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.
Robert,
Do snow extent maximums occur in the summer, or in the winter?
The graph is clearly marked as “Winter Snow Extent.”
Did you bother to read the article before posting?
carrot,
Maybe this graphic will make it more clear for you.
https://spreadsheets.google.com/oimg?key=0AnKz9p_7fMvBdHY1dGdwZXdCRVBfekVzQ0FZVENPQVE&oid=1&v=1266558324736
davidmhoffer (13:24:07) :
“Tom_R (09:12:23) :
Hmm, as I write this I realize that the photon changes direction, but doesn’t lose energy since the wavelength doesn’t change. How is energy conserved when the air molecule gains kinetic energy but the photon energy remains the same?>
My recollection is that a photon has no mass so can’t transfer any kinetic energy?”
“Leif Svalgaard (18:29:51)A photon has momentum so can give you a kick = increase your kinetic energy.”
My understanding is that the CO2 molecule absorbs the photon, thus increasing the molecule’s internal (vibrational?) energy and then re-emits a photon of the same energy and thus wavelength but in a random direction. Otherwise we have a perpetual motion machine. Have I got this wrong?
carrot eater (13:23:10) :
It’s pretty clear the problems with relying only on published works.
Raw data is better.
But you want to distract from that. And true to that form, you used the word maybe. Maybe, could, if, the infamous words of a troll.
“you can fool yourself”
I think yes, you could fool yourself more easily than most other people carrot.
And I see you attacked Steven Goddard. You people never quit.
carrot eater (15:36:52) :
Steve Goddard (08:42:01) :
“We have been told over and over again since Hansen spoke to Congress in 1989, that winter snow is declining”
Please provide a link to this statement or publication from Hansen. I’m not familiar with it.
Some schools offer courses in reading comprehension.
Steve Goddard (16:09:58) :
A lucid defense.
Good on ya!
Willis,
Thanks for the analysis. Soot would only affect late spring/summer extent, because it is covered by fresh snow the rest of the year. It requires an extended period of time with no snowfall to accumulate. And forest fires occur in the summer.
carrot eater (17:24:07) :
By the way, I’m still looking for any signs that Hansen or anybody else was proclaiming that winter snow extent was decreasing over the US. Still haven’t found it
Keep looking for that Hansen quote, keep looking. Knock yourself out carrot.
Maybe you could link your search to global warming somehow and get some funding for it: you know, join that party! Or are you already in it?
Steve Goddard (21:46:26) :
Not really. Still just looks like noise to me. I like Willis’s smooth better.
Steve Goddard (21:43:56) :
Summer is interesting in that it’s more simple. There’s a more obvious trend, and it’s more obvious why there should be a trend, with warming. It isn’t obvious to me which way the winter trend should even go with warming. It’d be complicated, with air circulation patterns affecting what you get. At least, that’s how I see it.
Seriously, I hope you gather several sources for a write-up on what is known/predicted about snowfall/snowcover. A couple modeling papers, a couple observation papers, the report for the government above, the relevant sections of the IPCC – I don’t think anybody’s written something comprehensive along these lines recently, so it’d be a helpful contribution if you got a nice overview.
carrot eater,
There is nothing simple about summer snow melt. People who have studied the problem (like Hansen) thank that soot is a primary factor. Zander says up to 90%.
I flew over Greenland during late summer 2007 (the big melt year) and the snow/ice along the western side was absolutely filthy. perhaps from forest fires in Canada.
Wait a minute…. Is there even warming in the winter months, in this region? Monthly trends can be weird.
Looking at GISS trend maps, for Goddard’s period of 1989-2010, January is getting colder in the eastern half of the US, but warmer in the Arctic to the North.
The Dec-Feb winter trend, 1989-2009, is similar, but not as pronounced. The Atlantic ocean offshore is about trendless, with some spots either way.
I have no idea what that means for winter snow, but it adds a complication.
carrot eater (22:32:56) :
A couple modeling papers
============================================
Why?
Stu (17:56:03) : Steven: Leif:
Careful, if the science is correct, the GW factor need not come in to play. Proper science will handle the GW factor itself. Do the proper science anyway; what you learn may apply to something a month from now that would directly apply to GW factor.
Time series can be problematic when re-grouped in time periods. Here’s an example. Just as Steven’s top chart’s data, I have another set of snowfall data. I graph it. It jumps up and down, down and up in big jumps all over the place. I get the R^2, its terrible, 0.03. Now if I allow myself to change the division between the years in fifteen different places no more than one week, I now have a perfectly straight line for a graph with an R^2 of one!
