While some other bloggers and journalists insist that recent winter snows are proof of global warming effects, they miss the fact that models have been predicting less snow in the norther hemisphere. See this 2005 peer reviewed paper:
Frei, A. and G. Gong, 2005. Decadal to Century Scale Trends in North American Snow Extent in Coupled Atmosphere-Ocean General Circulation Models. Geophysical Research Letters, 32:L18502, doi: 10.1029/2005GL023394.
It says exactly the opposite of what some are saying now. – Anthony
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Guest post by Steven Goddard
A 2005 Columbia University study titled “WILL CLIMATE CHANGE AFFECT SNOW COVER OVER NORTH AMERICA?” ran nine climate models used by the IPCC, and all nine predicted that North American winter snow cover would decline significantly, starting in about 1990.
In this study, current and future decadal trends in winter North American SCE (NA-SCE) are investigated, using nine general circulation models (GCMs) of the global atmosphere-ocean system participating in the upcoming Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC-AR4)…
all nine models exhibit a clear and statistically significant decreasing trend in 21st century NA-SCE
Some of the models predicted a significant decline in winter snow cover between 1990 and 2010.
Climate Model predictions of Snow Cover Decline
As we know, winter snow cover has actually increased about 5% since it bottomed in 1989, and is now close to a record maximum.
Below is another interesting graph. It shows the number of top 100 snow extent weeks by decade. I took the top 100 weekly snow extents (out of 2227) from the Rutgers record and sorted them by decade. The past decade has been at least as snowy as the 1970s.
The past decade has had the most weeks in the top 100 since 1966.
Above are images from NASA showing snow extent from 2001 to 2004. Below is an image from 2010, showing snow cover in all 48 states.
NOAA Image – February 12, 2010
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UPDATE: Here is a new graph of north American winter trend produced by Steve at the request of commenters:
So far, the climate models have the wrong polarity on their predictions of winter snow cover changes.
As a further sign that all the snow is due to global warming, Europe just came within a couple of degrees of breaking their all-time record lowest temperature.
http://www.accuweather.com/mt-news-blogs.asp?partner=forecastfox&blog=Andrews&pgurl=/mtweb/content/Andrews/archives/2010/02/nearly_an_alltime_record_low_in_europe.asp
Given that the earth is neither covered with ice nor ice free, it is axiomatic that if you measure snowfall trends over a long enough period of time, the slope is necessarily close to zero.
That in no way indicates that there are not periods of time when snowfall increases or decreases. Climate is neither linear nor monotonic. This obsession with trying to fit long periods of climate data to straight lines is irrational. Longer is not necessarily better. Sometimes it is better to use scientific judgement rather than jumping into meaningless statistical analysis.
to:Crispin in Waterloo (00:35:39)
Thank you, you put into words what has been bgging me about the “warmer = more moister = more precipitation = more snow in winter” AGW remix argument. RH, of course! More argument down the pub (bar)….
Steve Goddard (08:22:11) :
As a further sign that all the snow is due to global warming, Europe just came within a couple of degrees of breaking their all-time record lowest temperature>
Steve, Steve, Steve,
We’ve already had it explained to us that Europe was warm for a couple of centuries but it was “local”. So I imagine this is just “local” too, Europe as a continent doesn’t participate in global climate.
BTW found that Red River Basin tree ring study, page 13. Don’t tell Briffa or Mann that the oak trees in my back yard have called his larch trees liars, they’ll try and core them or something. The study doesn’t purport to be a temperature proxy, they even show that temperature has a slight negative affect. But if you DID look at it as temperature, Briffa et al would have some explaining to do. The curve doesn’t look like the long term European curve, but we’re way inland here, so ocean current don’t affect us the same way. That said, lots of growth a few hundred years ago that exceeds current. I checked to see if the major floods showed up, and they did not, further evidence that all kinds of important things happen in the winter that tree rings don’t measure.
http://www.gov.mb.ca/stem/mrd/geo/pflood/p_pdfs/climaticextremesinsmb.pdf
threw a quick post up on my blog if you just want to do a quick compare:
http://knowledgedrift.wordpress.com/2010/02/21/red-river-and-red-oak-speak-out-larch-trees-lied/
Tamino suggests:
“If we look at monthly snow cover anomaly for all months of the year covered by the Rutgers data we see a long-term decline of 37,000 km^2/year, which is statistically significant:”
http://tamino.wordpress.com/2010/02/18/cherry-snow/#more-2308
He suggests that January shows no decline and that Goddard has omitted data prior to 1989.
