Are US winters cooling or warming? It is all so very confusing at WUWT....

It wasn't that long ago that WUWT-ers were being warned that the world is heading for an ice age.  The "ice age cometh-ers" to varying degrees include:

• David "funny sunny" Archibald
• Tony "central England" Brown
• Ed "ice age cometh" Hoskins
• Denier Don Easterbrook

The one thing you can say about those WUWT contributors is that they are prepared to make a prediction, even though their predictions are laughable.  Most of the people at WUWT just scoff at science but aren't prepared to stick their neck out.  I've yet to see Anthony Watts make any prediction.  Wondering Willis once made a guess that the world is about to get cooler.  Perennially Puzzled Bob Tisdale, when pinned down, doesn't want to make any predictions.  He's too busy keeping track of bits of the ocean in the hope that some bits haven't warmed as much lately (so that he can put up a chart of a patch of sea and say that global warming isn't happening, or it's not happening in that bit of the globe).

It was freezing cold in the USA this winter, but it's not unusual?

Over the past few months, there have been a myriad of WUWT articles about just how cold it was this winter in the USA.  If there was a WUWT article about the record hot Californian winter, I must have missed it. Which is odd, since that's where Anthony Watts, the blog owner, hails from. Here are just some of the articles about how cold it was in the USA this past winter:

• Over 2000 cold and snow records set in the USA this past week - 13 December 2013
• New record low set in the coldest city in the continental USA – much of the country headed for a deep freeze - 2 January 2014
• USA cold weather records outnumber warm records 6 to 1 - 8 January 2014
• NOAA: US Cold records outnumber warm records 66 to 1 in the last 7 days - 8 March 2014
• Satellite Animation Shows Massive Eastern U.S. Cool Down - 13 March 2014
• Coldest U.S. winter in a century - 26 March 2014
• It’s official – Chicago experienced the coldest four months ever on record - 1 April 2014
• NASA on ‘the big chill’ this winter: ‘In some places temperatures were 40°F colder than average’ - 7 April 2014
• and more in the same vein.

However in an apparent about-face, today the headlines at WUWT are (archived here):

Holdren Is Wrong – Cold Winters Are Not Getting More Common

Paul Homewood, who wrote the article even put up a chart to prove that US winters aren't getting any colder.  In fact looking at the chart, since the 1980s winters in the USA have become a whole lot warmer:

Source: NOAA via WUWT

Paul injects a bit of reality at WUWT and writes:

Clearly, on a national basis, recent winters have not been unusually cold. In the last 10 years, only three winters have been colder than the 1901-2000 mean. Moreover, no winters in recent years have come anywhere near to being as cold as some of the winters in the 1970’s, for instance, or earlier.

Paul goes on to look to see how much of the USA had extreme winters.  Using his method, he confirmed that the 1970s was the last decade notable for cold extremes across the largest portion of contiguous USA.  He wrote that it's clear that much less of the country was affected by cold compared to the twentieth century:

It is abundantly clear that much less of the country has been affected by extreme cold this winter, and indeed other recent ones, when compared with the 20thC. There is also no trend towards cold winters becoming more common.

Then Paul remembers who he's writing for.  So he figures he'd better cover himself for the global warming deniers and say that mild winters aren't "taking over" either, writing:

What is also interesting is that there does not seem to be much of a trend towards milder winters taking over. Only the winter of 2011/12 stands out in this respect, and there have been plenty of similar years previously.

Yet if you look at the first chart he posted (above), it's pretty obvious even to the naked eye that in the last few decades, the average winter time temperature is much warmer than it was in the past. Even looking at his own charts of extremes, he should have recognised that there is a lot more red area than blue area in recent decades.  Here are the two charts Paul put up, showing extremes in minimum and extremes in maximum temperatures for winter, with my animations (click to enlarge):

Adapted from source: WUWT

So is it warming, cooling or doing neither? Anthony's readers must sometimes be scratching their head wondering whether to believe what they read at WUWT or whether to believe what they read at WUWT.

John Holdren and Jennifer Francis' Polar Vortex

John Holdren's statement, which Paul Homewood was countering, was from a video in which he discusses the polar vortex.

Paul quotes the following bits of text.  He doesn't link directly to where he got the quotes.  The first bit of text is from the above video (at 0:32), which Paul doesn't repost, and the second paragraph is taken from a White House web page :

“A growing body of evidence suggests that the kind of extreme cold being experienced by much of the United States as we speak is a pattern that we can expect to see with increasing frequency as global warming continues….

We also know that this week’s cold spell is of a type there’s reason to believe may become more frequent in a world that’s getting warmer, on average, because of greenhouse-gas pollution.”

 The video is short, so I'll copy the text here so you can read John Holdren's quote in context:

If you've been hearing that extreme cold spells like the one that we're having in the United States now disprove global warming, don't believe it. The fact is that no single weather episode can either prove or disprove global climate change.

