Guest post by Dr. Richard Keen
The winter of 2009-2010 was a memorable one in the Northeast and Mid-Atlantic states, with locations like Philadelphia enjoying multiple massive snow storms that led to record totals for the winter. As with all exceptional weather events of late, the usual suspects blamed the occurrence on global warming. In a NOAA press release reported in USA Today (http://www.usatoday.com/weather/climate/2010-07-15-heat-record_N.htm), Jay Lawrimore stated that…
Heavy snow, like the record snows that crippled Baltimore and Washington last winter, is likely to increase because storms are moving north.
To which I commented on “Watts Up With That” on July 16, 2010 ( http://wattsupwiththat.com/2010/07/16/a-spot-check-on-noaas-hottest-so-far-presser/ ) that Lawrimore’s remarks show a complete lack of understanding of weather (which makes up climate).
Anyone who spends a few winters on the East coast knows that snow there is generally caused by lows off the coast, and if the storms move north (as Lawrimore claimed), Baltimore, Philadelphia, NYC et al. find themselves in the warm sectors of the lows, and enjoy warm southerly winds and rain.
That’s the theory; how about some data to show that a warmer climate should lead to less snow, not more. The data are easy to find and interpret. More than a century of winter snow totals and average winter temperatures (December-January-February) are posted on the NWS Philadelphia web site. Seasonal snow totals in Philadelphia are dominated by the occurrence (or non-occurrence) of large snow events (i.e., the snowiest winters have two or three major storms, and the least snowy winters had none). Here’s some charts and correlations.
Chart 1 compares yearly winter snow totals (in blue) with winter mean temperatures (in red). The small circles are for individual winters, and the heavy lines are 30-year running means (since climate is defined by some, such as the WMO, as a 30-year average). The winter temperatures are plotted upside-down to show the correlation better. And the correlation is that warm spells, like those in the 1930s, 1950s, and 1990s, have less snow overall than cold epochs like the 1900s, 1910s, 1960s, and 1970s. Note that the 30-year running means are plotted and the end of each 30-year period, so while the 30-year means are shifted a bit from the highs and lows of the annual values, the 30-year curves for snow and temperature line up together. Also note that over 126 years, Philadelphia’s winters are not getting warmer or colder, and there’s not much change in snowfall.
Chart 2 is a direct comparison of yearly snowfall with winter temperatures. The correlation coefficient (square root of R2) is greater than -0.5, which is not bad for anything in climate. It clearly shows a trend for more snow during colder winters, and less snow during mild winters. Philadelphia’s average annual snow fall is 20.5 inches, and the coldest winters produce about twice that amount, while the warmest winters are almost snowless.
The occurrence of snowy and less snowy winters during cold and mild winters is summarized in the table below. Although half of the winters are warmer than the median temperature (of course!) and half are colder, and half of the winters are snowier than median and half are less snowy, the co-occurrence of snow vs. temperature is not so even.
There are several ways to describe the relation between winter temperature and snowfall….
- Colder winters are three times more likely to be snowier than the median.
- Snowy winters are three times more likely to be cold.
- Warm winters are three times more likely to have less snow than the median.
- Less snowy winters are three times more likely to be mild.
One way the relation between snowfall and winter temperature CANNOT be described is that warmth leads to more big snowstorms and greater total winter snowfall.
By the way, I did this analysis for Philadelphia because it’s where I was raised and learned about weather before moving to Colorado. The warmers will no doubt raise their usual charge of “cherry-picking” when inconvenient data shows up. I challenge them to examine others locations in the northeast to find one they can “cherry pick” to support their claims. Until they do, the recent large snowstorms stand not as a symptom of global warming, but as yet another indication that global warming may not be happening at all.
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Well, biologists studying the some 2 million dead fish in Chesapeake Bay think they died due to cold stress. No doubt another symptom of global warming.
http://www.baltimoresun.com/features/green/bs-gr-fish-kill-bay-20110104,0,5624655.story
100 million cubic meters of ice melted into steam by Eyjafjallajokull help?
P. Solar says:
January 5, 2011 at 4:57 am : So, P, if it’s GLOBALLY (sic) warmer, wouldn’t it be warmer in PHILADELPHIA?
P.Solar says.
“As I understand it, the warmist proposition here is that snow is a form of precipitation and that GLOBALLY warmer temps will lead to increased precipitation in affected areas.”
