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Comments 51 to 75 out of 93:

51. Composer99 at 03:45 AM on 27 July, 2012
    David: In addition to the comments by Dikran and DSL, I should like to note that the additional energy in the system resulting from greenhouse warming is not evenly distributed, temporally or spatially. As such the potential exists for larger gradients leading to more intense storm activity, as suggested by the Intermediate version of this article and comment #47 (although as per that comment and the IPCC SREX more research is needed to confirm whether this is occuring).
52. David Friedman at 13:44 PM on 27 July, 2012
    To Dikran: Look up "perpetual motion machine of the second kind." As I already said, it doesn't violate conservation of energy, it violates the second law--that entropy tends to increase, not decrease. For what it's worth, I have a doctorate in physics. To DSL: As you can see if you read what I wrote, I'm not claiming that the conclusion of the argument is wrong--I don't know if it is. I'm claiming that the argument is wrong. The argument didn't say that global warming would occur more in hotter air than in cooler air, which is what your argument would require--whether it's true I don't know. It said that because there was more thermal energy available, storms would be either more frequent or stronger. That's bad physics, for the reason I explained.
53. Daniel Bailey at 13:48 PM on 27 July, 2012

    "For what it's worth, I have a doctorate in physics."

    That's a crap argument. And I've heard many.

    "it doesn't violate conservation of energy, it violates the second law"

