August 09, 2009

Was the heat wave a sign of global warming?

Quite a few have emailed me asking whether last week's heat wave was a sign of global warming. Others have suggested that I have been strangely silent on this issue.

Anything, although I have commented on this subject in my blog and KUOW, let me give you my take on this--and I think the take of most meteorologists.

One heat wave, one storm, one event says nothing about global warming or its effects. That is why those who jumped on Hurricane Katrina as proof of global warming were really off-base.

First, this last hot event was completely localized...while we had record breaking heat, the upper plains and midwest (and parts of the east coast) had record breaking cold. The reason: a persistent ridge of high pressure over the western U.S. and a trough over the central/eastern U.S.-- NOT uniform warming. When I went back east for a meeting, people were complaining about the cold, and those of conservative bent were griping about the global-warming fanatics.

Second, one event does not provide much information on trends, and trends are what count in climate. The atmosphere has a certain amount of natural variability, and there will be records and extremes even if the large-scale situation remains the same. The atmosphere is rarely "normal" and the averages include extremes of both directions.

The media and some climate-action groups are continuously confusing the differences between weather and climate and some of their claims are unsupportable --like the frequently stated prediction that the NW will have more windstorms under global warming. There is NOTHING to support this conjecture. I have even heard some explain the unusual cold/snow wave last December on global warming! (the claim is that global warming will produce more weather variability). And another one is about heavy rain events--that our recent heavy rains/flooding are due to global warming. The truth is that heavy rain events are decreasing in Oregon and increasing over parts of NW Washington (I have a student working on this issue). Why would global warming produce such a dipole effect? (I can speculate on this but won't here).

Don't get me wrong...I am absolutely convinced that global warming is going to happen and will be significant here, but many of the claims about local effects are without support. And because we are downstream of the cool NE Pacific, the Pacific NW may see global warming's effects delayed and weakened.

The bottom line of global warming is that the effects will not be uniform, and that the differences will be profound. And there is much about local effects that we don't know. The whole topic has also gotten too political...with some believing that global warming is some left wing/Gore induced dementia, while others hyping its effects to induce a social/economic transformation or to enhance their political prospects.

I suspect mankind will not act fast enough to reduce fossil fuel use to stop large global warming effects and that we will learn to live with it. But that is another topic...


  1. Thanks for this, Cliff. I think people's confusion about local weather short-term vs. long-term global warming is very similar to the way people can easily be confused about statistics in general.

    Good explanation and very helpful. I too think global warming is real, largely human caused, and inevitable now. Hope we're clever enough to figure out how to deal with the mess we've made!

  2. Down here is Lewis County there is mostly scepticism or denial regarding global warming. At the same time most of our historic floods have occurred in the last 35 years, with the worst ones bunched more recently. It is assumed that we will have another bad flood in nearish future. Somehow the trajectory of worse and worse floods strikes me as a sign of climate change, likely connected to global changes.

  3. RLL--but what does the reduction of heavy rain/floods in Oregon tell you about climate change?

  4. Can we take the accelerated melting of the polar ice cap, which has been going on for some years now, as an example of climate rather than merely weather. There are days in Seattle (today for instance) where I look outside and think, maybe global warming wouldn't be all bad. On I global scale, though, I'm worried.

  5. Rich,
    Yes, a SUSTAINED thinning and melting of the arctic ice cap should be the first sign of global warming...cliff

  6. weather vs climate ... one of the 1st and most misunderstood thingsI learned in Meteorology 101 some 25 years ago!

  7. One of the perplexing aspects of the whole global warming policy debate is what level of evidence we need to justify taking action. If we wait until we have incontrovertible proof that human caused global warming is taking place, then it's almost certainly too late to do anything about it. Your post seems to suggest that this is what will probably happen, and you may be right. Sucks for the Maldives, but maybe a good time to buy property in Alaska. The trick will be figuring how far above current sea level to go so my children's children can have water front homes.

  8. Thanks for the clarification, Cliff. To help people understand the difference between climate and weather, I've started making the analogy between the economy as a whole and what's in your wallet today. That seems to help.

  9. Cliff,

    You are pretty easy on the delay and deny crowd who spend a lot of time hyping any abnormal cold event as evidence against man made global warming.

