Guest post by Steven Goddard
Several people keep asking why am I focused on winter snow extent. This seems fairly obvious, but I will review here:
- Snow falls in the winter, in places where it is cold. Snow does not generally fall in the summer, because it is too warm.
- Winter snow extent is a good proxy for winter snowfall. Snow has to fall before it can cover the ground.
So what about summer snow cover? Summer snow cover declined significantly (from the 1970s ice age scare) during the 1980s, but minimums have not changed much since then. As you can see in the graph below, the overall annual trend since 1989 has been slightly upwards.
Data from Rutgers University Global Snow Lab
Note in the image above that there has been almost no change in the summer minimum snow extent since 1989, and that the winter maximums have increased significantly as seen below.
Summer snow cover is affected by many factors, but probably the most important one is soot, as Dr. Hansen has stated.
The effects of soot in changing the climate are more than most scientists acknowledge, two US researchers say. In the Proceedings of the National Academy of Sciences, they say reducing atmospheric soot levels could help to slow global warming relatively simply. They believe soot is twice as potent as carbon dioxide, a main greenhouse gas, in raising surface air temperatures. … The researchers are Dr James Hansen and Larissa Nazarenko, both of the Goddard Institute for Space Studies, part of the US space agency Nasa, and Columbia University Earth Institute.
http://news.bbc.co.uk/2/hi/science/nature/3333493.stm
The global warming debate has until now focused almost entirely on carbon dioxide and other greenhouse gas emissions, but scientists at the University of California – Irvine, suggest that a lesser-known problem – dirty snow – could explain the Arctic warming attributed to greenhouse gases….The effect is more conspicuous in Arctic areas, where Zender believes that more than 90 percent of the warming could be attributed to dirty snow.
http://www.scienceagogo.com/news/20070506202633data_trunc_sys.shtml
In summary, winter snowfall is increasing and currently at record levels, and summer snow extent is not changing much. Earlier changes in summer snow extent were likely due primarily to soot – not CO2.
Why Is Winter Snow Extent Interesting?
Several people keep asking why am I focused on winter snow extent. This seems fairly obvious, but I will review here:
1. Snow falls in the winter, in places where it is cold. Snow does not generally fall in the summer, because it is too warm.
2. Winter snow extent is a good proxy for winter snowfall. Snow has to fall before it can cover the ground.
So what about summer snow cover? Summer snow cover declined significantly (from the 1970s ice age scare) during the 1980s, but minimums have not changed much since then. As you can see in the graph below, the overall annual trend since 1989 has been slightly upwards.
Data from Rutgers University Global Snow Lab
Note in the image above that there has been almost no change in the summer minimum snow extent since 1989, and that the winter maximums have increased significantly as seen below.
Summer snow cover is affected by many factors, but probably the most important one is soot, as Dr. Hansen has stated.
The effects of soot in changing the climate are more than most scientists acknowledge, two US researchers say. In the Proceedings of the National Academy of Sciences, they say reducing atmospheric soot levels could help to slow global warming relatively simply. They believe soot is twice as potent as carbon dioxide, a main greenhouse gas, in raising surface air temperatures. … The researchers are Dr James Hansen and Larissa Nazarenko, both of the Goddard Institute for Space Studies, part of the US space agency Nasa, and Columbia University Earth Institute.
http://news.bbc.co.uk/2/hi/science/nature/3333493.stm
The global warming debate has until now focused almost entirely on carbon dioxide and other greenhouse gas emissions, but scientists at the University of California – Irvine, suggest that a lesser-known problem – dirty snow – could explain the Arctic warming attributed to greenhouse gases….The effect is more conspicuous in Arctic areas, where Zender believes that more than 90 percent of the warming could be attributed to dirty snow.
http://www.scienceagogo.com/news/20070506202633data_trunc_sys.shtml
In summary, winter snowfall is increasing and currently at record levels, and summer snow extent is not changing much. Earlier changes in summer snow extent were likely due primarily to soot – not CO2.
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The global warming debate has until now focused almost entirely on carbon dioxide and other greenhouse gas emissions
What “global warming debate”? There isn’t any. It has been debunked. It’s over!
Steve Goddard (10:20:59) :
A better R^2 on your second graph of winter snowfall would be to add every point with preceding point and plot as two-year accumulated snowfall. That R^2 should show much better correlation and is still proper statistics if you state the results properly. See stat book for proper title, seems would be “The Two Year Accumulated Winter Snowfall”. Could do it for three-year of more. Might uncover a hidden high-freq component.