    If you are going to argue the 2nd Law meme, take it to the appropriate thread.
54. Tom Curtis at 14:49 PM on 27 July, 2012
    David Friedman @48, a hurricane is formed by updrafts forming over warm waters. The updraft carries warm water vapour to high altitudes, cooling it in the process. This progressively condenses the water vapour, releasing latent heat. The release of latent heat slows the cooling of the air in the updraft which is cooling due to adiabatic expansion as it rises. This allows the air to rise faster, increasing the rate at which fresh water vapour is drawn into the system and hence strengthening the storm. Should a hurricane pass over land, the lack of water vapour being drawn into the updraft results in a rapid weakening of the storm. With increased heat, there is more water vapour in the atmosphere. This preferentially strengthens storms because in stable air or downdrafts, there is little condensation of water,and hence little release of latent heat. Given this, the brief description in the basic rebuttal is true, if simplistic. It does not constitute a fallacious argument, as you maintain, because it is not an argument. The reason it is not an argument is because there are other significant factors, and it is unclear what the actual effect of this additional available energy in the form of increased water vapour will have. It merely points out that increased energy may have one of (at least) two potential effects without detailing the mechanisms involved.
55. scaddenp at 15:17 PM on 27 July, 2012
    Daniel, I dont think David is arguing that "AGW violates the 2nd Law" which is loony tunes stuff. I believe is arguing the mechanism proposed in the article for hurricane formation violates 2nd Law. However, it isnt clear to me why David thinks the argument of "more thermal energy in the atmosphere can create bigger storms" violates second law. The article notes empirical evidence but for discussion of the physical evidence then that cites for: Emanuel, K. (2005), Increasing destructiveness of tropical cyclones over the past 30 years, Nature, online publication; published online 31 July 2005 | doi: 10.1038/nature03906 Knutson, T. K., and R. E. Tuleya, 2004: Impact of CO2-induced warming on simulated hurricane intensity and precipitation: Sensitivity to the choice of climate model and convective parameterization. Journal of Climate, 17(18), 3477-3495. in scholar might be worth looking at.
56. IanC at 16:49 PM on 27 July, 2012
    I agree with David that the statement is factually incorrect. A hurricane is a Carnot heat engine, and its efficiency e is dictated by the ratio of the temperature between the heat source (T_H) and heat sink (T_C) i.e. e = 1- T_C/T_H The Carnot engine is the most efficient engine you can have within the limits of the second law. If both T_C and T_H increase with T_C increasing more, you will end up in a situation where more thermal energy actually results in less energy available to the storm itself. The conclusion "more energy to drive storm" therefore violates the second law. Fortunately of course the Tropopause is cooling and the surface is warming, so T_C/T_H is decreasing and the efficiency is going up, and therefore the conclusion holds. The reasoning should however be adjusted I think.
57. Dikran Marsupial at 20:53 PM on 27 July, 2012
    David Friedman Looking up perpetual motion machine of the second kind gives "2. Also called perpetual motion of the second kind motion of a hypothetical mechanism that derives its energy from a source at a lower temperature. It is impossible in practice because of the second law of thermodynamics. I'm pretty sure that the energy source (the sun) is at a higher temperature than the Earth. ;o) According to Wikipedia, "A perpetual motion machine of the second kind is a machine which spontaneously converts thermal energy into mechanical work. ..." Well I have a Crookes' radiometer in my workshop, which does just that, so there must be more to it than that. When the thermal energy is equivalent to the work done, this does not violate the law of conservation of energy. However it does violate the more subtle second law of thermodynamics (see also entropy). The signature of a perpetual motion machine of the second kind is that there is only one heat reservoir involved, which is being spontaneously cooled without involving a transfer of heat to a cooler reservoir. This conversion of heat into useful work, without any side effect, is impossible, according to the second law of thermodynamics. As Tom points out, storms are formed by updrafts over warm water that take warm moist air up higer into the atmosphere, which is cooler. Thus there is no contravention of the second law of thermodynamics, as far as I can see. Your PhD in physics means very littlle. I have a PhD as well, and I am an active researcher in my own field (essentially statistics), and have a h-index over 20. Does that mean that my arguments on statistics have any greater strength than if they came from somebody else? No not really. There is also the point that the authors of the papers on which this article is based also have PhDs, and more importantlty are also experts on this particular topic. You would be better off explaining your scientific objection in more detail in a more moderate manner, the postuting does you no favours at all, it just isn't the way science should be done.
58. Daniel Bailey at 21:29 PM on 27 July, 2012
    Phil, since David is either being purposefully obtuse or simply unclear, I clarified my assessment with "if". Hence, if the root argument he makes is based on a misunderstanding of the greenhouse effect, the comments could then stay here or go to one of the more applicable GHE threads. If it is based on a misunderstanding of the applicability of the 2nd Law, then it should go as directed. Either way, my comment holds.
59. IanC at 03:04 AM on 28 July, 2012
    Dikran, Kelvin's version of the second law states that No process is possible in which the sole result is the absorption of heat from a reservoir and its complete conversion into work. i.e. some of the heat extracted from the warm source must be transferred into the cooler reservoir. Effectively the 2nd law states that not only do you need a cold reservoir to receive the heat that is not converted to work, there is also an upper limit to how much work you can extract. Any statement indicating otherwise amounts to a violation of the second law, and any machine that is more efficient then what 2nd law allows is a perpetual machine. Having a cooler reservoir is necessary but not sufficient to comply with the second law. You also have to make sure that the machine does not do more work than the second law allows.
60. Dikran Marsupial at 03:37 AM on 28 July, 2012
    cheers Ian, you do a much better job of explaining the issue! It seems to me one of those things where a straightforward presentation for the general public isn't actually the whole truth, but is enough to convey the basic idea. Perhaps there needs to be an advanced version of the post?
61. DSL at 03:43 AM on 28 July, 2012
    I still don't see where the comment in question: "The background to these enquiries stems from a simple observation: extra heat in the air or the oceans is a form of energy, and storms are driven by such energy. What we do not know is whether we might see more storms as a result of extra energy or, as other researchers believe, the storms may grow more intense, but the number might actually diminish." is claiming that "all energy" is being converted to mechanical. 1. The background to these enquiries stems from a simple observation. 2. extra heat in the air or the oceans is a form of energy 3. and storms are driven by such energy. 4. What we do not know is whether we might see more storms as a result of extra energy 5. or, as other researchers believe, the storms may grow more intense, but the number might actually diminish. Is it in point 3, the "such" of which I read as "increased lower trop and sea surface temp"?
62. IanC at 05:09 AM on 28 July, 2012
    Dikran, Yes it is really a subtle point, and I probably won't have picked it up either if David hadn't point out the problem. However no matter how simple the argument is, I agree that the argument should be as accurate as possible. Given that the strength of a hurricane theoretically depends on temperature contrast between the surface and tropopause, rather than the temperature itself, we should make that clear. I suggest that instead of "extra heat in the air or the oceans is a form of energy, and storms are driven by such energy", we can replace it with "due to the greenhouse effect, the surface is warming relative to the top of the atmosphere, which in turn increases the amount of energy available for driving hurricanes." I believe it is consistent with the physics, yet avoids the need to discuss the thermodynamics. An advance version, where the thermodynamics can be examined in greater detail, will certainly be useful. When I attended a talk given by Kerry Emanuel a few months ago I was quite fascinated by the theory, and found thermodynamics to be interesting for once!
63. David Friedman at 02:51 AM on 4 September, 2012
    To IanC--thank you for understanding the argument. While I'm correcting the page, there is a related but still more subtle error on it: "Recent research has shown that we are experiencing more storms with higher wind speeds, and these storms will be more destructive, last longer and make landfall more frequently than in the past. Because this phenomenon is strongly associated with sea surface temperatures, it is reasonable to suggest a strong probability that the increase in storm intensity and climate change are linked." The mistake is in the "because" phrase. Since sea temperature and air temperature are not perfectly correlated, high sea temperature will correlate with a high difference between sea and air temperature. So the evidence doesn't tell us whether it is the sea temperature or the temperature difference that is related to storm intensity. This one is interesting partly because it echoes a famous error in economics. The Phillips Curve showed an inverse relation between inflation and unemployment--suggesting that by accepting some level of inflation one could hold down unemployment. When the attempt was made, it didn't work (hence "stagflation") because the real relation was not with the inflation level but the difference between the actual and anticipated level--and once a country maintained an inflation rate of (say) 5% for a while, people came to anticipate it, and the unemployment rate went back up.
64. dvaytw at 03:50 AM on 12 November, 2012
    Curious if anyone's heard of this fellow and his paper on worldwide hurricane activity: http://www.leshatton.org/wp-content/uploads/2012/01/HurricaneActivity1946-2010.pdf Best I can tell, he's not actually a climate scientist and his paper isn't actually peer-reviewed, but Google his research links to about a thousand denier sites.
65. Klaus Flemløse at 07:39 AM on 19 December, 2012
    Hurricanes Worldwide 1970-2012
    Based on data from Maue, RN (2011): Global Frequency . I have studied the development of the number of tropical cyclones during the years January 1970 through September 2012 divided into the Northern and Southern Hemisphere. I would like to thank R.N. Maue for collecting data on tropical cyclones and making data public.
    The reason why I have made this analysis is that there have been mistrust in the climate skeptical world to the predictions made by IPCC, and using the data from R.N. Maue it should be possible retrospectively to verify or falsify the prediction made using elementary statistical tools. In addition to this, I was not aware of the differences found below between the Northern and Southern Hemisphere.
    The following graph shows the development of the number of tropical cyclones for the years January 1970 through September 2012.
    
