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NOAA Scientist Says It’s ‘Misleading’ To Blame Global Warming For Hurricane Harvey’s Rainfall

February 6, 2018

By Paul Homewood


NOAA’s leading hurricane scientist, Chris Landsea, has recently published an analysis of Hurricane Harvey, and concludes that it is totally misleading to blame global warming for the record rainfall.

Michael Bastasch has the story at Climate Change Dispatch:


It’s “misleading” to blame Hurricane Harvey’s record rainfall, or hurricane rainfall in general, on man-made global warming, according to a National Oceanic and Atmospheric Administration (NOAA) scientist.

“Linking hurricane rainfall to global warming today (and even decades from now) based upon such a tiny contribution is misleading,” Christopher Landsea of the National Hurricane Center wrote in an analysis of the potential links between warming and Harvey.

“Moreover, such a fixation can delay steps that can be taken now to better mitigate the effects of extreme flooding from hurricanes,” wrote Landsea, a veteran hurricane expert.

Hurricane Harvey brought record levels of rainfall to southeastern Texas when it made landfall in late August. Much of Texas was covered in at least two feet of rain, with areas east of Texas seeing more than five feet. The storm is estimated to have caused $125 billion worth of damage and directly responsible for nearly 70 deaths.

Almost immediately, some scientists and activists linked the deluge to man-made global warming. At least three studies have come out blaming warming for Harvey’s record rainfall, but Landsea came to a different conclusion.

Landsea examined the data surrounding theoretical and climate model-based arguments linking man-made warming to hurricane rainfall. What he found was global warming played, at most, a “tiny” role in the storm.

“Scaling the results from both theories as well as climate model projections suggest, then, that roughly 3% of hurricane rainfall today can be reasonably attributed to manmade global warming,” Landsea wrote.

“This value is a rather tiny contribution,” Landsea wrote. “Thus only about 2” (50 mm) of Hurricane Harvey’s peak amount of 60” (1525 mm) can be linked to man-made global warming.”

But even then, Landsea noted that any “interpretation of Harvey’s rainfall is also made more uncertain because the source of much of the rainfall was due to the interaction of the very slow moving tropical storm with a stationary frontal boundary along the Texas/Louisiana coast.”

Harvey made landfall in Texas as a Category 4 hurricane, but most of the rainfall came while Harvey was just a tropical storm. But what made the rainfall particularly bad was Harvey stalled over Houston, therefore more rainfall was concentrated in a smaller area.

That’s a major problem for studies attempting to link Harvey’s rainfall to man-made global warming. Two Harvey studies did not actually look at the storm itself, rather relying on climate model simulations.

Another study from the Lawrence Berkeley National Laboratory admitted that “precipitation rates were not particularly unusual for a hurricane of this magnitude.”

Landsea did not address every study linking Harvey to global warming, instead focusing on just one of them written by Massachusetts Institute of Technology climate scientist Kerry Emanuel.

Emanuel concluded global warming led to “a sixfold increase” in the odds of Harvey-level rainfall pummeling Houston in any given year and an 18 percent chance of such rainfall by the end of the 21st Century.

“These projections appear, in my view, to be extremely inconsistent with current theoretical rainfall projections as well as explicit dynamical model forecasts from climate models as detailed above,” Landsea wrote.

“Bottom line is that there has not been a meaningful change in U.S. tropical storm and hurricane rain over the last century, but that there have been few studies to address the topic lately,” Landsea wrote about long-term trends in hurricane rainfall.


Landsea makes several pertinent remarks:

1) Theory suggests that the amount of rainfall in the tropical latitudes would go up about 4% per degree F sea surface temperature (7% per degree C).

The tropical North Atlantic Ocean, Caribbean Sea, and Gulf of Mexico have warmed up about 0.7  F (0.4 C) in the last few decades, much of which appears to be due to anthropogenic climate change (increased greenhouse gases)xix. Scaling the results from both theory as well as climate model projections suggest, then, that roughly 3% of hurricane rainfall today can be reasonably attributed to manmade global warming. This value is a rather tiny contribution. Thus only about 2” (50 mm) of Hurricane Harvey’s peak amount of 60” (1525 mm) can be linked to manmade global warming.

 This is a point I have made in the past about extreme UK rainfall. For instance, rainfall in England during the record winter of 2013/14 was 401mm. Even assuming that the theory is right, a warmer atmosphere would only account for maybe only 12mm of this, barely noticeable.


