New study asks: More tropical cyclones in a cooler climate?

With historical peak of the Atlantic hurricane season just weeks away, NOAA’s Climate Prediction Center is preparing its updated outlook for the remainder of the season to be released today at 11 AM.To-date, three named storms have formed in the Atlantic basin: Ana, Bill, and Claudette. The Atlantic hurricane season began June 1 and continues through November 30. Previously, NOAA’s Climate Prediction Center said the 2015 Atlantic hurricane season will likely be below-normal. Given this new study, I wonder how future outlooks might play out if they give up on the idea that a warmer world equals more hurricanes?

Key Points of this new study:

  • 4K cooler climate experiment is conducted using a high resolution AGCM
  • Number of TCs is significantly increased in the 4K cooler climate
  • Tropical cyclone genesis can occur at SST well below 26˚C

Masato Sugi, Kohei Yoshida,  Hiroyuki Murakami

Accepted manuscript online: 31 July 2015 DOI: 10.1002/2015GL064929

More tropical cyclones in a cooler climate?

Abstract

Recent review papers reported that many high-resolution global climate models consistently projected a reduction of global tropical cyclone (TC) frequency in a future warmer climate, although the mechanism of the reduction is not yet fully understood. Here we present a result of 4K-cooler climate experiment. The global TC frequency significantly increases in the 4K-cooler climate compared to the present climate. This is consistent with a significant decrease in TC frequency in the 4K-warmer climate. For the mechanism of TC frequency reduction in a warmer climate, upward mass flux hypothesis and saturation deficit hypothesis have been proposed. The result of the 4K-cooler climate experiment is consistent with these two hypotheses. One very interesting point is that the experiment has clearly shown that TC genesis is possible at sea surface temperature (SST) well below 26°C which has been considered as the lowest SST limit for TC genesis.

http://onlinelibrary.wiley.com/doi/10.1002/2015GL064929/full

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49 thoughts on “New study asks: More tropical cyclones in a cooler climate?

  1. I call this the computer game effect..
    Same thing you get when you cool the past, to increase the trend…extend the trend…and then wonder why you grossly overshoot the mark
    They are naming more storms, calling more storms that would have gone unnoticed….
    …then extending that trend … and of course, shows more storms

  2. From abstract-
    “One very interesting point is that the experiment has clearly shown that TC genesis is possible at sea surface temperature (SST) well below 26°C which has been considered as the lowest SST limit for TC genesis.”

    First, these are model runs, not experiments. It seems that modelers are fond of calling model runs ‘experiments.’

    Since the models predict an SST for TC genesis that is well below the (presumably) observed (as in the real world) value of 26 C, should one not conclude that the models are in fact incorrect?

    If the models already predict that warming SST leads to fewer TC’s (which of course disagrees with TC settled science from 2005 :-), isn’t this study unnecessary? Or is there an assumption that current SST’s are at some ‘goldilocks’ temperature?

    • Let’s of course not talk about the elephant in the climate room by not mentioning the fact that atmospheric CO2 levels are supposed to remain elevated for centuries. So in the climate change paradigm with the alarmist control knob stuck on hotter, maybe they just “tuned” CO2 out of the computer model? Sort of makes obvious like they tune the computer models to get whatever CO2 versus temp anomaly they want.

      • It should not go unsaid here that the half-life of atmospheric CO2 is only about 5 years, as with methane. It’s quite dynamic.

        And no gas at any concentration in the atmosphere can detectably warm the climate. So-called “greenhouse gases” are more accurately called “radiative gases.” Thus, water vapor and CO2 cool the air rapidly after sunset.

      • HIgley7 wrote: “It should not go unsaid here that the half-life of atmospheric CO2 is only about 5 years, as with methane.”

        Methane goes away because it is destroyed (oxidized). Carbon dioxide dissolves into the ocean and is converted to organic material by photosynthesis – a process that is easily reversed when organic materials are eaten or decay (eaten by microbes). So the half-life of CO2 in the atmosphere is unimportant.

        The easiest way to understand the turnover of CO2 is to look at what is happening today: We burn enough fossil fuel every year to raise CO2 levels by 4 ppm, but CO2 is accumulating at a rate of only 2 ppm per year. Therefore, 2 ppm worth of CO2 is dissolving in the ocean or converted to organic material by photosynthesis. If we stopped burning fossil fuels entirely, CO2 would start falling at a rate of 2 ppm per year. If we reduced CO2 emissions by 50%, CO2 levels would remain stable “indefinitely” – as long as the ocean and photosynthesis continued to take up CO2 at today’s rate. (The IPCC says stabilization requires an 80% reduction in emissions by developed countries, mostly because they know that other countries will increase their future emissions and partly because they estimate that the current uptake will slow or “saturate”.)