    I have seen few, if any, climate scientists hyping individual weather events as evidence of global warming. This seems to be a media specialty.

    Are you implying above that we haven't yet seen a sustained loss of ice volume and area in the Arctic?

    It seems to me that glacier decline, Arctic ice loss and countless phenological changes provide an compelling set of data integrating the increase of energy in the worldwide climate system.

    Maybe the recent heatwave can be viewed as a sample of what the future might hold on a routine basis here in a Northwest summer.

    With a weather station on Copalis Beach in the middle of the blind spot!

  10. Paul..there has been a loss of volume in the arctic ice sheet that is consistent with global warming expectations. Glaciers have declined, some of that started before it could have been caused by human-added greenhouse gases, but it is quite possible that human-caused warming could have contributed during the last several decades. You should not see the current heat wave as a sign of the future, but clearly there will be more 100F days when global warming really hits here after 2050. And I hate to admit, there IS some hyping going on in my community..but that is another story.

  11. Cliff,

    I'd like to hear some more about that "other story". How about a blog post?


  12. Cliff,

    you said "global warming is going to happen". Global warming has been happening for centuries and even before mankind. Correct? What about the melting of the ice caps and melting glaciers that have been shrinking over the last hundred thousand years or so. Has`nt this been linked to global warming in the news lately? It`s only now in the last several years that the topic of global warming has become more recently talked about, that the media is linking 'this & that' to global warming.

  13. The science-based arguments for a more rational approach to global warming and climate change can be summarized as follows:

    * The Earth's climate always has changed, with cycles of both warming and cooling, long before humans were a factor. The cycle lengths range from decades, to the 1,500-year cycle discovered in Greenland ice cores, to the 17 ice ages that dominated the past 2 million years.

    * The NIPCC report presents solid evidence that any man-made global warming to date has been insignificant in comparison with these natural climate cycles. By contrast, the IPCC has no real evidence to support their claim of anthropogenic global warming.

    * While recent man-made increases in atmospheric carbon dioxide may, in principle, make some contribution to temperature rise, the linkages assumed in order to predict significant future global warming are not proven.

    * Contrary to the computer simulations of climate models, temperatures have not risen over the last decade — despite a continuing rise in CO2 levels.

    * Other factors, such as variable solar activity, solar wind, and cosmic rays, all seem to have a more significant impact on the earth's climate.

    * Panicky reactions to exaggerated scenarios of global warming are bound to be costly and do great damage to world economic development.

    * Adaptation, not mitigation, is a more appropriate response to climate change — particularly for poorer countries.

  14. Mark..there are some technical errors in your comments I am afraid. For example, the fact that it hasn't warmed in the last decade is NOT inconsistent with our numerical models of climate. The linkages of increased greenhouse gases to future warming are completely solid.

    One thing we can agree on is that adaption is very important. ..cliff

  15. CO2 data from

    1998 365
    1999 367.97
    2000 369.07
    2001 370.47
    2002 372.38
    2003 374.92
    2004 377.03
    2005 378.43
    2006 381.36
    2007 382.91
    2008 385.38

    Yet every temp curve is flat or down.

    If anybody has numerical data showing a clear correlation between CO2 and global temps, I'd sure like to see it. I'd like to get an excel spreadsheet with years in column A and temperatures in other columns. I can find plenty of political articles talking about "consensus" but numerical data seems pretty scarce.

  16. Cliff

    What is an example of a trend that would cause us to revise our "consensus" view on man made global warming. What I hear you saying is that the models are solid up to now so we should believe them. So what sort of sustained deviation would have to take place for you to say the models are wrong?



  17. Make sure you properly differentiate between Global Warming and Global Climate Change. They are not the same thing and I think that in many areas of your great analysis your used Global Warming where you should have had Global Climate Change. Warming refers to an increase in the average global temperature over time (which is occuring Mark, it is just a very small change like 0.7C over 70 years, but in a global scale, small changes produce big effects. Look for this value to have an exponential rise over the next century). Climate Change refers to a change in the overall climate, warm or cold, drought or snow, etc. Just a stickler for the details.....