Climate is the pattern of weather that we observe geographically and over the seasons, and it's described in terms of averages, variations, and probabilities. But a growing body of evidence suggests that the kind of extreme cold being experienced by much of the United States as we speak is a pattern that we can expect to see with increasing frequency as global warming continues. And the reason is this: in the warming world that we're experiencing, the far north, the Arctic, is warming roughly twice as rapidly as the mid-latitudes, such as the United States. That means that the temperature difference between the Arctic and the mid-latitudes is shrinking, and that temperature difference is what drives what is called the circumpolar vortex, which is the great counterclockwise-swirling mass of cold air that hovers over the Arctic. As the temperature difference between the Arctic and the mid-latitudes declines, the polar vortex weakens, and it becomes wavier. The waviness means that there can be increased, larger excursions of cold air southward -- that is, into the mid-latitudes -- and, in the other phase of the wave, increased excursions of relatively warmer mid-latitude air into the far north. 

Computer models tell us that there are many different factors influencing these patterns. And, as in all science, there will be continuing debate about exactly what is happening. But I believe the odds are that we can expect, as a result of global warming, to see more of this pattern of extreme cold in the mid-latitudes and some extreme warm in the far north.

Essentially, what John Holdren is describing is the hypothesis put forward by Jennifer Francis and Stephen Vavrus in a paper in GRL in 2012.  As John Holdren says, "there will be continuing debate about exactly what is happening".  Indeed the Francis hypothesis is the subject of ongoing debate.  Some scientists, such as Kevin Trenberth, disagree quite strongly. Others are more circumspect and are entertaining the idea that the hypothesis has merit.

Coincidentally, there is an article in the current issue of Science about this very topic, titled "Into the Maelstrom" and written by Eli Kintisch.  If you can get hold of a copy it's worth a read (at least I found it very interesting and informative).  Eli Kintisch says that Jennifer Francis has modified part of her hypothesis in the light of a paper by Elizabeth Barnes, backing off from the notion that "a curvier jet stream is leading to more atmospheric "blocking"". Here's an excerpt of the Science article:

The most vociferous critiques, however, have come from researchers who study atmospheric dynamics, or the many mechanisms that jostle and shape air masses. Given the Arctic's relatively puny influence over the planet's atmospheric energy flows, the notion that it can alter the jet stream "is just plain wrong," says dynamicist Kevin Trenberth of the National Center for Atmospheric Research in Boulder. The more likely culprit, he says, is natural variability driven by the tropics, where Earth gets its largest input of solar energy.

Such variability, Trenberth says, could explain the jet stream's giant curvy shape this past January, which brought record chill to the southeastern United States, warm temperatures to Alaska, and made "polar vortex" a household term. At the time, a massive amount of so-called latent heat was accumulating in the tropical Pacific, Trenberth notes, in an incipient El Niño event. Parcels of warm air from the tropics may have forced the jet stream northward in one place, causing it to meander southward farther east. "It may not be that Arctic amplification is causing a wavier jet stream, it may be that a wavier jet stream is causing Arctic amplification," he says.

"I understand that people would be skeptical," Francis says. "It's a new paradigm." But she counsels patience. She notes that evidence of Arctic amplification itself has emerged from the statistical noise only in the last 15 or so years, so it may take time for the changes to the jet stream to become statistically significant. And she believes the modeling experiments that fail to simulate a more meandering jet stream are biased, because they don't include sufficiently robust Arctic amplification.

Such arguments have persuaded some colleagues to at least wait and see. Oceanographer James Overland of NOAA's Pacific Marine Environmental Laboratory in Seattle, Washington, for example, says, "I find the tropical explanation for the recent behavior of the jet stream no less implausible than the Arctic one." And he suspects that, as data accumulate, the dynamicists will come to gain a greater appreciation for the Arctic's role.

Paul Homewood's Strawman

I think it's worth pointing out that Paul Homewood's article is one big strawman.  He is trying to refute something that John Holdren didn't say.

Paul is arguing that because the winters on average or over much of the USA aren't the coldest compared to the entire record of winters then John Holdren is wrong.  But John Holdren was talking about cold spells not average winter temperatures.  He was talking about periods when parts of the USA may experience extremely cold weather.  Also, in my view the winter extremes need to be considered in comparison with a rising global surface temperature.  What this would mean is that cold extremes would be getting warmer over time, as global surface temperatures rise.  Yet there can still be extreme cold across parts of the USA, just not as extreme as the coldest in the instrumental record.  Perhaps in several decades from now, an extreme cold spell will be as warm as a current mild winter in the USA, yet it may still be caused by a "wavy" polar vortex.  (A mild winter may well be as warm as a mild spring or even a mild summer in the future.)