The only question to ask about weather is what weather denotes no global warming? If you cannot state the weather that denotes no global warming you cannot know the weather that does.
No credible climate scientist is or would ever link any individual storm, drought, heat wave, rain or snow event to AGW. No credible climate scientist would ever link one or two year’s worth of temperature extremes to AGW. AGW (if it is happening) is a long-term event caused by the long term accumlation of GH gases since about 1750 or so.
One would only expect the FREQUENCY of certain kinds of events to increase over a given period and a general upward bias in temperatures when looked at on a decadal time scale. Generally, since every GCM predicts an acceleration of the hydrological cycle, and there is global evidence of this occurring, then in areas that normally can get heavy snow or rain events, you’d expect to see an increase in the frequency and magnitude of such events over a longer term period (decades).
http://www.climatestations.com/images/stories/chicago/chiaan.gif
Chicago has been spared. Hottest year was 1922, coldest was 1875, four out of the last seven have been below average.
I would love to see this from as many cities as possible!
Are links disabled here?
Chris Riley, I think you described the situation accurately.
With regard to snowfall…there may be more, but it’s a warm snow.
What seems to be the new paradigm is that carbon “pollution” is causing “extreme events”. That is if you can’t get the theory to fit then use one that will always give the impression of always fitting. A pile of desperation horse dung .
Bob says: January 5, 2011 at 6:08 am
Might one assume that you have a better chance of rain when it is warmer?
If you are in Darwin, yes. If you are in Melbournr, no.
Q: Are huge northeast snow storms due to global warming?
A: Of course – everyone knows that the snow to be warmer than it used to be…
Just had the MET office on the BBC, apparently the underlying trend of global warming is causing larger weather fluctuations, floods, snow and heat. Their answer? They want more money for an even bigger computer so that they can ‘understand it better!’
Apparently the lack of ice in the Artic is somehow to blame for the cold snaps we’ve had in the UK.
But they did accept there was a thirty year or so cycle in weather patterns. I guess that’s the get out clause.
But as always they come back to AGW, clusters of Winters, I guess they had to explain away the mild forecasts and BBQ Summers somehow…
http://www.bbc.co.uk/news/science-environment-12119329
What’s the US weather forecaster’s excuse?
This simply doesn’t disprove what it says it does. I’m skeptical of their argument, but it IS inherently obvious that colder = more snow. The argument is that the change to the overall climate system means more snow, and the only way to demonstrate that would be to chart global temperature VS. amount of overall rainfall.
There’s basically 2 factors that go into whether it snows (simplifying heavily, of course): temperature and amount of moisture in the air. The argument is that since temperature will be higher all of the time, there will be more evaporation, so more moisture will fall when it IS cold. The question is whether:
(More Temperature Effect) X (Less Moisture)
is more or less than
(Less Temperature Effect) X (More Moisture)
This isn’t well enough supported, but it is certainly less stupid than MORE FLOODS AND MORE DROUGHTS.
Ugh, let me clarify my own post.
It IS inherently obvious that colder = more snow LOCALLY.
And the last word of the first paragraph should be snowfall, not rainfall.
Dr Keen: “Sorry, I’m not missing the point, and I do address this issue. The data shows that colder equals snowier, so the warmer equals wetter hypothesis simply doesn’t, well, hold water. Remember, Lawrimore et al. said that warmer equals snowier, and that’s wrong.”
I doubt that you are accurately resuming Lawrimore et al findings in three words “warmer equals snowier”. In any case that is a distraction. We are not discussing Lawrimore et al. , we are discussing what you presented in this article .
“The data shows that colder equals snowier”. So in reply to my critisism you simply say the same thing in a louder voice. Lets try again…
Your LOCAL data shows LOCAL cold correlated to LOCAL snow.
Your LOCAL data does not give any information about the effect of GLOBAL warming on LOCAL snow. In what way do you claim to address the question that you pose as the title here?
Sadly , it seems that the volume of postings at WUWT is inversely proportional to the quality.
Apart from the usual whoots and catcalls from a fauning public , I see less and less content here that merits discussion.
That is unfortunate since the writing is on the wall for AGW and now is the time to attack it with science, not ill-concieved monologues that can easily be dismissed as unsound or irrelevant.
Anthony, please be more exigant.
The correlation coefficient (square root of R2) is greater than -0.5, which is not bad for anything in climate.
Yeah, people keep forgetting that square roots of positive numbers can be positive or negative. Then there are the square roots of negative numbers, certain computer programmers insist their existence must be imaginary.