        So how can CO2 have a half life in the atmosphere of only 5 years, but take decades to return to normal? SImple. Every year decaying organic material and the oceans emit about 80 ppm worth of CO2, man emits about 4 ppm worth of CO2 by burning fossil fuels, and the oceans plus photosynthesis take up about 82 ppm worth of CO2. (Why does the IPCC say CO2 will stay high for centuries? They think uptake by uptake by photosynthesis will be saturated by the end of the 21st century and CO2 will only be taken up by dissolving into the deeper ocean. It takes about a millennium for the water to circulate through the deep ocean via the MOC.)

        Higley7 wrote: “And no gas at any concentration in the atmosphere can detectably warm the climate. So-called “greenhouse gases” are more accurately called “radiative gases.” Thus, water vapor and CO2 cool the air rapidly after sunset.”

        Your phrase “warm the climate” is meaningless. Things warm when they take up more energy from ALL sources than they release, so it is always incorrect to point to one source of energy and imply that it alone causes warming or cooling. Radiatively active gases have only three ways to take up and release energy: 1) collisions with other gas molecules (the major pathway in the troposphere), 2) absorbing a photon (usually followed by collisional relaxation of the excited state), and 3) emitting a photon (usually after collisional excitation). The rate of emission depends only on the local temperature, because collisions relax molecules excited by absorption much faster than they can emit. Laboratory experiments tell us precisely how much thermal infrared GHGs absorb and emit at various temperatures and pressures.

        The temperature of the atmosphere and its GHGs fall with altitude. (This lapse rate exists whether or not you mistakenly believe in a thermo-gravitational effect.) Averaging over day and night and the whole planet, the surface emits about 390 W/m2 of upward thermal infrared radiation, while only 240 W/m2 of thermal infrared radiation escape through the top of the atmosphere. This reduction in outward radiation is a consequence of the absorption and emission of GHGs in the atmosphere AND the decrease in temperature with altitude (lapse rate) in the atmosphere. This GHG-mediated reduction in outward flux permits the surface of the earth to average about 33 degC warmer than it would be otherwise and Venus to be 400+ degC warmer.

      • “This lapse rate exists whether or not you mistakenly believe in a thermo-gravitational effect.”

        Hahahahaha

        The lapse rate IS the gravito-thermal “GHE”:

        dT/dh=-g/Cp

        and has absolutely ZERO dependence upon “radiative forcing” from GHGs. In fact, dT is INVERSELY related to Cp, and GHGs INCREASE Cp, and thus DECREASE temperature.

  3. if global temps fall 4 K, humanity will have a lot bigger problems than a few more TC’s.
    As most at WUWT have recognized, colder is far worse for food production and energy needs than a similar magnitude of warming.

  4. Well, this is very interesting. I read some time ago that global temperature changes are most apparent at the poles, not so much at the equator. Thus for a cooling world the polar/equatorial temperature difference increases resulting in stronger winds and increased weather events. For a warming world weather events are less severe. What I have read above seems to support that scenario.

    • Richard, you are closing in on a truth here. Tropical storms are driven by differences in temperature – think of them like a heat engine. The greater the difference, the more powerful storms can be (or you can have a bunch of smaller ones to dissipate the same total energy). If the equator is held at constant temperature, and the poles warm, there is less temperature differential to drive the weather heat engine, so fewer or weaker storms should be expected. If we start a cooling period where the equator is held constant and the poles get colder, then expect stronger, more plentiful storms. There is no real floor to temperatures that can drive a storm – its the temperature difference that drives some really big storms on some colder gas giants elsewhere in the solar system (sure its all various gases, but the heat engine still works).

    • Richard,
      You’re absolutely right. In fact, as pointed out by Lindzen and others, a warmer world is indeed less stormy.
      Ironically, a standard piece of alarmism supports this: when the world warms, more warming occurs towards the poles (as more ice melts surfaces on average become darker and so absorb more heat). I believe the data also shows that less warming has occurred near the equator. Therefore the temperature difference between the equator and poles gets smaller.

      History confirms this. Go back a few centuries, when the climate was dominated by the Little Ice Age, and storms then were far worse. H.H.Lamb listed storms from the LIA that killed up to 100,000.
      In contrast, in recent decades the overall intensity of hurricanes has been falling. Compared to the LIA, when people were accused of “weather cooking” and condemned to death because the weather was so extreme, in the past century, and still today, we live in remarkably benign conditions.