    Please use zoom to see details.
    The number of Major Hurricanes is significantly growing in the Northern Hemisphere and the Southern Hemisphere, while the Tropical Storms are significantly decreasing in the Southern Hemisphere.
    This is in line with IPCC’s prediction of increasing number of Major Hurricanes and a decreasing number of Tropical Storms.
    Since hot sea water is the fuel for tropical cyclones, I understand why we will see an increasing number of Major Hurricanes. But I do not understand why the number of Tropical Storm is expected to decrease in the future as they already have done.
    There is a positive correlation between then number of Tropical Storm, Hurricane and Major Hurricane within the Northern Hemisphere and the Southern Hemisphere respectively.
    If you look at a shorter time span than 43 years, other observations could be made. For the years 2009-2012 the number of tropical cyclones is smaller than expected. However, 4 years are a too few years to put forwards a statement on a general trend. Please be aware that 2012 only includes 9 month so far.
    There is an apparent difference in the development of the number of tropical cyclones in the Northern and Southern Hemisphere. There is more tropical cyclone in the Northern Hemisphere, approx. 68% out of the total number of tropical cyclones.
    The following picture shows some of the differences between the Northern and Southern Hemisphere in respect of tropical cyclones:
    
    The tropical cyclone prone area is much large in Northern Hemisphere than in the Southern Hemisphere.
    When you look at number of Major Hurricanes per month, it appears that there is a remarkable difference in their distribution per month. In the following graph, I have shifted the month to produce frequency distribution by season.
    