Where are the real science people who have told us in the past that an R^2 less than around 0.95 (sq rt +/- 0.97) just means your theory ain’t good enough, go find a theory that actually works?
Your LOCAL data shows LOCAL cold correlated to LOCAL snow.
Your LOCAL data does not give any information about the effect of GLOBAL warming on LOCAL snow. In what way do you claim to address the question that you pose as the title here?
In what way does using a global data set override the local physics?
A general note of interest: the source of most the energy and moisture that goes into making monster snowstorms is usually many thousands of miles of way, usually based on ocean temps, and it is only the jet stream and atmospheric circulation patterns that bring the storms in for their local effects, so in general, looking at what the local weather is or was prior to the arrival of a monster storm is perhaps statisically interesting, but won’t tell you much about the general heat flux dynamics over the distant oceans that set up your monster snowstorm. Here in Colorado, the moisture one of our most famous blizzards in 1982 with high moisture content was tracked all the way from the sub-tropics near Hawaii and was the result of a larger scale Madden-Julian Oscillation that had nothing at all to do with how warm or cold our local weather had been during the time.
R. Shearer:
We had warm snow in Nova Scotia Monday. Surface temperature was 34.6F but it snowed 5 inches. By the end of the day there was 2-3 inches of water saturated snow on the ground.
I walked the dogs for 35 minutes in the morning and the snow turned to water as it hit me and soaked right through a down winter coat. Warm snow indeed.
January has started out as a warmer than usual month. Today was sunny and 26F: a beautiful mild winter day.
R. Gates says:
January 5, 2011 at 11:03 am
I always read and appreciate your comments, but for this snippet:
“…….Generally, since every GCM predicts an acceleration of the hydrological cycle, and there is global evidence of this occurring, then….”
If you would, please provide a link/citation for the global evidence of an acceleration of the hydrological cycle. Mind you I am not disputing this; I just want to see to see the study/data, as I would consider this to be evidence of a negative feedback climate mechanism. I know this is not fully agreed upon; for example the role clouds play as a net positive or net negative feedback is disputed, and of course clouds (and thunderstorms and other major storms!) are part of the hydrological cycle. But evidence of an acceleration of the hydrological cycle is something I’d be very interested in reviewing.
Thanks!
I agree with
P. Solar says:
January 5, 2011 at 4:57 am
“You analysis shows a correlation between cold in one state and snow in that state, something that ties in with everyone’s experience of weather over our own lifetimes.
As I understand it, the warmist proposition here is that snow is a form of precipitation and that GLOBALLY warmer temps will lead to increased precipitation in affected areas.
Most evaporation takes place over the oceans so that is where the warming is relevant. If conditions in a particular state are such as to cause snowfall this snowfall would be heavier in a warmer world. A warmer world would not mean that for a few days in one location it was now impossible or unlikely that snow producing conditions prevail.”
It seems to me that Dr Keen’s graphs of total winter snowfall versus temperature are not relevant to what Lawrimore says about the impact of global warming according to USA Today.
“If nothing changes, Lawrimore predicts:
•Flooding rains like those in Nashville in May will be more common.
“The atmosphere is able to hold more water as it warms, and greater water content leads to greater downpours,” he says.
• Heavy snow, like the record snows that crippled Baltimore and Washington last winter, is likely to increase because storms are moving north. Also, the Great Lakes aren’t freezing as early or as much. “As cold outbreaks occur, cold air goes over the Great Lakes, picks up moisture and dumps on the Northeast,” he says.”
It seems to me his statement was not about total winter snowfall, but rather about the occurrence of heavy snowfall events. Due to the warming of bodies of water there will be more moisture in the air. If this moist air becomes chilled it makes the snowfall total for an individual precipitation event increase.
The recent snowfall in the Northeast is an example of this phenomenon.
http://www.bloomberg.com/news/2010-12-27/snowstorm-blankets-u-s-east-coast-disrupts-holiday-air-railroad-travel.html
“The city’s Central Park had 20 inches (51 centimeters) of snow by 8 a.m., the most for the month since 1948, the National Weather Service said. Skies cleared over New York by daybreak as the agency issued blizzard warnings for Boston and into Maine.”
The lake effect, which is the second phenomenon he discusses is responsible for the snowfall in cities like Syracuse and Rochester, NY which are further north.
