May 03, 2018

Decreasing Cold Waves: The Most Potent Sign of Global Warming in the Pacific Northwest?

I have spent quite a bit of time dealing with excessive claims regarding current global warming impacts made by the media, politicians, and some activist organizations.  This comes at some personal cost (e.g., folks at the Seattle Stranger start calling me names), but truth is important. 

 But fair-minded folks then ask...are there any signs that anthropogenic global warming is occurring?  The answer is yes, and I have tried to cover them in some previous blogs.

Today I will talk of another one:  the dramatic reduction in very cold days here in the Pacific Northwest.  Days in which Arctic or modified Arctic air moves into the region, bringing temperatures down to 20F and below near sea level in areas of the western Washington.

Let me illustrate by showing you the monthly averaged minimum temperatures averaged over the entire State (Washington, of course) from 1900 to today, using the data from the NOAA/NWS Climate Division data set (see below).

The minimum temperatures during the summer (around 50F) have risen very slowly and steadily during the past 118 years.   But the lowest monthly temperatures, which of course occur mid-winter, are a different story.   Huge differences in time, with much lower monthly minima during the first part of the 20th century compared to recent decades.

Specifically, during the past 25 years, the monthly minima never have gotten below 25F.   Such cold temperatures were common before 1990, with the period before1955 including several months below 20F. 
And this pattern is also true over the Puget Sound lowlands (below) 

and over the Columbia Basin

We simply don't get the severe cold waves anymore, but why?  Time for Northwest cold wave 101 and be prepared to be surprised!

As illustrated in the map below, our super cold waves occur when air from the Arctic moves down into the NW Territories, NW Alberta, across a lower area of the Rockies into the basin of the BC interior, and then through the Fraser and Okanogan Valleys into Washington (and if deep enough across the terrain).

Normally, air reaching Washington comes off the mild Pacific Ocean and thus we don't get cold.   Only when the circulation changes so that we are cut off from the Pacific Ocean and air is pushed southward and across the Rockies and Cascades can the Arctic come to Washington.

What atmospheric pattern does this?  At the surface, this situation is associated with a cold high pressure area to our north and low pressure just south of Puget Sound--like the case  (Nov. 1985) shown below

Another example is shown below, from a day during a supercold stretch in January 1950.

Aloft (e.g., 500 hPa, about 18,000 ft), the classic pattern is a big ridge of high pressure over the eastern Pacific that stretches into Alaska and a sharp trough over the Northwest (see below).

Now that you are trained up on Arctic outbreaks, why would anthropogenic (human-caused) global warming result in fewer strong Arctic outbreaks in Washington?

The first reason is our Arctic connection.  Increasing greenhouse gases preferentially warm the Arctic, something shown by virtually all climate models.   And the warming during the past century parallels this pattern, as shown by the observed temperature change since 1900 (below).

So clearly, if greenhouse gases warm the Arctic, our primo cold waves will be weakened since the Arctic is the source of the cold air.

But there is something else:  the high pressure north of us has not been as extreme (high) during the past several decades and thus is less likely to cause cold air to push into our region.  This is illustrated by a plot of monthly low level (1000 hPa) geopotential height (like sea level pressure) over British Columbia since 1920 (I blocked out the earlier period when there was much less data and thus less reliable).  During the last 30 years B.C. has not gotten above 200, but that happened all the time during earlier decades.

There are two factors contributing to the weakened high pressure extremes.  First, cold air is more dense and tends to cause higher pressure.   But there is something else:  global climate models suggest that the amplitude of large scale weather features will tend to lessen under global warming.  So highs and lows will become weaker in the midlatitudes as the earth warms.  I have done some of this analysis myself with past doctoral student Matt Brewer and this finding is quite robust.

So human-caused global warming is bad for business for cold waves.  A figure from the National Climate Assessment based on observations shows this, displaying the change in coldest temperatures between a contemporary period (1986-2016) and the first 60 years of the 20th century (below).  Washington State has some of the biggest decline in cold waves.  Why?  Because of our Arctic connection.  Same with the upper plains of the U.S.
For these and other reasons, I believe that decreasing cold waves is one of the best indicators we have of human-caused global warming.

Thus, it drives me crazy when some global warming activists, such as Al Gore and ex-presidential science advisor John Holdren, claimed that human caused global warming was increasing cold waves in the U.S. or making cold waves more frequent.  Poor science and in contradiction to observations.

 Why do they purposely deceive the public?  Because they were afraid that some recent (moderate) cold waves might give support to "deniers" and skeptics who "believe" that global warming is nonsense.

Who in the world would do that?  

My take is that scientists and those concerned about the environment should stick to the truth and the best science.  Telling tall tales to neutralize the "fake news" of the other side, will not advance science nor help society deal with environmental problems.  Everyone loses.


