Guest post by Steven Goddard
As we have been discussing on WUWT, three of the last four months have seen top ten Northern Hemisphere snow extents and the decadal trend has been towards increasing (and above normal) snow extent during the autumn and winter. It appears that this month will achieve snow extent among the top two Februaries on record.
As you can see in the Rutgers University maps below for mid-February, the excess snow cover is necessarily found at lower latitudes. Snow cover radiates out from the pole, so the only place where snow extent can increase is towards the south.
The implication of the observed trend towards increasing snow extent is that the Northern Hemisphere autumn/winter snow line is moving southwards over the last ten to twenty years.
Daily Departure – February 13, 2010 (Day 44)
Source : Rutgers University Global Climate Lab
Daily Snow – February 13, 2010 (Day 44)
Source : Rutgers University Global Climate Lab
We see southern snow cover this year in places like Greece, Northern China, and Alabama that are not normally covered with snow in mid-February. The map below shows the “normal” snow extent measured since 1966.
Daily Climatology – February 13 (Day 44)
Source : Rutgers University Global Climate Lab
Some people have been claiming that the anomalous snow this winter is due to warming temperatures. The New York Times reports on the record snow :
Most climate scientists respond that the ferocious storms are consistent with forecasts that a heating planet will produce more frequent and more intense weather events.
It doesn’t make a lot of sense that warming temperatures would cause the snow line to move south. Lower latitudes normally receive rain rather than snow, because the air is already too warm for snow. Further warming would be expected to move the snow line north – not south – and that is exactly what the climate models predict. Indeed, Time Magazine claims that this has already happened: “large-scale cold-weather storm systems have gradually tracked to the north in the U.S. over the past 50 years.”
As far as snow depth goes, Washington D.C. recently broke their 1899 snow record of 54.4 inches and now has a new record of 54.9 inches. We are told that the new record is due to “extreme weather” caused by “global warming.” If so, what caused the nearly identical “extreme weather” over a century ago? Alarmists tell us that heavy snow used to be caused by cold, but now is caused by warmth. The 1899 record was set long before the hockey stick brought temperatures to “unprecedented levels.”
Now lets take their poor logic one step further. Ice ages occur when the snow line moves very far south. If “most climate scientists” are claiming that global warming is causing the snow line to move south, then the logical corollary is that ice ages are caused by further warming temperatures. Clearly that is not true.
Wikipedia map of the last ice age
Furthermore, Hansen correctly tells us that as the snow line moves south, the earth’s albedo increases causing further cooling.
The sensible theory is that the snow line moves south when the climate is cold, and north when the climate is warm. And the record snow we are seeing this winter is due to cold, not warm temperatures.
Today’s NBA All-Star game in Dallas is covered with snow. Last time I checked, Texas was in the South.
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Gail (10:28:37) :
Enter “Rotten Ice” in WUWT’s searchbox. You find this:
http://wattsupwiththat.com/2009/12/14/a-look-at-sea-ice-compared-to-this-date-in-2007/
Steve Goddard (11:29:34) :
stephan,
Tom P made a valid point. The first version of the spreadsheet had an error and he caught it. I appreciate him pointing it out.
You don’t fool us, Steve Goddard! What with your seeming willingness to accept that you made a mistake and needed to correct it, implied openness to dialogue with your critics, and measured statements! Quit subverting our attempts to demonize you!
Interesting perusing RC these days.
Jones said, “For it to be global in extent the MWP would need to be seen clearly in more records from the tropical regions and the Southern Hemisphere. There are very few palaeoclimatic records for these latter two regions.”
So Ruth asks on RC (paraphrased): If that’s the case, with not enough Southern Hemisphere records, how can one have confidence in the 1,000 yr climate reconstruction.
The argument over seasonal snow extent trents is silly in the extreme. The Rutgers data is from the late 1960’s to late 2000’s. It shows warming half of the PDO cycle.
If the same trends could be shown for a full PDO cycle, either side of the argument might have some validity. As it is all you are doing is fitting linear trends to a partial sine curve – not very convincing.
Robert,
Perhaps you’re confusing winter snow-pack with glaciers.
Glaciers comprise hundreds of years of snowfall that didn’t melt.
If your point is that ice from another century is the happy inheritance of today’s farmers, because it is melting faster than it’s being replaced, okay; but you make it sound like they can have their ice and drink it, too.
Icarus : “quantity of precipitation is related to atmospheric moisture content, not temperature. ”
That is not exactly true. Warmer air can hold a greater amount of moisture without needing to release it in the form of precipitation. Cooler air needs less moisture in order to trigger precipitation. So to say that temperature is not related to quantity of precipitation is inaccurate at best.
Any given parcel of air can have a large amount of water contained within it, yet until that air reaches the temperature at which relative humidity is 100%, it cannot rain. Obviously there is a huge interplay between moisture content and temperature in the creation of conditions for precipitation.
This does not mean however that increased temperature necessarily means less rain because increased temperature also causes increased evaporation, as has been mentioned in other comments. So in some cases it would lead to more rain and in some it would lead to less. Some probably reach homeostasis.
