitude

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/

Latitude

Does anyone know what the actual air temperature is in the Arctic….when it’s supposed to be holding all this extra moisture?

Mike Wryley

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?

crucilandia

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

crucilandia

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

tokyoboy

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.

Gary Hladik

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.

Ian W

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.

Willis Eschenbach

Well done, Tokyoboy, my warm congratulations on your book.
w.

Allen63

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.

Willis Eschenbach

Allen63 says:
March 12, 2012 at 8:10 pm

… 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.

That’s great, Allen, report back on your results. I’ll be interested to see your analysis.
w.

uhi. reduces snowfall.

Gail Combs

tokyoboy , Congratulations!

Hi Willis
Is there any work done on the Southern Hemisphere?
I ask beacuse last winter here saw snowfall during mid-August in Wellington down to sea-level for the first time in 20 years, and snow actually fell in Auckland which I think is the first time in living memory
Also am I to believe Antarctic Sea-Ice to be increasing – so a SH correlation shouldn’t exist – yet we had record snow!!!
Andi

Thrasher

BOS (Boston, MA) and ORH (Worcester, MA) data in New England both show very large increases in snowfall during the last 20 years despite declining sea ice, so its not just New York.

Congratulations, Tokyo Boy!
Please let us know how it’s received, what the reviewers and the media have say. Any chance you might submit an English summary to WUWT? Staring at the cover, reflexively (and insipidly) waiting for the text to somehow resolve itself into comprehensible letters and words for me, I came to a better appreciation of the frustration illiterate people must feel.
Very cool (actually “hot”) Hokusai-like cover, that one. Speaking of whom, I recalled a re-rendering in “warm” hues of one his most famous works from his Mt Fuji series and by some miracle found it again. That one would work for a translated English edition or article, as the image is iconic in the West as well: http://toastified.deviantart.com/art/Hokusai-Revisited-102717156
All the best and may your book spread far and wide throughout your beautiful island nation!

Gary Hladik

steven mosher says (March 12, 2012 at 9:12 pm): “uhi. reduces snowfall.”
Which raises the question: If Central Park UHI since 1979 is significant enough to affect snowfall, are the official adjustments–in such temp indexes as GISS produces–adequately compensating for it?
I’m wondering if it’s possible to remove the UHI/snowfall effect, if any, by tracking winter precipitation instead of snowfall.

Les Johnson

Willis: I agree with Mosh. UHI reduces snow, and especially ice. Rain falls, temps drop, water freezes. For snow, it has to have a greater UHI to affect whetther it remains snow, or falls as rain. UHI would eliminate more ice than snow.
It might be better to look at winter precipitation, to see if any correlation exists.

oMan

Love the last chart. It does indeed show how we want to see patterns, whether or not they’re present. I might go further and argue that “chartiness” is part of this: whenever we see two lines on a chart, we start trying to figure out how they correlate. Blame it on kindergarten and those learning games: “kids, what is wrong with this picture? Can you see five cats in the tree?”. Etc.

Willis Eschenbach

steven mosher says:
March 12, 2012 at 9:12 pm

uhi. reduces snowfall.

Possible. Got a better data source than the Park?
w.

Hector Pascal

@tokyoboy
Greetings from Yamagata, and well done. I will show that to the good lady, and see if she’s interested.
On snow. We’ve had 20cm over the past 2 days. Unheard of for this late in the winter. Total snowfall this winter is going to be around 16 metres plus.

Agnostic

Good on you for looking at this again Willis.
My slight problem with this is the “loaded dice” caveat in the paper. They propose that the first significance of low sea ice is the extra humidity in autumn affects the wind patterns in the area. The extra humidity in cold air coming from the arctic region is only of secondary importance.
But the paper does explicitly say that low sea ice is not the only factor. Could I suggest taking a look at the correlation with in particular ENSO to see if strong a El Niño will override the tendency to bring more snow in early winter that might normally have come due low sea ice extent.
A second point is that the spatial distribution of sea ice may also be a mitigating factor. If the sea ice extent is evenly distributed, or not sufficiently open enough, it may not allow for strong enough increase in humidity localised to create a change in the atmospheric wind pattern.
I think what is proposed by this paper is a piece of a climate jigsaw, that when considered with other pieces may help with seasonal forecasting. Just looking at a straight correlation between sea ice extent and snowfall is not sufficient.

John Marshall

Their Abstract claim ‘Strong Arctic Warming’ over the past few years. I would like their definition of Strong. Oh hang on their models show this warming so the claim must be OK.

George Tetley

majormike1
Great link, see what you can do without models, if the word logic is still permissible in a scientific discussion I think Ewing and Dunn got it right !

George Tetley
George Tetley

The link to majormike1 was written in 1958,

Agnostic

Actually slight correction to my previous post, it’s the reduced temperature differential that affects the wind patterns. The extra humidity is of secondary importance.

Hector Pascal

@tokyoboy
The good lady is back from work (8pm). Her translation:
The Myth of Global Warming
by: Tadashi Watanabe.
Watanabe san. Thank you for your effort.
For those outside Japan, the government has received advice from its scientists that AGW science is too uncertain to inform any meaningful policy decisions. The advice is to do nothing and wait. The Japanese government therefore will enact no policies to disadvantage Japan’s manufacturing WRT industrial competitors. That includes withdrawing from the Kyoto Protocol.