    The number of Major Hurricanes for the Northern Hemisphere shows a left skew distribution with a gradually decreasing trend after the peak at the month of September, while the number of Major Hurricanes for the Southern Hemisphere shows a more abrupt decreasing trend after the peak at the month of March.
    The tropical cyclone season is 12 months for the Northern Hemisphere and 9 months for the Southern Hemisphere.
    There is a 6 and 12 month cyclic variation in the number of tropical cyclones. This follows from the seasonal shift between the Northern and Southern Hemisphere and from a spectral analysis not shown here. The following graph shows the number of Tropical Storms worldwide for the years 2000-2012 by month:
    
    I have used a generalized linear model with a linear trend and two harmonic terms with a cycle and 6 and 12 month to respectively in order to produce the graph above.
    Please use zoom to see details.
    The variation originates from merging the figures from the Northern and Southern Hemisphere, each with its own cyclic variations. The model explains 65% of the total variation. There is no significant trend and approx. 87 Tropical Storms are expected annually.
    In total the number of tropical cyclones in the Southern Hemisphere makes up 32% of the total number of tropical cyclones.
    The tropical cyclones prone area in the Southern Hemisphere makes up 42% of the total tropical cyclones prone area. This number is found by counting 5 * 5 degree squares on the map page 505 Marine Safety Information Chapter 35 Tropical Cyclones where tropical cyclones occur. As a first guess, this is probably OK to do so, but a better estimate is wanted.
    The number of tropical cyclones in the Southern Hemisphere, calculated in proportion to tropical cyclone prone area, equals 0.42*6690= 2803. The actual number is 2134. This is significantly lower.
    This leads to the following questions? 1) Why is the tropical cyclones prone area smaller in the Southern Hemisphere than in the Northern Hemisphere?
    2) Why is the number of tropical cyclones in the Southern Hemisphere in proportion to area smaller than the in the Northern Hemisphere?
    3) Are these findings in line with IPCC’s predictions?
    Atlantic cyclones - biased information As a result of the dominance of US based news media worldwide, the information about the tropical cyclones in the Atlantic region is more dominant than from the other parts of the world. This can lead to an incorrect understanding of trends and causes, since the number of tropical cyclones in the Atlantic region accounts for only 12.6% of the total number of tropical cyclones. The Atlantic Tropical Storms, Hurricanes and Major Hurricanes accounts only for 13.1 %, 12.7 % and 10.8 % of the total number of Tropical Storms, Hurricanes and Major Hurricanes respectively.
    More details can be found in the statistical analysis of tropical cyclone data from R.N.Maue Worldwide Hurricane analysis.
66. citizenschallenge at 02:34 AM on 23 March, 2013

    Seems like this thread is in need of some updating.

    Here's the most recent news :

    ~ ~ ~ ~ ~ ~ ~ 

    Recent intense hurricane response to global climate change
    Greg Holland, Cindy L. Bruyère  |  March 2013,

    http://link.springer.com/article/10.1007%2Fs00382-013-1713-0

    Abstract
    An Anthropogenic Climate Change Index (ACCI) is developed and used to investigate the potential global warming contribution to current tropical cyclone activity. The ACCI is defined as the difference between the means of ensembles of climate simulations with and without anthropogenic gases and aerosols. This index indicates that the bulk of the current anthropogenic warming has occurred in the past four decades, which enables improved confidence in assessing hurricane changes as it removes many of the data issues from previous eras. We find no anthropogenic signal in annual global tropical cyclone or hurricane frequencies.

    But a strong signal is found in proportions of both weaker and stronger hurricanes: the proportion of Category 4 and 5 hurricanes has increased at a rate of ~25–30 % per °C of global warming after accounting for analysis and observing system changes.

    This has been balanced by a similar decrease in Category 1 and 2 hurricane proportions, leading to development of a distinctly bimodal intensity distribution, with the secondary maximum at Category 4 hurricanes.

    This global signal is reproduced in all ocean basins. The observed increase in Category 4–5 hurricanes may not continue at the same rate with future global warming. The analysis suggests that following an initial climate increase in intense hurricane proportions a saturation level will be reached beyond which any further global warming will have little effect.

