Xtreme Weather: The Dangerous Delusion

In a paper published in the journal Climatic Change in March of 2012, Kevin Trenberth ambitiously sets out to redefine science. The paper’s title is a clue–“Framing the Way to Relate Climate Extremes”. The paper’s subject is not to publish the results of a new experiment or years of analysis of data. The paper is essentially PR advice on how to convince the public that weather is now influenced by the climate change we have experienced.

Gustavo Adrián Salvini

Gustavo Adrián Salvini

The question he attempts to answer is one asked of scientists frequently: “Is it (a particular weather event) caused by climate change?” He saves his answer for the final sentence in the paper: “In reality the wrong question is being asked: the question is poorly posed and has no satisfactory answer. The answer is that all weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be.”

This paper is essentially a follow-on from published work in 2011 where he attempted to invert the null hypothesis regarding global warming, something that I will take up in another post. For now let me just say that it is every bit as ambitious in its attempt to redefine the norms of science as this one.

Since Trenberth’s publication, many in the media, including this section of the blogosphere, have taken his dictum to heart. People had been blaming climate change for bad weather as far back as Hurricane Katrina, but it has taken off in the past year in a big way.

This is a dramatic change from what science presented to us prior to 2012. Dramatic storms, floods and droughts were offered to us as previews of coming attractions by scientists–things that might become more common as global warming continued later in this century.

Indeed, in a sign that not everybody agrees with Trenberth, two weeks after his publication the Intergovernmental Panel on Climate Change published a special report titled ‘Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation.’

The language in the report is clear:

“There is medium evidence and high agreement that long-term trends in normalized losses have not been attributed to natural or anthropogenic climate change,” writes the IPCC in its new Special Report on Extremes (SREX) published today.

“The statement about the absence of trends in impacts attributable to natural or anthropogenic climate change holds for tropical and extratropical storms and tornados,” the authors conclude, adding for good measure that “absence of an attributable climate change signal in losses also holds for flood losses”.

However, on this topic the IPCC, normally considered the authoritative source on such issues, was ignored in favor of Dr. Trenberth’s scarier conclusions.

It is hard to know how one could either prove or disprove Trenberth’s assertion. That, of course, is why it redefines science. But there are questions that I don’t think Dr. Trenberth has been asked, or at least hasn’t answered.

Is current weather extreme by historical standards? Are droughts drier, floods wetter, storms stronger or more frequent? If so, when did this start? (James Hansen has tried to answer this question with a paper published in PNAS titled ‘Perception of Climate Change,’ (and I will address it in another post), but I don’t think Trenberth has.

Let’s look at hurricanes, for example. The National Hurricane Center published an NOAA Technical Memorandum titled “The Deadliest, Costliest and Most Intense United States Tropical Cyclones from 1851 to 2010“.

  • Only one of the deadliest storms (Katrina) happened after 2000 and only one after 1950 (Audrey in 1957)
  • On the other hand, all of the costliest hurricanes are very recent. Sadly, this is because they did not adjust for inflation or people moving in greater numbers to affected areas. Pielke and Landsea 1998 found no trends in normalized lossesa finding subsequently replicated by Katz 2002 . Recent analyses of longitudinal geophysical data find that there are no trends on hurricane frequency and intensity at U.S. landfall. Landsea 2005, 2007; Emanuel 2005 . (Update: On rereading the article I note that they did try and normalize costs in a later table. They found 3 hurricanes in the top 10 costliest since 1945)
  • Only two of the strongest ten hurricanes since 1850 occurred during the period when global warming is considered to have accelerated (Katrina and Andrew)

So–what does history tell us about global warming and hurricanes? I don’t know and I’ll bet you don’t either. Because there is literally no evidence that could either prove or disprove Trenberth’s assertion, there is no way of knowing.

I will be taking this up in a series of posts similar to what I just finished doing with Matt Ridley’s essay for the GWPF. But the point I want to make now is that, if Trenberth is wrong–if he’s advising scientists to tell people that any bad storm, drought or flood is caused in part or in whole by global warming–then he is giving a terrible hostage to fortune.