2) Landsea mentions Amelia, Claudette and Allison, in 1979, 1979 and 2001 respectively. He also mentions Hurricane Easy, which hit Florida in 1950.

All had similar intensity, or greater. What made Harvey’s rainfall much greater was the fact that the storm stalled.


3) He mentions a study from 2004, by Pavel Groisman, which could not identify any significant upward trend in rainfall from tropical storms in the Southeastern United States, between 1900 and 2000. The study did, however, find multidecadal variations.



What is particularly noticeabe is the big increase in the number of stations (red curve). When you are looking for “extreme events”, the more stations you use, the more events you will find.

As we have seen with Harvey, most of the rainfall fell over a very small area.


Landsea concludes by declaring Emmanuel’s findings as unreliable.

He finishes by asking what lessons can be learned:


What lessons can be learned from Harvey’s catastrophic flooding?
There are several important points that should be recognized in the aftermath of Harvey’s impact:
1. Hurricanes (and Tropical Storms) have been associated for millenniums with extreme rainfall and freshwater flooding. There is nothing that one can do to prevent these storms from occurring, hitting land, and impacting people;
2. Massive flooding and catastrophic impact from tropical storms and hurricanes occurs when the system moves slowly over a major city. This is precisely what happened because of Harvey as a tropical storm over Texas;
3. Flooding is made worse when extreme rainfall occurs over impervious land (such as roads and buildings) and the rain cannot soak in. Land use decisions should better consider allowing building (or rebuilding) in flood prone areas;
4. Studies should be made to see if evacuating people in advance of extreme flooding rain is feasible. (Currently, only evacuations from hurricanes are primarily issued from possible storm surge – salt-water – flooding. However, because the skill of in day-to-day rainfall amounts and locations continues to improve, it might be feasible to call for limited evacuations in the most vulnerable locations.);
5. Linking hurricane rainfall to global warming today (and even decades from now) based upon such a tiny contribution is misleading. Moreover, such a fixation can delay steps that can be taken now to better mitigate the effects of extreme flooding from hurricanes. See the following sites for more action today that can be taken: the Federal Emergency Management Agency (FEMA), the Insurance Institute for Business and Home Safety (IIBHS), the Environmental Protection Agency (EPA), and academia


 They are all commonsense conclusions. But the last one is particularly important.

How often do we hear global warming blamed for all sorts of bad weather? Pretending that we can solve the problem by building lots of wind mills and solar farms simply distracts attention from the practical things which really could make a difference.


Landsea’s paper is here.

  1. Don B permalink
    February 6, 2018 7:29 pm

    Illustrating that rainfall from stalled hurricanes is nothing new:

    “Cuba got hammered by more than 100 inches of rain when Hurricane Flora sat over the island for four days in 1963. And even earlier, in 1909 before hurricanes were named, a storm dropped more than 96 inches of rain on Jamaica. In more recent history, Wilma dumped more than 62 inches of rain on Mexico in 2005 and Hurricane Mitch, blamed for killing more than 11,000 in Central America in 1998, soaked Nicaragua with more than 62 inches, according to records compiled by National Oceanic and Atmospheric Administration forecaster David Roth.”

  2. Doug permalink
    February 6, 2018 7:47 pm

    No doubt he will be bullied and hounded out of his job. All for telling the truth to the Greens/Climate Nazis

    • dave permalink
      February 6, 2018 9:56 pm

      “…hounded out of his job…”

      Unless he knows something we don’t know, namely, that the pendulum is swinging back.

      • markl permalink
        February 7, 2018 1:38 am

        “..pendulum is swinging back…” Yes, and Trump helped push it. It’s good to see some common sense being displayed. More countries are looking for ways out of the Climate Change holes they’ve dug for themselves.

      • dave permalink
        February 7, 2018 8:23 am

        According to Rasmussen Polling,Trump’s approval rating among “likely US voters” is 49% favourable .

        Another reason, perhaps, for a certain resurgence of boldness among professional meteorologists, is that they can always get jobs outside of Government advising businessmen.

        In the write up by Landsea I was disappointed but not at all surprised to see yet another scientist who has entirely forgotten his high school instruction when trying give a “folksy” explanation. Warmer air does NOT “hold” more water vapour in any sense. The vapour pressure above liquid water is entirely determined by the temperature of the surface water.