  18. Humans are mobile, capable of intelligence, and fairly adaptable. I'm not too worried about the human species. The flora and fauna of our world, however, are a bit more deeply rooted to the ecosystems in which they evolved. The extinctions we humans are causing are what we should be most worried about.

  19. Incinerating petro-chemicals in internal combustion engines creates some fairly unhealthy air, which we breath. So, even if global warming/catastrophic climate change IS a hoax, switching our transportation and energy production grid from fossil fuels will create a healthier environment, which should be enough reason to continue to work towards carbon neutral energy.

    This doesn't even begin to address the socio/political issues we face by continuing to draw our primary energy source from regions of the world where they really don't like us Westerners.

    Let's not follow the same path we have recently taken with stem-cell research. America was once on the forefront of scientific and technological innovation and this is another area where, if we take the lead, we will continue to be the economic powerhouse we all grew up with.

    Continue to deny, and we continue to fall behind.

  20. Beyond thanking Cliff for a very lucid, much needed, explanation of the relevance of the old adage that "une hirondelle ne fait pas le printemps" (literally, "one swallow doesn't make the spring", but more idiomatically, just because you've seen a robin, don't believe spring is here), I'd like to make two strong points.

    The first has to do with the nature of scientific endeavors. A good scientist loves "changing the paradigm"--finding a novel way to look at things that makes the former way seem primitive by comparison. In climate research, any scientist who today could put forth a credible case, holding up under peer review, that humankind is NOT rapidly altering the planet's climate would thereby establish her career for a lifetime. Key phrase: a CREDIBLE case.

    Second point: if you're going to draw a conclusion, however tentative, you MUST use a model. A model, in most uses of the word, is a representation in mathematical equations of the processes (such as laws of physics) that determine how things change over time. With respect to how things change over time, the most common blunder made by people, however well educated, is to ignore the need for the model, and to rely on simple correlations between measurements taken serially (over a span of time) rather than cross-sectionally (such as public opinion polling). (The Statistics 101 example of such a mistake is the classic case of serial data showing that storks bring babies. Either Google "stork Oldenburg" or read if this is not a familiar example.)

    Throughout my long lifetime it has been well understood that, since the late nineteenth centuries, world temperatures have been rising (although not so rapidly as in recent decades), CO2 levels have been on the increase (again, not so rapidly in earlier years), and that CO2 is an important greenhouse gas (so that an increase in CO2 MIGHT cause an increase in temperature). These three facts don't come close to justifying a claim that mankind is raising world temperature, just as a correlation between the last ten years of world temperature and the last ten years of atmospheric CO2 levels establishes nothing of interest. You gotta do the modeling!

    It was my very good fortune a few years ago to be able to attend UW lectures for an elementary undergraduate course on climate. ("Elementary" does not mean getting through a science requirement with minimal effort; students in the course had to have a thorough command of high school physics, chemistry, and calculus.) Although merely an overview of a complex subject, the course made it clear how solar and terrestrial radiation are mediated by atmospheric phenomena, and also presented the evidence by which the climate of the distant past can be reliably inferred. Factors other than man-made CO2 were most definitely assessed! You GOTTA do the modeling!

    If you have an original insight into climate change, I'm sure the IPCC would like to hear about it. If all you have is a correlation coefficient between time series, no one should have to hear about it.

  21. Saying "We need to do 'X' but we should use reason 'Y' to convince others" doesn't seem to be science.

    If not polluting with hydrocarbons is good, then argue that.

  22. Mark showed a recent time series of CO2 amounts and suggested that because global temperatures have not risen in the last decade, that human-induced global warming is not evident and implicitly not a future problem. But such a conclusion would not be valid. But many, many others share his concern.

    The key thing to keep in mind is that there is a certain amount of internal variability in the system on various time can think of it as noise. Also, the human global warming signal is now relatively small, but will increase exponentially in time. So the superposition of noise and a weak upward signal will inevitably result in short periods of years to decades when the temp could remain constant or drop...especially when the greenhouse signal is weak. Eventually, the greenhouse gas signal will overwhelm the noise (interval variability) and the warming will become obvious and evident. It is only a matter of time before this happens because the greenhouse effects of the gases we are added are so profound and well understood.