      And yet, despite the actual science and data, according to the doom-mongers we’re even more doomed than ever!
      Chris

  5. Klotzbach & Gray’s August forecast is out, see http://hurricane.atmos.colostate.edu/forecasts/2015/aug2015/aug2015.pdf . They’re far more informative than the NOAA forecasts.

    Nothing surprising:

    FORECAST OF ATLANTIC SEASONAL HURRICANE ACTIVITY AND
    LANDFALL STRIKE PROBABILITY FOR 2015

    We continue to foresee a well below average 2015 Atlantic hurricane season. A strong El Niño event is already underway. Conditions in the tropical Atlantic remain unfavorable for hurricane formation. We continue to call for a below average probability of United States and Caribbean major hurricane landfall.

    They’ve lowered the Net Tropical Cyclone Activity (NTC, normal is 103) from 45 down to 40.

    (as of 4 August 2015)

  6. As a sailplane pilot, I love the Spring and Fall days when the air is cool and the ground is warm. The thermals are generally stronger and easier to find.

    I would think the same applies to any heat driven weather feature. If the air is cooler above a warm water (vs warmer air over the same water), common sense (and hot air balloons) would say cumulus and cumulonimbus clouds are more likely to form.

    In fact, I just wrote a program on my Mac and it says so, so it must be so.

  7. The climate is in a state of CO2-fueled confusion right now. It’s as if we humans as CO2-pushers have injected our climate with a powerful drug. It is desperately trying to sequester the millions and millions of Hiroshimas worth of heat into the deep oceans, and so far has been somewhat successful. There is a limit, though. The storms of our grandchildren are gonna be monsterous if we don’t change our ways. They will make Sandy look like a mere zephyr.
    Now, where did I put my Kool Aid?

    • “They will make Sandy look like a mere zephyr”

      Sandy was mainly caused by a -NAO, deep upper level low/trough(in the northeast US and southeast Canada from what is actually a cold weather pattern at mid-latitudes that captured a minimal, cat. 1 hurricane.

      The remnants of weak hurricane Sandy moved extremely slow/stalled.

      On the hurricane strength scale and with regards to tropical characteristics when Sandy was over the ocean, this was a weak system.

      You want an example of numerous hurricanes and one similar to Sandy but stronger as a hurricane in the same region?

      Go back to this same area in 1954, during global cooling:

      https://en.wikipedia.org/wiki/1954_Atlantic_hurricane_season

  8. I don’t have time to read the paper this morning, but 26°C lower bound has always been a bit squishy. Its strength is that the partial pressure of water vapor climbs quickly with temperature, so to support storms in cooler conditions requires very favorable other conditions, like cold temperatures aloft.

    Very strong nor’easters often develop an “eye-like” structure that sure looks like a tropical storm eye. They never last long, I suspect there is a transistion to a warm-core storm going on but there isn’t enough energy to maintain the eyewall long enough to send something out for a better look.

  9. Here’s a good example of an extratropical storm on March 26th last year (note the front hanging down from it) with an “eye-like” core:

    Near the core the front has been wrapped around so much I doubt there’s much frontal structure left.

    • exactly….I don’t know what they are trying to say here….do they think they just discovered extratropical TC’s?

    • @ Ric, I am confused by your description. You said the “front” is hanging down from it. I know I may sound like an idiot here but in weather terms where is the front located in a hurricane (TC) or even a depression, I was under the impression that the “front of any storm was the leading edge defined by the direction of the whole system. If moving in an NW direction then on the compass it’s “front” would be coming from the SE . Am I wrong here? On your picture I would have thought the front was along the coast of the Eastern Seaboard and Canada ( and slightly inland).

      • Here are some differences between tropical and extratropical storms (I really should say cyclone):

        tropical: powered by heat (and latent heat in water vapor) between the sea level and upper troposphere.
        extratropical: powered by horizontal temperature difference between cold air toward the poles and warm air toward the tropics.

        tropical: rotating air can’t reach the center of the storm and is forced upward, dry air falls down in the core, resulting in the eye structure.
        extratropical: air reaches the center of the storm, then warm air overrides the cold air maintaining the frontal structure of the system.

        tropical: relatively compact system thanks to the energetic processes always being pulled toward the core
        extratropical: energy is spread out along attached fronts, overriding air, etc.