  1. Have you compared one iota of data to solar cycles. If not, you are looking at only part of the elephant blind guy.

  2. Cliff: Would the decrease in cold waves be any different if it's natural vs human caused or say 80% natural and 20% human?

  3. I am surprised that you appear to have no knowledge of solar cycles, gas giant cycles and the repeating ice ages that occur every 200 to 400 years. As a weather "expert", you appear to have very little knowledge about GLOBAL COOLING.

  4. Andrew...yes, i have even published in this area. Solar variation can not explain this signal.....I will do a blog in the future talking about this issue...cliff

  5. Not spot on topic, but I have an impression that when forecast high and low temperatures turn out not to be accurate, it seems like the actual temperatures are usually higher than forecast.

    This is likely some kind of confirmation bias on my part.

    However, it occurs to me that the data for actual vs forecast must exist and may be a routine metric.
    If so I would be curious to know what the data say.

    I live in eastern WA.


  6. have looked at solar cycles. Can you tell me how they explain the decline in severe cold waves over the Northwest?..cliff

  7. It's entirely possible to have an increase in cold waves, but at the same time fewer record-breaking cold temperatures (fewer *severe* cold waves). I wouldn't be surprised to see the "warm arctic, cold continent" hypothesis confirmed in the years ahead. The problem is the most dramatic changes in the arctic have only occurred in the past decade or so, so it will take time to validate.


  8. No cold waves anymore? Oh please. Where do we even start?

    Cliff, you're a serious guy and I genuinely admire your willingness to call out the alarmists on their utter craziness. But I don't think you or anyone else has delivered the goods on global warming.

    There are so many angles of attack. As someone who switched viewpoints after doing a lot of research on the issue, what mattered most to me were the following three things:

    1. The predictions made in the 1990s and the first decade of the 2000s have not come true.

    2. The statistics used in the IPCC's modeling are fundamentally flawed, and as a result we've seen academics and gov't agencies actually alter the temperature records.

    3. The AGW believers committed a basic error at the outset by coalescing around a single hypothesis, rather than following T.C. Chamberlain's admonition to consider multiple working hypotheses.

  9. stusual said:

    "I am surprised that you appear to have no knowledge of solar cycles, gas giant cycles and the repeating ice ages that occur every 200 to 400 years. As a weather "expert", you appear to have very little knowledge about GLOBAL COOLING."

    It strikes me as incredibly ironic when people try to sound smart and condescending, but produce basic factual content that is outright incorrect.

    If you're interested in a discussion on the milankovitch cycles (which is what you're hinting towards) then I suggest you come a little more prepared.

    Ice ages do not happen on 200-400 year cycles. They occur on the order of quite literally, million+ year cycles. We are still in fact in an "ice age", known as the Pliocene-Quaternary Glaciation that began ~2.58 millions years ago. Over the past ~12,000 years, we've been enjoying a nice "interglacial period" known as the Holocene. And yes, over the next tens of thousands of years we will see a tip back towards a global cooling trend, as dictated by the Milankovitch Cycles. What impact anthropogenic greenhouse gasses will have on that future glaciation is yet to be determined (obviously).

    Currently, there is no evidence whatsoever in the scientific literature that supports a "Global Cooling" hypothesis any time soon. Every data point in every peer-reviewed climate study very clearly supports Global Warming. If you knew how to read, and had any critical thinking capabilities, you would know this.

    Cliff's facts are not his "opinions". They just that, facts. That is point of science, actually. It is a way of thinking and approaching questions that is specifically designed to eliminate human retards as much as possible. And, in today's political climate, science does a rather nice job of pointing out the truly stupid humans, such as yourself, that really do a brilliant job of bringing down the collective intelligence of our entire specie. Well done.

  10. Fewer extreme cold waves... which, Unfortunately, explains the recent plague of pine beetle attacks that have gone up and down the Rockies. It has to get below -30 F for several days to kill the beetles, and this is becoming rare in the Rockies and interior ranges.

    Let us hope that some other natural control (not fires- woodpeckers maybe?) will come to the rescue of the forests of the West.

  11. Hey Russell,
    Take a deep breath buddy, science is never really settled, if it was think of all of the scientist that would be out of a job. Name calling didn't help in school and its not going to help you in the grown up world.

  12. Intresting! The temperature in the first one and a half million years of the Pleistocene was lower than today's but most of the time higher than 4 degrees below present temperature. Also not caused by man.

  13. The sad practical reality is that the AGW believers, who started out by rather piously instructing everyone not to confuse weather with climate, now seize on every big departure from average -- hot or cold, dry or wet -- as a proof statement.