I don’t have any statistics, but the idea that warming of oceans and other bodies of water would lead to an increase in heavy snowfall events seems correct on the basis of basic physics.
I too grew up in the Philadelphia area, and the key thing you must be aware of with regard to snowfall is that Philadelphia is often near the “freeze line” in winter. It can get a lot of cold rain just above the freezing temperature (I hated that as a kid). So it stands to reason that in colder winters more of the winter precipitation would fall as snow instead of rain.
A more complete analysis would look at total precipitation (which means the water content of snow) versus temperature, and percentage of total precipitation that falls as snow versus temperature.
I do agree that those who claim these big east-coast snowfalls are “evidence of” or “consistent with” global warming trends are completely misapplying a concept that has some merit. Yes, it’s true that warmer air can “hold” more water and so has the potential for heavier precipitation. That’s why Antarctica is the driest continent in the world. The IPCC reports predict that Antarctic warming would contribute negatively to sea-level rise, because the resulting increased snowfall over the continent would outweigh any increase in melting at the edges.
It would be interesting to repeat this analysis for locations that virtually never exceed freezing during winter (e.g. Calgary, Minneapolis, Ottawa). For these locations, there may be something to the idea that warmer winters bring more snow (although it could also be such a minor effect that it is overwhelmed by other factors).
But it is absurd to attribute the unusually cold stroms that have been hitting the US east coast these last two winters to “global warming”. This latest one dumped snow as far south as Atlanta. I don’t think they were thinking about global warming there.
R. Gates says:
January 5, 2011 at 12:32 pm
I did not realize you are a neighbor! I’m here in Colorado too, and had just moved here the January prior to the Blizzard of ’82. I will never forget that storm.
Dan
P. Solar says:
January 5, 2011 at 11:54 am
“We are not discussing Lawrimore et al. , we are discussing what you presented in this article.
…Your LOCAL data shows LOCAL cold correlated to LOCAL snow.
…Your LOCAL data does not give any information about the effect of GLOBAL warming on LOCAL snow. In what way do you claim to address the question that you pose as the title here?”
Au contraire, we ARE discussing Lawrimore. My entire post refutes his statement that in a warming world, storms move north and bring more snow to LOCAL places like Philadelphia.
Where did he get this idea? Apparently from GLOBAL models published by the IPCC (see fig-11-8-3 in IPCC AR4), all of which have the LOCAL climate at Philadelphia warming. Some models have the expanding tropics pushing the polar front, polar jet, and storm track farther north. So Lawrimore is talking about a LOCAL effect due to GLOBAL warming predicted by GLOBAL models.
And the predicted LOCAL effect of these GLOBAL models is NOT happening.
R. Gates says:
January 5, 2011 at 12:32 pm
“…the source of most the energy and moisture that goes into making monster snowstorms is usually many thousands of miles of way…
…Here in Colorado, the moisture one of our most famous blizzards in 1982 with high moisture content was tracked all the way from the sub-tropics near Hawaii and was the result of a larger scale Madden-Julian Oscillation that had nothing at all to do with how warm or cold our local weather had been during the time.”
Howdy neighbor! I’ve been enjoying Colorado snow storms for 43 years, and R. Gates is correct that the energy for these storms comes from thousands of miles away in the form of jet streams and vorticity maxima (otherwise we’d be unable to predict them). Many big upslope storms along the Front Range form at the tip of jet-stream-level cirrus plumes that emanate from the tropics, particularly during el Nino (as in the 1982 and 2006 Christmastime storms). But the moisture for these storms is more local, coming from the Gulf of Mexico. Dew points in eastern Colorado during the 1982 blizzard ranged from 19 to 27 F, which is not much different than the dew points today (a sunny day with no snow). What made the blizzard so notable was fronts, divergence, vorticity, and such, all lining up just right. Over the past 40 years, big upslope storms in Colorado have neither increased nor decreased in frequency. Which gets us back to storm tracks, and there’s no evidence that they’re moving north as Lawrimore claims.
Anybody who has forecasted weather for any length of time knows that the majority of major snowstorms occur during “colder” winters. There are exceptions, and the East Coast is a special case. But for the Rockies, the Great Plains, and the Great Lakes, colder winters lead to more snowfall.
In any event, it was just a few years ago that our experts and other Alarmists were warning the world that snowy, frigid winters are fast becoming a thing of the past. And within the next 30 years, most of the Mid-Latitudes would be snow free. Funny how billions of dollars of research theory can turn on a dime.