> But folks said, and fairly, that I wasn’t really dealing with their claim.
I think its good that you’ve realised that your previous analysis was all beside the point, though it was a bit of a shame that you didn’t say so at the time. You’ve made an attempt to do better, but you’re suffering from drunk-looking-for-keys-under-lamp-post syndrome: you’ve found a good dataset, but probably not one that is good for this problem.
As before, you need to go back to the paper, and look at, say, their figure 7. Where you’ll notice they have plotted land-only, and masked out the coastal grid points. So a dataset from the coast isn’t a good idea. You want somewhere from 70N 60E, say; or maybe 110W 62N ish. You might be better off working with the reanalyses.

Kip Hansen

Willis,
I’m from NY, both Upstate NY (everything above Westchester County) and the analogous-to-NYC Northern New Jersey Bergen County. Snowfall in Central Park is not a good metric for Northeast US snowfall at all. One can have a foot of snow in Bergen County or Western Connecticut and see an inch in Central Park. Three feet in Albany, NY and nothing in Central Park. It just doesn’t really relate. Central Park is on Manhattan Island, surrounded by warm water–thus has the ‘shore effect’– and a hot city.
Big mistake — apples for oranges adding up to bananas.

tokyoboy

“Hector Pascal says: March 13, 2012 at 4:16 am ………….”
Thanks Hector, and thank you friends for your attention.
But I’m now quite sorry for eating up much space with an off-topic issue, on this fascinating thread by Willis.

D. Robinson

Willis, how about snowfall at Mohonk Lake, NY?
http://www.wrcc.dri.edu/cgi-bin/cliMONtsnf.pl?ny5426
There’s a long time weather station there, which has been written about previously. Not sure if the elevation hurts the discussion or not.

Stomata

Be aware of sudden adjustments by CT, NORSEX, NSCD even DMI when ice is like this
http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic
they basically cannot afford to have ice within the normal area for too long. Its all tripe anyway as we can see they have eecided to not show data from before 1979 and their baseline is therefore junk see real-science http://stevengoddard.wordpress.com/

Vincent

Not being a New Yorker, I’m a bit uncertain, but I think Central Park is in the middle of an urban heat island. So is it really valid to use it as representative of a region?
The same was true when I lived in London more than 20 years ago – snow in the City was unheard of, but it could occur in the surrounding countryside. (OK, I admit, the Thames is probably a confounding factor !-)
Regards
Vincent

Willis Eschenbach

D. Robinson says:
March 13, 2012 at 7:35 am

Willis, how about snowfall at Mohonk Lake, NY?
http://www.wrcc.dri.edu/cgi-bin/cliMONtsnf.pl?ny5426
There’s a long time weather station there, which has been written about previously. Not sure if the elevation hurts the discussion or not.

Thanks, D. I took a look. The correlation with Central Park is not bad, about 0.5 for the period post 1979 (p less than 0.001).
But the Mohonk Lake correlation with the autumn arctic ice levels is actually WORSE than for Central Park. For the non-detrended data, the r^2 is 0.07 (p=0.12), and for the detrended data r^2 is 0.01 (p=0.64).
So all of you folks that have been claiming that UHI is the reason the effect didn’t show up in the Central Park data?
Sorry, but you were wrong. Usually, I wouldn’t take pleasure in pointing this out, but it’s been pointed out in an unpleasant fashion by useful idiots like Billy Connolley, who said:

I think its good that you’ve realised that your previous analysis was all beside the point, though it was a bit of a shame that you didn’t say so at the time. You’ve made an attempt to do better, but you’re suffering from drunk-looking-for-keys-under-lamp-post syndrome: you’ve found a good dataset, but probably not one that is good for this problem.

Sorry, Billy, but as is becoming a habit with you … you’re wrong again. Perhaps you’re suffering from the old “drunk-looking-for-his-brain-under-a-lamp-post” syndrome …
Also, you say my previous analysis was “beside the point” … actually, that’s what we’re trying to determine here. It’s called the “scientific method”. I said if there was a serious or significant effect, it would show up in the data for North America. But heck, it didn’t show up there.
People said it didn’t show up, not because it was too small, but because it was a local effect. And yes, it’s possible that it’s a local effect … but we haven’t found that one either.
That means that my previous analysis, far from being “beside the point”, actually is correct so far. We haven’t found the claimed effect anywhere.
So … more datasets? Anyone?
w.
PS—I also find it quite significant that the claimed effect is more visible in the non-detrended data, and disappears entirely when we detrend both datasets.
This means that the effect is not operating on a year by year basis … which makes it very likely that the somewhat greater (but still not statistically significant) correlation using the non-detrended data is only an artifact.

Eyal Porat

For a true scientist, the collapse of a theory leads to change of view and abandoning it.
For the “New Scientists”, it leads to bending of facts and torturing of data.
It never is an option for them to seek a different direction and alternate options.
Oh so sad.