    Fact is that right here in North America, we have highly variable weather, and we have a very short record of that weather, along with a short record of the climate. The cult-like antics and group-think of the AGW side has badly eroded their credibility with everyone but the most doctrinaire, tribalistic "progressives."

  14. Ansel - many foresters believe that the tons of accumulated dead wood throughout the inter - mountain west and Pacific Northwest have been significant contributors to the spread of the pine beetle. As you've stated, the extreme fire suppression methods enacted over the past six decades have done great harm to the natural cycle.

  15. Russell - all of the peer - reviewed experts at one time were predicting a coming of the next Ice Age. It was stated often, back in the 70's. I remembered reading the MSM articles screaming about that very subject. It's reasonable to be skeptical about anyone who says that "the science is settled." That's why I respect Dr. Mass's opinions on the subject, as well as others such as Dr. Judith Curry and one of the fathers of climatology, Dr. Richard Lindzen.They know enough to know that they don't know enough to make sweeping conclusions.

  16. Hey Russell... and have you read the literature about what helps and doesn't help when conversing with climate skeptics?

    You being condescending (e.g. "If you knew how to read.. had any critical thinking capabilities") and name calling (e.g. "truly stupid humans, such as yourself") is not how to appeal to anyone, much less to anyone who has a very different understanding of a serious situation.

    I'm sure you're frustrated, angry and concerned (or am I projecting my own feelings?.. I just started reading No Immediate Danger yesterday so this could be the case...), but really if you're going to go on what climate scientists say about climate change, please also follow what the social scientists have said on talking about climate change.

  17. Cliff, I believe but can't find where you've addressed the increasing amplitude of the N/S waves in the jet stream due to climate change. How does that tie in to the lessening of mid-latitude highs and lows?

  18. Eric Blair - How do you know that Judith Curry or Richard Lindzen are not making their own "Sweeping generalizations"? We know you believe, but how do you know?

    Our very own shining intellect of Canadian journalism Rex Murphy just argued that a certain selection of experts (the usual suspects) were in his estimation the correct ones. Here is what he said of Judith Curry:

    "How about Dr. Judith Curry, a woman of preeminent credentials, exquisite manners, and a specialist in this very field – whose argued reservations about the “science,” scrupulous attention to quality research, and humility in the face of the overwhelming rigours of the scientific method, makes her a singular voice in our contentious time."

    All reasonably true but exactly how does that qualify her as "a singular voice in our contentious time" that is correct?

    For all old Rex Murphy knows about climate science (not a lot, having long dropped out from Oxford) her "singular voice" is nothing at all to be proud of, along with all the other singular voices.

    For Murphy, an incompetent, to select a hand full of contrarians as correct while the vast majority of their peers, all entirely possessing the same qualities (including "exquisite manners" as if that matters, but excluding one quality - a singular voice) is no different than any Anti Vaxer selecting the wise words of Andrew Wakefield over the whole of professional health research based on:

    "preeminent credentials, exquisite manners, and a specialist in this very field – whose argued reservations about the “science,” scrupulous attention to quality research, and humility in the face of the overwhelming rigours of the scientific method, makes her a singular voice in our contentious time."

    So what? An incompetent cannot judge. Rex Murphy does not possess the required skills. Here is the definition of an incompetent:

    not having or showing the necessary skills to do something successfully.

    Now Rex Murphy will say otherwise. He will say "but I do have and show the skills - look, the proof is in who I pick"

    Even if decades from now Rex Murphy is proven correct, that they are right and all the others are wrong, it still isn't skill.

    It is random roll of the dice. It is luck, not skill. Even then he remains an incompetent, just a lucky one!

  19. Bruce Kay recently come on here to defend an individual convicted of defrauding a public institution of hundreds of thousands of dollars, after the scumbag came on here to attempt to refute one of Dr. Mass's posts. Why would he do such a despicable thing? Because he agreed with the fraudster's points - pretty much says it all regarding his character and credibility. Beneath contempt.

  20. Excellent post Cliff. This gets back to a long time assertion of Lindzen, viz., that with warming the equator to pole temperature gradient lessens and thus midlatitude weather will become less extreme. It sounds like your research confirms that.

  21. Bruce Kay, did you take an extra arrogance pill before you wrote that?

  22. Placeholder,

    THE reality is that you don't KNOW any more than your contenders do the true effect of human-produced "greenhouse" gas emissions on Earth's climate system. Fact is, there isn't a second, identical solar system containing a second Earth, identical in every way but for being completely undeveloped and unpopulated by humans or another analogous species, for us to run a comparison with.

    So, how about stowing the scoff and showing a little deference to Dr. Mass' authority as an expert in his field? That is unless you also happen to be similarly credentialed - something I rather doubt given your cryptic handle. If you've something to hide perhaps you ought not to be scribbling banal commentary on a highly public blog...