That’s part of my confusion about the predictions of less water and less rain everywhere because of global warming. In some places in the world it is hot and dry, in others hot and wet, yet the media often portrays warming as something that only causes lack of precipitation. Where I live afternoon heating often leads to refreshing and welcome evening showers.
The South is Moving Snow.
If the glaciers didn’t run off they would be around longer.
Doug in Seattle,
The point of the article is to demonstrate that recent shifts in snow patterns are not due to global warming. There is no intent here to forecast future behaviour.
James Chamberlain (11:28:49) :
Everything is consistent with AGW. Now, we’d like you to go ahead and give us 5% of your money and income (EVERYONE, that is) so we can get on with the business of saving the world!
That is consistent with AGW
If GW causes more snow and/or snow cover that’s clearly a negative feedback which will lead to eventual cooling. If it’s not GW then it’s just business as usual variability.
For skeptics it’s a win-win situation.
Scarlet Pumpernickel (00:38:45) :
Watch OUT! Soon the glaciers will start growing again and it’ll be panic stations, they’ll be engulfing towns.
I believe that some Alaskan, Canadian and the Greenland Ice sheet have been adding mass for the past two years. I suspect that the same is true for some Sierra and Cascade glaciers also. Glaciers have been known to be stealthy by adding mass while at the same time appear to be receding.
It is safe to assume that precipitation equals evaporation. If the oceans warm and there is more evaporation, then the change in precipitation has to match. The law of conservation of matter requires this.
Re snow extent increasing and an ice age approaching, Eureka (California) has only 67 more years of ice-free climate:
http://sowellslawblog.blogspot.com/2010/01/eureka-ca-headed-for-ice-age-in-67.html
Steve Goddard,
re precipitation matching evaporation, that is only true at steady-state. If the air is indeed warming ( a non-steady-state condition), then evaporation can increase without changing precipitation. This is the changing inventory component. The opposite is true for a cooling atmosphere.
Roger,
The amount of moisture stored in the atmosphere is very small and long term changes in atmospheric temperature are also very small. Within reasonable measurement error, precipitation equals evaporation.
Richard M,
Alarmists seem to be claiming now that the snow line moves south from warming, and it also moves south from cooling. The implication being that any change in the climate causes the snow line to move south. If they are correct, then the earth is always moving into an ice age.
joe (10:55:27)
Here’s a pdf map from SMHI showing Baltic Sea ice conditions.
http://www.smhi.se/oceanografi/istjanst/produkter/sstcolor.pdf
Steve Goddard (15:53:51) :
If they are correct, then the earth is always moving into an ice age.
And such proclamations about warming causing cooling is due to wandering about in a Desert devoid of calm reasoning for many decades.
Steve Goddard (10:51:33):
“There was an error in the spreadsheet.”
Glad to see you’ve untangled your maths. So the winter trend for your chosen period of the last twenty years is +52,000 km2/year, and is not statistically significant.
But the overall trend for the annual measurements is a much more substantial snow loss, -89,000 km2/year since 1966.
Your headline that the snow line is moving south has no basis in observation.
Tom P (16:49:43) :
The real world of people caught up in severe snow storms is not a trend line, southerly or otherwise.
It does not matter one bit to them how you might minimalize the condition: the condition exists, and precious few there were to prepare them for what should have been emphasized months ago.
We saw what was happening in the S. Hemisphere last summer, and we posted what we perceived was coming. Everyone who frequents this place is well-aware of what that portent was. Behind the veil of Xth warmest month on record portrayals was a hopscotch of increasing cold and snowy winters.
The forecast that was put out was not for what was coming, but what was politically correct, and that hurts more than anything else.
If Phil Jones can man up to the uncertainty and the inability of statistics and trend lines to accurately portray the real world, so can you.
This isn’t a game about who can snow whom over what numbers, it’s about real people on the real ground in the real world who need help.
They have been so far grossly mis-served.
What do you have for those people?
It is true that warm oceans can produce increased snowfall *in the higher latitudes* of continents, warming would not move the snow line *south*.
Warm oceans would indeed evaporate more, and warm atmosphere can certainly hold more water. Who doubts that?
But that would give you more snow in the Rockies and in Labrador, not in Georgia and South Carolina.
I have much appreciated the gentlemanly debate style in this thread. I have learned from both points of view.
Simply, the snow happens where warm meets cold.
If the warm-meets-cold line moves north, the snow happens further north.
If the warm-meets-cold line moves south, the snow happens in the south.
Why does the warm-meet-cold line move? The simplest answer is because the planet as a whole is warming or cooling.
Oh sure there are some complex bits involved. Wind and water currents mix it up a bit. But apparently the snow line has moved south for the entire northern hemisphere.
Warming cannot make the snow-line move south. Warming only makes the snow-line move north.
Tom P,
I admire your persistence. The trend since 1979 is very significant, and 2010 (so far) is a particularly interesting year.
https://spreadsheets.google.com/oimg?key=0AnKz9p_7fMvBdHFzTFVnTlVrYnV0bEpxLWt5aXE2UEE&oid=1&v=1266293307202