If your strategy for communicating urgency about climate change depends on the weather then you are vulnerable to the oldest trick in the book–when the weather is nice people don’t think about it. And if the worst phenomena occurring today are in fact previews of coming attractions, we will need more than seasonal support to address it.

  1. When did Xtreme Weather begin?
  2. How do we distinguish between events influenced by climate change and events that are not?
  3. What is the degree of change we see in individual events?
  4. What is the level of confidence in your calculations?

11 responses to “Xtreme Weather: The Dangerous Delusion

  1. This is what I do. When someone attributes a random weather event to anthropogenic global warming theory, without any reference to trends in established data sets, I move that individual from my credible source list to my raving looney list.

    This doesn’t need to be complicated.

    To put this metaphorically, if you’ve ever had one of those crazy girlfriends that make you question your own rationality, then it’s probably time to stop hanging out with the girlfriend, rather than try to broaden your definition of what’s rational.

    • ” I move that individual from my credible source list to my raving looney list.” That’s what I’ve been doing here. If someone attributes extreme weather to AGW, I move them to my loony list. Same if they call Obama a Marxist, and so on. For the last four articles, 76% of the comments (excluding Tom) were from my loony list.
      I have many unpopular views. And I know the’re unpopular, so I keep them to myself. If these people don’t realize how they discredit themselves, they must be very self centered or lead very insular lives.

      • I’m a sceptic in both senses of the word. I have a long “raving looney” list too, and there are some sceptics on it . I also have many unpopular views, which I don’t keep to myself; some of those views will be unpopular with some sceptics, perhaps many. I’ll excoriate anyone (and have done) who exaggerates, distorts, lies by omission, or just plain lies. I respect anyone who does the same, whatever their views, even if those views are in direct opposition to mine. I respect anyone who’s come to a view through careful weighing of the evidence – all the evidence, and whatever their conclusion(s) might be. A lot more integrity and a lot less arm-waving and bluster might just clear some of the fog and make the picture clearer for those who’re confused by it all.

  2. When eugenics was the dangerous faux science delusion of the day, eugenics promoters would take some crime event or social problem and claim it was proof of the truth of eugenics. Trenberth is just acting out the same schill role for AGW extremists.

    • There are interesting parallels between CAGW and eugenics. The eugenics movement claimed credibility by reference to Darwin’s work. Think of this as the equivalent of CAGWers appeals to radiative physics. Eugenics also appealed to popular fears of the day – cheap mass international transportation had become possible. Immigration was rising.

      • The parallels are disturbing, frankly.
        Eugenics enabled the worst of the bigotry and prejudice of the day to become enshrined in law. When I drive by open spaces cluttered with windmills (many not working), I realize the AGW kooks are doing the same.

  3. One assumes people who are supposed to be experts in the area can read the same graphs I do. It’s not clear how they reach their conclusions. The recent Sandy linkage is a misnomer and the failure of most environmental reporters to be properly skeptical is a scandal in itself.

    Normalized US losses

    Normalized US Hurricane Intensity

    Global Tropical Cyclone Landfalls

    The US Intense Hurricane Drought

    Global Hurricane Frequency

    Global Accumulated Cyclone Energy

  4. One assumes people who are supposed to be experts in the area can read the same graphs I do. It’s not clear how they reach their conclusions. The recent Sandy linkage is a misnomer and the failure of most environmental reporters to be properly skeptical is a scandal in itself.

    • I think it’s crystal clear how they reach their conclusions – in the absence of any evidence. Extreme weather is what we used to get from time to time, and still do of course, but journalists have memories that don’t extend further back than their last paycheck, and access to archives they don’t use unless bashing a political opponent,

      • I think there is a correlation between youth and acceptance of weather = AGW. Older people have lived through a lot more weather extremes, and they are generally, well, wiser. Especially to the end is nigh stories from politically motivated interests.

      • I’m “older people”, and I’d like to think I’m “generally, well, wiser”, though there may be an element of ego in that assessment.

        I’ve certainly lived through some “weather extremes”. Why, I remember one Tuesday when absolutely nothing happened weather-wise!

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