        So yes – the arc of clouds in the photo is a cold front showing the cold air sweeping across the eastern US. A tropical storm would not have a front. (Tropical storms often get swept up into a cold front and that hastens their transition to extratropical.)

        A weather front, much like a pre-air war battle, is the dividing line between two air masses on the ground. A tropical storm doesn’t really have one – the core is essentially sucking up all the low level air and exhausting it out the top. The strings of thunderstorms that spiral into the center are feeder bands. I assume they take shape from local convective processes and help make space for more water vapor.

  10. I have mentioned this here for some time. Previous GCM studies have shown that when they warm their models they get *fewer* tropical cyclones. The IPCC AR5 acknowledged this, but in a sotto voce way so as not to draw attention to this.
    But in addition to studies using (unreliable) climate models, O’Brien et al (FSU) conducted a couple of studies of tropical cyclone activity during the Little Ice Age. Although the statistic are sparse, they indicate there was *more* TC activity during a cooler climate period.
    What I find amusing in all of this, here is a *benefit* from a warmer world, fewer hurricanes. Shouldn’t science organizations and news media be shouting the good news from the mountain tops? Instead, they ignore or downplay these studies. Let’s see how this latest paper plays out. I doubt anyone will be mentioning the warmer world=fewer hurricanes corollary.

  11. As an avid paraglider, tempature gradient is very important. The more gradient between day and night, the larger the thermals, the more dynamic the day will be. Perhaps in a warmer world there is less gradient and that is a contributing factor to fewer cyclones.

  12. More rewriting of history.

    Global warming consistently predicted there would be an increased number of and more intense hurricanes.

    This started to change when Ryan Maue started producing the data showing there was a general reduction. Ryan was attacked for a long time until they couldn’t ignore the data any longer.

    Now, its fewer hurricanes? Its even in the models?

    • But the BBC, and MSM have not got that message.

      They keep pushing the meme that with GW we will get more storms/hurricanes/cyclones and those storms/hurricanes/cyclones will be more intense because there is more heat powering them and more water vapour locked up in them.

    • Bill-that the number of Tropical Cyclones would probably decrease in a warmer world is a prediction dating back to at least the 1990s, for example:

      Bengtsson, L, et al., (1996). Will greenhouse gas-induced warming over the next 50 years lead to a higher frequency and greater intensity of hurricanes? Tellus, 48A, 57-73.

      Don’t confuse what activists who don’t study Tropical Cyclones say with what actual experts of Tropical Cyclones believe. And don’t confuse what alarmist say models say, with actual model results.

      It’s certainly true that increased intensity has been a consistent prediction. It’s also been fairly consistently predicted that any increase in intensity would be too small to be detectable at this time, or indeed for many more decades yet.

      Also climate models can’t really resolve Tropical Cyclones, you need to use a climate model to generate general weather conditions and then put those synthetic conditions into an operational weather forecasting model, to make predictions about what happens with Tropical Cyclones. This is why many climate modelers make false statements about Tropical Cyclones and climate change. In addition to the fact that many of them are quite simply saying whatever they think will scare people, rather than what the science-yes, their own scientific theories and models-actually predict.

      • One study said less hurricanes and then the author was attacked from all sides including up until the last two years when the warmers forced him off the board of GWPF.

        Several articles on this at WUWT for example.

        https://wattsupwiththat.com/2014/05/15/uk-times-headline-tomorrow-scientists-in-cover-up-of-damaging-climate-view-full-article/

        [For the other readers, please clarify what the GWPF organization is, and what country it is affiliated with/funded by. .mod]

      • Bill, this is a perfect illustration of what I’m talking about. Bengtsson was allowed for years to publish papers predicting declines in the number of Tropical Cyclones. What he eventually got attacked for, was having the temerity to threaten the public message, not to go against the mainstream scientific view of the subject, which he has always represented.

        And it wasn’t just the one study. Numerous modeling studies came to the same conclusion. For example:

        Yoshimura, J., M. Sugi, and A. Noda, 2006. Influence of greenhouse warming on tropical cyclone frequency, Journal of the Meteorological Society of Japan, 84, 405-428.

  13. Not being able to read the paper, I wonder if all conditions that are necessary for the development of TCs were taken into consideration. Temperature is not the only factor in storm development. Shearing winds, dry air, high pressure aloft all have positive or negative effects. But off the cuff, I would have to agree that since it is rare to see a real warm core TC develop over waters under 26C, the results are wrong.

    • Tom-Generally the reason models predict a lower number of tropical cyclones at higher temperatures is because warmer climates, at least in models, have enhanced wind shear. The result they got wouldn’t be possible if they only considered the effects of temperature directly.