  23. Thanks Cliff. Very good explanation. From a perspective on the fire ground I have seen some changes. Whether or not it is from Global Climate Change remains to be seen. For example, many more seasonal wild fire stations in California are now open all year round. Since 1960 there has been a upward trend on acreage burned during a given fire season, even though there has been a huge increase of resources used to fight these fires. Now there are many factors involved here including putting out fires which only increase fuel loading for future fire starts.

    What fire managers are scratching there heads at is the inconsistency of fire conditions over a given fire season. It used to be that all area centers would have some sort of fire regime in place for a summer. Now there are widely differences across the west. One area could be burning like a blow torch and another shrouded in cool moist weather. Predictions are becoming harder to handle.
    Global warming?

  24. Re: Global Climate change and human mobility.

    Not all soil is created equal. An excellent book by a local UW professor "DIRT, erosion of civilizations" will explain much of it, but the short is that the center of the US where we have a huge amount of crops growing cannot be easily replaced by moving North to Canada. The dirt is just not the same stuff and that's as important as the annual rainfall and sunshine.

    Also, it's not just mankind's use of fossil fuel that will tip the scales on climate change. A slight warming that melts the permafrost in the arctic will release a lot of Methane gas which will also cause major warming issue.

    Besides all of the climate issues, it's just a mis use of resources to burn something that took millions of years to produce in a couple of centuries. We may in the future want to use oil for other things that we can't easily replicate in other ways.

    And to top it off, we're giving money to people who hate us.. seems the dumbest idea yet whatever your view on climate change is.

  25. On May 22, I was part of a large group attending the EPA hearings on Global Climate Disruption and the possible health risks involved.

    That's where I heard Dr Evan Kanter, MD, PhD, say the following:

    "Today’s hearing considers the EPA’s finding that 'greenhouse gases in the atmosphere endanger the public health and welfare of current and future generations.'

    "As National President of Physicians for Social Responsibility, I represent thousands of health professionals and we speak with urgency and conviction in support of this finding. The science is clear and we must act immediately to limit the potentially catastrophic impacts of global warming. It is unconscionable to continue on the present course.


    "The World Health Organization estimates that global warming is already responsible for 150,000 deaths and 5 million illnesses each year. These come in the form of malnutrition, diarrhea, and mosquito-borne diseases like malaria and dengue fever. So far the impact has occurred predominantly in poor countries, but the health effects are also evident here in the developed world and will be increasingly felt if we do not take action."

    Dr. Kanter is President of this Nobel Peace Prize organization. How those health impacts occur are given in his full remarks at

    If you read nothing else, please consider the W.H.O. estimate of 150,000 deaths each year due to climate impacts -- mainly in poorer countries -- so far!

    And then consider the repeated comment in these blogs about people in other parts of the world "who hate us". (Then buy Real Change this August 12 [pg 2] for a fuller understanding of why that might be.)

  26. I'm just curious--because of media hype--what is the effect of melting arctic ice on our weather patterns here? Remember the movie "Day After Tomorrow" (terrible, I know). But is there any validity to how the cold water flooding into the warm currents changes our weather? Would love to know your thoughts on this.

  27. Laurel,
    That "day after tomorrow" movie showing an ice age being produced by global warming is at odds with what we know about the effects of the upcoming warming...cliff

  28. Cliff, aren't there concerns about shutdown of the global conveyor based on decreased salinity in the North Atlantic from melts in Greenland?

  29. Michael...I don't think so...all the talks I have seen suggest that global warming will be so strong it will overwhelming any effects on the thermohaline circulation you are talking about...cliff

  30. Michael...I don't think so...all the talks I have seen suggest that global warming will be so strong it will overwhelming any effects on the thermohaline circulation you are talking about...cliff

  31. Michael...I don't think so...all the talks I have seen suggest that global warming will be so strong it will overwhelming any effects on the thermohaline circulation you are talking about...cliff

  32. Cliff,

    Have you ever read "Not by Fire, But by Ice " by Robert W. Felix ?

    If so, what are your thoughts on it ? I'm no expert, so for all I know he's making the dates up, but everything seems to fit quite well into his theory.


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