        The only time that you might need to think about the result of the air getting a little warmer is if the dew point is already almost as high as the ambient temperature. (Since the dew point can never be higher than this.)

        The next time one is poaching an egg one should observe carefully what is happening to the boiling water. Just above the surface one does not observe anything. That is the zone of water vapour – real steam. Then you see some apparent steam – which is really vapour condensing into liquid water. Then you see nothing further up. That where the water changed BACK to vapour as it was diluted by air. Making your kitchen warmer will not change any of this. Turning off the heat under the water will.

  3. Broadlands permalink
    February 6, 2018 8:14 pm

    It is equally misleading to blame the recent record cold on both sides of the Atlantic to “global warming”…as was done by some.

  4. Roy W. Spencer permalink
    February 6, 2018 10:14 pm

    I’m glad to see Landsea weighing in on this. I suspected that the rain rates in Harvey were no unusual. It was the combination of stalling and proximity to the Gulf.

  5. Athelstan permalink
    February 6, 2018 11:03 pm

    Well done NOAA!

    er if I may just add, one tiny criticism, why didn’t they call out the alarmunists a bit earlier, say, in the aftermath of named ‘Storm Harvey’ because some people did – they guy who runs this blog for one – Paul Homewood.

    • Hivemind permalink
      February 7, 2018 12:48 am

      In his defence, it takes time to write academic papers, at least with any quality. And it is through academic papers that this sort of people seek to improve our knowledge and influence policy makers.

      • Athelstan permalink
        February 7, 2018 8:55 am

        I do concede your point about academic papers.

        However, NOAA and the alamists were doing a very good job of facetious association, attributing the ‘Storm Harvey’ event on some arrant supposition. Even if the likes of NOAA did not specifically aver it, the guilt by association was always clear in the subtext that: man made warming was somehow and by some stretch the culprit. A slick world campaign, as if by magic and everybody got to know it – in the UK the beeb was bellowing “global warming!” at the tops of their voices and I’m quite sure that across the EU the same lies were beamed to their respective audiences, from Rai, to ARD, to TF1.

        Get the lies out first and then quietly whisper months later – “it wasn’t me mister” – but outside of the fetid, symbiosis and hermetically sealed at that circles of academia and blogs such as this no one but no one will ever hear the apology – ain’t it the convenient way – eh?

        Though, as the harsh glare sweeps, the cold light of reality seeps into to these governmental agencies, maybe we’ll see a bit more truth oozing out and jumping on the global warming bandwagon – the spring in their step maybe just got very much more leaden.

        Politics = advocacy = funding, you get what you pay for and always: follow the money.

  6. Bitter@twisted permalink
    February 7, 2018 8:13 am

    I’m sure the BBC will breathlessly report this.

    • dave permalink
      February 7, 2018 8:31 am

      “…the BBC…”

      Will assume he is a billionaire hillbilly appointed by Trump.

    • Gerry, England permalink
      February 7, 2018 1:43 pm

      Talking of breathe, I wouldn’t hold yours.

  7. dennisambler permalink
    February 7, 2018 10:11 am

    “Thus only about 2” (50 mm) of Hurricane Harvey’s peak amount of 60” (1525 mm) can be linked to man-made global warming.”

    Can any rain fall really be linked to “man-made global warming”? Using their language gives them undue credibility.

    Kerry Emmanuel went to the dark side years ago when he became involved with selling climate insurance:

    “In the Eye of the $torm – Kerry Emmanuel – The Non Political Scientist”

    • Mike Jackson permalink
      February 7, 2018 10:43 am


      Eliminate that phrase “man-made” and there might be some justification.

      Meanwhile, do I detect a small falling-out in the climate community here? That can only be good for real science!

      • Athelstan permalink
        February 7, 2018 11:19 am

        “Meanwhile, do I detect a small falling-out in the climate community here? That can only be good for real science!”

        Mr Jackson, I really do hope that, your perceptive senses are correct – they usually are.

    • dave permalink
      February 7, 2018 11:44 am

      “…can any rain fall really be linked to…?”

      Of course not.

      Similar nebulous questions of mixed causality arose in the study of econometrics, fifty years ago, and the best that could be done was to invent statistical approximations of the idea, such as “Granger causality” in linked time series. However, this is simply another area where “climate scientists” fail to grasp quite elementary ideas.

  8. February 7, 2018 5:06 pm

    ‘such a fixation’


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