JonesII (11:08:36) :
“Not everything is bad news. Here, an image by NASA, of Andromeda in the infrarred:
http://www.nasa.gov/images/content/427020main_pia12832-c.jpg”
Or you can sun on your I-phone, real indulgence for a SS insomniac.
http://www.nasa.gov/topics/solarsystem/features/iphone-sun.html
I’m getting a bit tired of shoveling all this high humidity….
Sorry folks, I’m normally an avid fan of this superb website. But this discussion strand is futile. We sneer at the crazy warming gang when they extrapolate a small dataset to the point of absurdity; please let’s not do the same.
It has snowed a little, so what?. Two swallows do not a summer make.
Steve Goddard (10:20:59) :
> R^2 on the winter graph since 1989 is 0.298514013
9 significant figures? Careful – Leif will start teaching you about significant digits and error bars.
Even intelligent, educated, and well-meaning people can convince themselves of all kinds of wrong things when analyzing large volumes of data from multiple experiments. It takes extraordinary discipline to keep oneself from being led astray by phantoms.
What has been demonstrated here is that the northern Winter snow extent has very large year-to-year variability, and can not be used to support a warming trend, or a cooling trend, during all or part of the last 40 years. That is itself a useful finding.
Some of the remarks made here regarding statistics have been mistaken. R-squared, in particular, is perfectly valid as a test of the assertion that time is responsible for some of the variation. But for year-on-year variations, it is necessary to annualize it first, either with seasonal averages, as above, or some other filter that removes the yearly cycle. Applying it to the raw weekly Rutgers snow cover data for the last 40 years makes no sense, but to a Dec-Feb annual average, or a 52-week average, makes perfect sense.
@ur momisugly Sordnay (11:05:01) :
I’m trying to figure out how that is representative of reality. On Feb 12 we had one of the largest winter storms in the southeast in a long time, and it barely registers on that chart, if at all? I mean heck, you can look here:
http://ge.ssec.wisc.edu/modis-today/index.php?satellite=t1&product=true_color&date=2010_02_13_044&overlay_sector=false&overlay_state=true&overlay_coastline=true§or=USA7&resolution=2000m
And see snow cover (howbeit shortlasting) all the way to north florida, but somehow that doesn’t even register on the chart. I wonder how they calculate ‘added snow cover’ because that chart does not seem indicative of what is on the ground right now in many parts of the South East. Does that cover has to remain on the ground for a week for it to register? Doesn’t seem to jive with the reality to me, at least.
Sorry I just noticed green is ‘climatology from 95-09’ so it does make a little more sense on the graph, even if the blue/red chart doesn’t
@ur momisugly Brent Hargreaves (12:04:02) :
It ‘snowed a bit?’ This is the second highest extent in the northern hemisphere on record.
Caleb,
Snow is not a perfect reflector. In fact, because of it’s structure, fresh snow acts as a black body. The high energy shortwave radiation from the sun rapidly melts the surface which freezes to form an ice crust that is more of a reflector. But even ice is transparent like glass and the fraction of the energy reflected back to space depends on the angle of incidence. It does radiate low energy longwaves as a function of surface temperature. Much of the outbound longwave radiation from the top of the atmosphere measured by satalites is frozen cloud tops.
Quote: Steve Goddard (08:42:01) :
1. “I am completely at a loss as to what some people are disputing.”
Reply: Someone – skilled in bamboozle propaganda techniques – is purposely directing attention away from undisputed facts that would embarrass NASA and/or Hansen.
2. “We have been told over and over again since Hansen spoke to Congress in 1989, that winter snow is declining and that winter storms are moving north.”
Reply: That is exactly what the propaganda artist seeks to hide.
3. “Clearly that is not happening, quite the opposite.”
You are exactly right.
Since that fact can’t be disputed, a talented propaganda artist might direct attention to R^2, 4/3(pi)R^2, PV = nRT, or anything else to bamboozle the audience.
Thanks, Steve Goddard, for this post.
A least one of your critics is more talented in propaganda than in science.
With kind regards,
Oliver K. Manuel
I’m sorry Steve Goddard, but I think that the conclusion is largely cherry-picked from the time series and the trend is likely to be spurious. Yes 2010 appears to be a large extension of winter snowfall, but its one season.
As Leif points out, the low R2 of the points says that most of the apparent trend is scatter and not significant.