  23. Wow so much excitement.. IHMO (yes I repeat myself). Pumping up hydrocarbons sequesterd during one one of Earth's warm periods, means we are warming the atmosphere, with that carbon...
    Period.. who wants to argue this????..........

    Is the warming even IMHO no, mater of fact it looks like warm artic cold continent may be realistic. Fact is no body has been very accurate on this subject.

    Personally, I very much enjoyed Cliffs data on less cold extreams, which is not a new concept if you follow the USDA climate zone map revisions, which have been pointing in the direction of less low minimums for decades now.

    Imho, the low minimums, is a spot on indicator... Pine bark beatles, sorry poor forestry habits. All the tree huggers saving crappy second and third growth forests, that are garbage. They are NOT the original old growth forests that we're cut 100 plus years ago.

  24. true Blue - all I said was what the best known science says about human judgement.

    If the best known science is "arrogant", then what pray tell is those who reject it?

  25. Stephen Murdock, are you seriously suggesting that you'd have more regard for my opinion if I attached a name? Where is your scolding of the others here who happen to be in your cult but also use monikers? What is it about Seattle "progressives" that make your kind such a bunch of condescending, sanctimonious hypocrites? Is it any wonder that the general public does nothing more than pay lip service to your hysteria?

  26. Well Placeholder, Your buddy Eric places quite a bit of credibility to names such as Lindzen and Curry while discounting credibility for other names such as Mann or Weaver, none of which he has the skill to tell the difference.

    So one might ask, with considerable justification:

    What is it about back woods "Regressive's" that make your kind such a bunch of condescending, sanctimonious hypocrites? Is it any wonder the general public does nothing more than pay lip service to your hysteria?

    But seriously, we know there are legitimate reasons to remain anonymous, social and economic retribution or ostracization being the primary ones. You no doubt have your reasons but you must also recognize that if you are willing to say such character assassinating things about people, anonymity sure makes that job an unaccountable one!

    Doesn't it?

  27. Bruce Kay has not only defended a criminal on this blog, but has also commented repeatedly regarding the policies and culture of the US, despite being from another country. He hasn't paid any taxes in the US, nor has he ever voted in any elections - yet he still makes sweeping judgements and generalizations on a country of which he has no stake in, and no affinity or ties to whatsoever.

  28. Get your subtropical plants in the ground already! USDA Zone 9a is here (Seattle). A large array of semi-tender succulents can winter outdoors in our warmer winters including graptopetalum, dudleya farinosa, the "cold hardy" echeveria types including "neon breakers" and echeveria agavoides.

  29. Sempervirens206!!

    Yep, bring on all plants you always wished you could grow...

    Arbor day has a neat animation where you can see the minimum lows march forth, from 1990 to 2006
    Species move north or go extinct.

    Wether we are doomed or not, one might as well enjoy planting some 9a plants while we can!

  30. Bruce, isn't it about time to turn your energies to fixing Canuckistan? You can start with that ski bum/prime minister. He is actually an accurate representation of your laughable playpen, but sometimes accuracy is a problem.

  31. Enough is enough.

    Someone from Canada has every right to voice on opinion here as does someone from California...

    Matter of fact BC Canada is closer, and can anticipate similar climate effects as us in Washington.

    Besides, climate and emmissions are a Global thing.. ya???

    Needs global cooperation....

  32. Organic Farmer - fair point, but it's beyond tiresome to listen to those opining endlessly about the US when they have no actual skin in the game. Either put up and spend your money or shut your piehole. Not to mention the reprehensible act of defending a criminal - that's so beyond the pale it boggles the mind.

  33. sorry to pop your bubble Eric but my documented record, despite your repeated claims otherwise, shows that i do not defend his criminality. in fact i say that he should face the consequences, as he did.

    What i did defend was his motive in breaking the law which was to disclose what the Heritage Foundation would not. Right now as we speak protestors are breaking the law and getting arrested in Burnaby BC. They do so willing and expect nothing but what the law will dish out. That is called civil disobedience.

    Something you'd think any American freedom or die libertarian could have some empathy for.

    Other than that, as Organic Farmer plainly pointed out, we all have skin in this game, even the American one where you like us have a grossly overboard per capita carbon footprint. Rest assured we are duking it out this side of the border too but proportionally, the Americans need to step up, if they still want to be considered the leaders of the free world.

    And if your carry that title, you can expect criticism for it when justified, just as much as accolades, when justified.

    Or do you honestly think you deserve only the accolades?

  34. Last truly cold spell I remember was 90-91? Legit cold. Single digits. I loved that week.
    Not much since then. Could be I'm just not recalling other significant cold snaps.
    OTOH the East Coast keeps getting slammed by polar weather. Not easy to break cold records there, but they've done it.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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