  14. So colder = more TCs and warmer = fewer TCs. Disproves CAGW alarmism over TCs, insurance claims, etc. Oh no! What can we do?!

    Let’s throw in a diversion about TCs forming over colder seas than we thought. Therefore just because we’re not seeing any warming it doesn’t mean that we can expect fewer TCs. And we don’t need to tell the public — they’ll continue to think TCs are caused by AGW because that’s what we told them before. Job done.

    • The IPCC reports do in fact say that there has been no increase in storms, tornados etc. and that insurance losses are not due to extreme weather:

      “There is medium evidence and high agreement that long-term trends in normalized losses have not been attributed to natural or anthropogenic climate change”

      “The statement about the absence of trends in impacts attributable to natural or anthropogenic climate change holds for tropical and extratropical storms and tornados”

      “Current datasets indicate no significant observed trends in global tropical cyclone frequency over the past century…”

      https://wattsupwiththat.com/2013/10/03/pielke-jr-agrees-extreme-weather-to-climate-connection-is-a-dead-issue/

      However, you are right. In spite of this scientific evidence the doomsayers and the media continue to say that extreme weather is increasing and claim this is due to man-made climate change and that that is the scientific consensus, when it is in fact the opposite.

    • Ren, you must have a high threshold in mind for what constitutes a “strong” cyclone. Hurricane Wilma was comparable in terms of central pressure to Typhoon Nancy, respectively the 1st and 8th most intense cyclones in their respective basins that have been observed, when ranked by lowest pressure. And Wilma had a peak 1-min wind speed of 185 mph, just 5 mph slower than Typhoon Tip, which remains the record holder for strongest tropical cyclone ever recorded.

      Western Pacific cyclones tend to be stronger (and their central pressures are significantly lower, even at comparable maximum wind speeds) but by any reasonable measure, the Atlantic is perfectly capable of generating strong cyclones.

  15. You mean to tell me now that Al Gore and all his followers with PHD degrees from former premier institutions of learning and research actually lied when they told us there will be more hurricanes on the East Cost due to global warming. It seems that actual count also confirms that they were lying in order to get more lucrative grants from government.
    Where are the consequences? More grants from the Administration?

  16. In these studies, what was the cause of hypothetical temperature change of 4K? That affects the temperature of the tropical tropopause. An increase of solar radiation will warm all levels of the atmosphere. But an increase of greenhouse gases cools the tropopause, which favors more convection.

  17. A day or two ago we had a chap from Environment Canada on CBC radio tell us that only three named storms had formed so far this year, but the impression that I took away from his presentation was that there was still hope that the rest of the year would be more productive and that we could still have some big ones with destructive landfalls.
    cynicism/off

  18. By looking at the severe cyclone storms occurrence data in Bay of Bengal and Arabian Sea during 1891 to 1990, they were/are concentrated in both summer/pre-monsoon [Aprl & May months] and winter/post-monsoon [October to December] with more frequent in later low temperature period after southwest monsoon. Also, the frequency of occurrence follow a 56 year cycle similar to northeast monsoon. During the monsoon season [June to September] depressions/cyclonic storms are common.

    Dr. S. Jeevananda Reddy

  19. Tropical storms work on heat. The theory gives that the warmer the planet the more storms.

    BUT:- The storms may not work just on heat but temperature difference. The tropics will not warm/cool at the same rate as the poles so a warmer planet has a lower temp. difference to that of a cold planet so cold planets get stronger storms warm planets weak storms. This is born out by looking at the LIA when recorded storms were more numerous than today.

    • John-cyclonic systems do indeed run off of temperature gradients. For extratropical cyclonic storms, the reduced equator to pole temperature difference should reduce their frequency and intensity. But for tropical cyclones, horizontal temperature gradients are mostly irrelevant, since temperature doesn’t drop off as quickly with higher latitude in the tropics as it does at higher latitudes. Instead, the important temperature gradient for tropical cyclones is the vertical temperature gradient. The behavior of the vertical lapse rate is much more ambiguous, so knowing what will happen with tropical cyclones is not obvious a priori. Additionally, other factors in the tropical environment can be much more important. Modeling studies generally point to fewer in number, as this one does, in a warmer environment, and perhaps a small increase in the intensity of the ones that still form, but not large enough to be measured yet.

      As far as evidence goes, so far the frequency prediction looks like it’s probably correct. But on intensity the observed data gives us little reason to be anything other than agnostic.

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