I think we have to wait a lot longer to see proof that the decline of NH snow cover since the 1960s has been broken.
vukcevic (11:42:13) :That Iphone-Sun it is undoubtely an “electric sun”, even Prof.Leif will agree.☺
1) The data does not go back that far. Like much of the over-hyped climate and weather records, it’s just no enough data to get excited about.
2) There is no increase in snowcover (predicted by AGW proponents) .
3) There is no decrease in snowcover (also predicted by AGW proponents).
…not to mention that Birkeland current in the Andromeda Nasa picture.
Question
Why is the arctic ice extent so low for the time of year despite recent cool weather? Despite cool temperatures over most of the Arctic Ocean in January, Arctic sea ice extent continued to track below normal. By the end of January, ice extent dropped below the extent observed in January 2007 etc, etc?
http://uk.answers.yahoo.com/question/index?qid=20100203092427AAzTQYz
Looks like some-one needs to ask Yahoo UK a supplementary question:
If there is global warming why has Arctic Ice Extent risen above that of 2005-6 and 2006-7?
http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png
Steve Goddard:
Is the Arctic Sea Ice anomaly graph at the following link actually saying the same thing that you’re saying about the snow? –
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/sea.ice.anomaly.timeseries.jpg
If so, or not, could you help me understand how your graph and the one at this link fit together. TIA
If I was to look at the top chart as plotting amplitude, while a sinusoidal signal was controlling the gain, I would wonder what all the distortion at the top of the range is about. Is the amplifier maxed out? Otherwise, as charted, I don’t see either way what all the noise is about.
(Pun originally unintended, but I saw it and left it in. If people are willing to let the IPCC get away with it, well then…)
Zeke Hausfather (11:30:43) :
“Perhaps a cherry-pick-proof graph would help clarify this morass.
Here is the trend to present for every week since 1966 for each season.
http://i81.photobucket.com/albums/j237/hausfath/Picture41”
Great graph. If there is more snow in the Winter and Fall, and less in the Spring and Summer, doesn’t that imply a shifting of the seasons, towards earlier Winters?
For an historical last snow remaining on a 7,000′ peak 1902-1981:
http://www.robertb.darkhorizons.org/SnowOnBally.GIF
The Young family kept this record. It corresponds roughly to the US snow extent minimums where they overlap in time.
Are there other records of this type in the US?
A proxy could be built.
Brent Hargreaves: “It has snowed a little, so what?. ”
The issue is that the Team is claiming it has snowed a lot less. Thats a lie.
Total amateur here. The last time I took statistics, we didn’t have Excel to do this for you…hell, we didn’t even have graphing calculators. So be gentle. 🙂
I’m afraid to post this, but I did the entire thing, including the first 10 weeks of 2010, and I got a flat trend line with an r^2 of 1.0. That’s 43 years of data.
I didn’t want to, but I averaged the yearly values–all I have is Excel and it won’t let you exceed 255 lines of data, and this has almost 2300. And I was in a hurry–I’ll double check it again later. If anyone knows how to increase the number of points Excel will let you work with, please let me know.
There are spikes in 1966 (partial year), 1969, and 1971. After that, it drops sharply to 1974, comes up in 1976, and then stays relatively flat till this year, but it’s only February so we’ll just have to see how that plays out. The minimum is in 1990.
Karl B. (09:05:32) Tom P is an RC mercenary. I’ve seen him at CA and this site taking pot shots.
Brent-
I agree. This is kind of a joke. Going back to 1989? Give me a graph that goes back 200 years or more and we’ll start to talk. I’m 100% anti AGW and man induced warming, but we need more then this.
We will get another ice age guys, it will happen, just give it time. Anyone who thinks climate will just stay in one state is nuts…maybe for a human life time span it may seem that way, but unless you get to live through the “flip” its hard to grasp how big the changes can be. For my kid’s future, i hope we blowtoch like no tomorrow and all the ice melts and the temps soar 🙂
I was always under the assumption winter snowcover was good for crops, but i could be wrong. Without snowcover, areas of Wisconsin have had frost depths of over 50 inches. With snowcover, my frost depth right now is 8 inches or less and its been COLD, especially at night. I know a lot of snow sucks in spring because it retards warming (albedo) and also is the cause of flooding, but a lot of that is just stupid people building in areas they shouldn’t.
Ice ages? I thought the assumption was that if winter was WARMER and summer was COLDER then you could/would build an ice sheet. The warmer winter would allow more snowfall and the colder summer would allow less melting, rinse and repeat.