From the WUWT comments

Let's see how the WUWT-ers reacted to Paul arguing that US winters aren't getting colder and writing that "There has been nothing unusual or unprecedented about this winter."  They are all over the place.  Some of them are saying winters are warmer. Others are arguing winters are colder. Many of them seem to think the USA is the whole globe. For example: more soylent green! says:

April 18, 2014 at 12:50 pm
“As global warming continues?” Do you think Holdren means “when (or if) global warming continues” because it ain’t warmed in nearly 2 decades.
A technical question — If global warming causes colder winters, at what point does global warming become global cooling? Or does it all just average out? If it all just averages out, does that mean the earth doesn’t have a fever anymore?

phlogiston is trying to work it all out and says:

April 18, 2014 at 1:38 pm
So let me get this straight:
The scientific adviser to the POTUS
is saying that
global warming
is causing colder winters

TonyG isn't giving up easily and says:

April 18, 2014 at 10:53 am
Over a year ago, I saw a program on NGC that suggested AGW could cause another ice age. I guess cold winters would be much more common with glaciation.

pokerguy is deeply depressed and says:

April 18, 2014 at 11:23 am
There was a time when I believed that people in highly positions….at least in a democracy….could not just make things up without paying a price. Now the scales have fallen from my eyes. You can say anything you want for the most part and get away with it. Holdren has been making ridiculous claims without being exposed as a serial liar in the MSM for a long time. Ditto Obama. I don’t think it was more than a year ago when the President of the U.S. simply made up his own facts about global warming by asserting that the globe was heating up even faster than the experts had predicted….which of course is utterly false. In fact there’s arguably been no warming at all for over 17 years.

Deeply, deeply depressing. 

Magma picks up an inconsistency and says:

April 18, 2014 at 11:39 am
Holdren says “cold spells”. Homewood shows Dec-Feb averages.
There is a difference. 

Richard Day likes question marks and says:

April 18, 2014 at 11:48 am
So extreme cold is the result of global warming?
Is there ANYTHING global warming can’t do?????? 

herkimer isn't the only one who says it's been cooling since 1998 (now that year rings a bell) (excerpt):

April 18, 2014 at 11:58 am
Winters in Contiguous US have been getting cooler for 17 winters or since 1998 , but certainly not for the reasons that Holdren states. This recent decline in US winter temperatures is similar to the cooler US winter cycles of 1895-1920 and again 1954-1979 and is due to ocean cycles. 

Rud Istvan gets everything topsy turvey and says:

April 18, 2014 at 12:20 pm
Holden even recently lied to Congress about previous testimony on US drought by Roger Pielke Jr. When Pielke asked for a retraction and apology, he got a six page White House memo citing one paper. Apparently they cannot read either, because that paper (by Trenberth) also supported the Pielke testimony. Which was simply thatnitmisnot possible to make a connection between drought and climate change, per the IPCC SREX and other papers. It is possible to make regional US connections with PDO and AMO.

Why did Holdren try to trash Pielke’s testimony? Because Obama is using the California problem to pump for his climate agenda. Just when you think they cannot stoop lower, they do.

No, Rud, that's not why John Holdren had a go at Roger Pielke Jr's testimony.  This is.


Rob is seeing warmer winters and says:

April 18, 2014 at 2:48 pm
Winters have gotten much less severe
here along the Gulf Coast since the terrible cold decades of the 1980′s and 1960′s.
Holdren’s “speculation” is NOT Science. Not even close.

HenryP says, I'm not sure what:

April 18, 2014 at 3:19 pm
@DirkH
As we are cooling from the top, the higher latitudes get drier and the lower latitudes get wetter.
That is physics.
Locally, at some places, due to the drier conditions, it can get hotter,
paradoxically
perhaps 

Bart says:

April 18, 2014 at 6:52 pm
Seems I recall that last year’s warmer-than-usual winter was supposed to be the harbinger of things to come.

bushbunny is firmly in the global cooling camp and disagrees with Paul Homewood (but doesn't come right out and say so):

April 18, 2014 at 8:08 pm
Of course the government would announce this nonsense to uphold their beliefs, and not face the fact Northern America and Canada would suffer most from extra cold winters. I hope that you don’t experience any more extra cold winters for your health mainly and productivity. Your government should take measures now not to rely on the global warming scare but global cooling that will prove a lot more expensive in the long run to adapt to. 

---

Eli Kintisch, "Into the Maelstrom", Science 18 April 2014: Vol. 344 no. 6181 pp. 250-253 DOI: 10.1126/science.344.6181.250

Francis, Jennifer A., and Stephen J. Vavrus. "Evidence linking Arctic amplification to extreme weather in mid‐latitudes." Geophysical Research Letters 39.6 (2012). doi:10.1029/2012GL051000,

Barnes, Elizabeth A. "Revisiting the evidence linking Arctic amplification to extreme weather in midlatitudes." Geophysical Research Letters 40.17 (2013): 4734-4739. doi:10.1002/grl.50880