Any comments please ?
Dr. A Burns,
The article is about model predictions of winter snow cover. Winter is the season when snow cover is maximum. Please reread and try again.
I don’t know how you can compare reality to predicted without discussing the stated error bar ranges of the predictions. Given the annual and decadal variability in winter snow cover I would estimate that any GCM derived 20-yr prediction would be something like -.01 +/- .15 million sq km/yr in which case the model prediction is not invalidated. The effect of climate change over 20 years is so minimal it is drowned out by natural variation. I assume that studies predicting winter extent contained formal error estimates due to natural variation, and would be interested to see if the observed trend falls outside of those predicted error ranges.
Andrew P,
This winter has been a near record setting winter for snow cover. Is that confirmation of a model which predicts declining snow cover? The winter of 2008 saw the third greatest snow extent ever recorded. Is that consistent with models that predict declining snow cover?
In science, predictions are never confirmed they are only invalidated. I do not know if these model predictions have been invalidated because I do not know what their stated error range is for a 20-yr prediction. As I said before, because on a 20-yr timescale natural variation would drown out almost any climate signal, my guess is that the observed trend is not outside the error ranges. But without knowing the error ranges for these models, none of us know.
Any regular WUWT reader should be familiar with these types of calculations. Several authors here and people cited here have shown that GCM temperature predictions are on the edge of being invalidated. That is, the observed 12-yr temperature trend falls just inside the lower bound error range given by models. Were we to see a return to recent ’08-09 temperatures following this El Nino, they would be statistically invalidated outside of a 95% confidence interval, as the work of some like Lucia have shown. You haven’t performed such an analysis.
Yeah, but that still gives the warmists a nit to pick, by claiming that your trend doesn’t meet 95% significance level. It would be better to make a more modest claim that leaves them with no comeback. For instance, by quoting the exact words of some of their predictions, and then showing how they have failed to come true. That’s enough. Anything more offers them an opportunity to raise a diversion that clouds the essential issue.
Andrew P,
Statistical analysis would be interesting if were predicting a trend into the future. I am not making any predictions, so the statistics are meaningless and an unwanted distraction.
It is quite clear that the negative projections of the GCMs have been incorrect so far. It requires no statistical analysis to see that snow extent has not been declining the last twenty years.
If the current 20-yr observational trend is within the range of error predicted by the models then they are not incorrect.
If I predicted 6-12″ of snow tomorrow and we got 11.5 would you say I was wrong because we didn’t get exactly 9?
Andrew P,
Climate models predicted declining winter snow extent. Snow extent has increased. If the error bar is great enough to absorb the opposite polarity, then it isn’t much of a forecast, is it?
No, it probably was never intended to be much use at forecasting on 20-yr timescales. I’m sure the error range for the trendline decreases rapidly for longer time periods in which natural variability would play a smaller role than climate change. That said, I wouldn’t be surprised if the trend has been so positive for the last 20 years it falls outside the error ranges or just inside them. I was just commenting that we can’t know but I would be curious if you could find a source which tried to quantify the error range. You also have to be careful because the 20-yr trend MIGHT be outside the error range but the 30-yr trend is not. Basically your conclusions cannot be very strong or interesting unless you show the models are invalidated by having an observed trend line outside of the error ranges for the models which would be pretty large for a 20 year period.
Insane…global warming is such a misuse of the characterization of what is going on. Climate change means that there is more energy in the atmosphere (at least, this time around) and that the global and regional weather patterns are going to become more erratic and extreme. A temperature change of 20C to 30C still means that it can snow, but the higher temperature means that there can be more humidity in the air, and as a result more snow. The truth is that the science is getting better, and the need for accurate and un-biased data has never been needed more than now.
And besides…petroleum makes our enemies rich. Who cares about the climate? We’re all gonna be dead before the sh*t hits the fan anyway.
IT’S TOOOOOOOOOO LONGGGGG