The only thing that happened is I allowed the big snowstorm near year end to fall in this year instead of that year. The big storm on Dec 31 was moved to Jan 1 of the following year, not actually; actually the division was moved one week. Another year I moved the storm from Jan 2, to Dec 30. That tiny 7/365 (2%) shift in the time dimension took a graph from no correlation to perfect correlation. Does that make sense? By a 2% flex in time division placement, data is either laughed as meaningless or accepted as if written in granite.
Even Feynman would shout, are you crazy, use you logic, reason, common sense for heavens sake. Statistics never takes the front seat. Statistics is a tool for ease and speed and to simplify complex questions but never overrides correct reason. PC’s came out, and in some respects, logic went out the window!
Leif, maybe you are enough of a specialist in statistics to help me here. I hit this type of problem years ago but still have no answer of the proper way to handle this. This sometimes applies to temperature series of course.
The bottom line, this type of time series can be very sensitive in the time dimension. See my point? How do you handle that proper in science and statistics? (My stat book seems to say nothing on it)
carrot eater (22:32:56) :
the relevant sections of the IPCC
================================================
Have you heard about the problems with the IPCC report?
Surely you must have.
aMINO aCIDS iN mETEORITES (22:41:12) :
It appears that Goddard is writing an article to the effect of “what was/is the conventional wisdom about winter snow trends, past/present/future”. To that end, one would have to see what the different models say, whether the models agree with each other and with past observation, and also whether the authors or IPCC authors express any confidence in those model projections.
Steve Goddard (22:38:19) :
Whether it’s more soot or more warmth, one would expect less snow either way. At least until soot decreases. To me, that makes it easier to figure out than winter, where I can’t reason which way the trend would be. That there isn’t uniform warming spatially in the winter just adds to that mess.
why would it matter what the IPCC thinks?
Have you been reading about the IPCC over the past few months?
carrot, why don’t you try to write you own paper. Your line of what is expected is your own. You don’t seem to be following what Steve Goddard is saying. I don’t know if it is intentional, unintentional, or what.
There may be other places for you to find people who you don’t have to try to steer toward what you want them to be like.
“Maybe, could, if, the infamous words of a troll.”
I don’t think you understand what a “troll” is. Somebody who despises words like “maybe” and “if” is a lot closer to trolldom then one who has mastered the use of those words.
” Steve Goddard (21:43:56) :
Robert,
Do snow extent maximums occur in the summer, or in the winter?
The graph is clearly marked as “Winter Snow Extent.”
Did you bother to read the article before posting?”
Steve, did you forget that you claimed: “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.”
Maybe you should read the article you wrote.
” aMINO aCIDS iN mETEORITES (23:13:29) :
carrot, why don’t you try to write you own paper.”
Skeptics who question assertions are just so frustrating, aren’t they?
aMINO aCIDS iN mETEORITES (23:13:29) :
Of course, Goddard will write whatever he wants. I’m only suggesting a wide scope, as I think it’d be filling a need. He can ignore my opinion. But you might note that he said he was starting with a modeling paper, so I don’t think we differ that much on the idea of whether to look at a modeling paper….
“why would it matter what the IPCC thinks?”
When a lot of people have been saying “it’s snowing a lot this winter, so therefore the IPCC and all the warmists must be wrong”, you don’t think it worthwhile to actually see what the report or the literature says on the matter? Myself, I don’t think a single winter is meaningful either which way; weather is weather, and one year is not a trend, but Goddard sees a trend since 1989. So let’s see what comes of it.
Steve,
Thanks for the response. I read the article, but it only consists of a few sentences and a couple of plots. Perhaps it’s because I’m new here, but I’m not sure what you’re trying to tell readers.
Simple (pertinent, I think) questions.
What do you think snow cover tells us about climate?
What’s the margin of error on the Northern Hemisphere Snow Cover Plot? How confident are you that you’ve got an upwards trend?
Why do you think starting a plot from a minimum in the data is a good way to tell us something useful about trends?
Carrot Eater said:
“A second-order polynomial fit would likely result in a higher R^2 value.”
The game is not to increase your R^2 by increasing the order of the polynomial. That’s generally a horrible idea.
—
Here’s what I’m trying to say…you fit linear regessions to data you think is linear. Looking at winter snow extent, it’s pretty clear to me, it’s not linear…it’s got a cuve to it. Therefore, fitting a single line to all the data doesn’t make a lot of sense.
Does anyone think there might be a problem with choosing your starting point because that’s where the trend started?