    Full article: http://link.springer.com/article/10.1007/s00382-013-1713-0/fulltext.html

67. Richard Lawson at 18:52 PM on 9 September, 2013

    Klaus @ 65, I think yet the answer to your questions 1 and 2 is to be found in the Sea Surface Temperature. This map of SST shows that the hurricanes appear, as expected, in the warmest areas :

    Response:

    [DB] Reduced image width to 450.  Click on image for larger version.

68. UncleBucket at 22:56 PM on 22 March, 2014

    A new denialist argument that I'm seeing more and more is that because the USA experienced fewer hurricanes in 2013 than in some previous years, global warming has stopped or is disproven!

69. Daniel Bailey at 01:03 AM on 23 March, 2014

    That is such a collossal disconnect in logic that words fail me...

70. Klaus Flemløse at 06:45 AM on 23 March, 2014

    My analysis of the number of tropical storms only covers the period 1970-2012. This is the weak point, as far as I do not have data going back further. Therefore, I do not know if the development is caused by natural variations or if it is a result of the global warming. However the development is in line with the expectation from the global warming.

71. MA Rodger at 20:25 PM on 23 March, 2014

    The graph of North Atlantic cyclone numbers in the post could do with updating. The 10-year average has concinued to rise and now sits above 16 per year.

    

    N Atlantic hurricane numbers & major hurricane (catagory 3+) numbers have also risen but less dramatically and have presently their own little "hiatus." Add the argument about unreliable data prior to the 1970s, and it is difficult to establish with any certainty an AGW signal above the 'natural cycles'. The same goes for N Atlantic Accumulated Cyclone Energy (see here - usually 2 clicks to 'download your attachment').

    Globally, beyond the N Atlantic,  the data is even less reliable prior to 1970 (as Klaus Flemløse @70 would likely agree). So that Atlantic tropical cyclone graph is a bit of a rare beast.

72. SingletonEngineer at 16:19 PM on 11 September, 2017

    This is in response to the unfolding disasters in the Carribean and Florida and the fact that this thread is a little out of date.

    Recent relevant update from NOAA:

    https://www.gfdl.noaa.gov/global-warming-and-hurricanes/

    It seems that fresh data and recent analysis haven't changed things much.

73. SingletonEngineer at 16:24 PM on 11 September, 2017

    On further reflection, it appears that NOAA is suggesting that frequency is essentially constant and intensity is (may be?) increasing over time.

74. John Hartz at 23:45 PM on 11 September, 2017

    The article linked to by SingletonEngineer has been repeatedly cited and linked to by more than one mainstream climate scientist who has been interviewed by the media about the climate change-hurricane* connection in recent articles about Hurricanes Harvey, Irma, Jose, and Katia.

    Global Warming and Hurricanes: An Overview of Current Research Results posted on the website of NOAA’s Geophysical Fluids Dynamics Laboratory (GFDL). It was last revised on Aug 30, 2017.

    *North Atlantic basin only.

75. John Hartz at 02:38 AM on 12 September, 2017

    Over the past couple of weeks, I have posted links to the following articles about the climate change-hurricane connection on the SkS Facebook page.

    Did Climate Change Intensify Hurricane Harvey? by Robinson Meyer, The Atlantic, Aug 27, 2017

    Climate change did not “cause” Harvey, but it’s a huge part of the story by David Roberts, Energy & Environment, Vox, Aug 28, 2017

    Could Hurricane Harvey Deal A Fatal Blow To Climate Change Skepticism? by Jared Keller, Pacific Standard, Aug 28, 2017

    Harvey Shows How Planetary Winds Are Shifting by Eric Roston, Bloomberg News, Aug 30, 2017

    Does Harvey Represent a New Normal for Hurricanes? by Robinson Meyer, The Atlantic, Aug 29, 2017

    Katrina. Sandy. Harvey. The debate over climate and hurricanes is getting louder and louder by Chris Mooney, Energy & Environment, Washington Post, Aug 30, 2917

    What Hurricane Harvey says about risk, climate and resilience by Andrew Dressler, Daniel Cohan & Katharine Hayhoe. The Conversation US, Sep 1, 2017

    Three things we just learned about climate change and big storms: Can the lessons of Harvey save us? by Paul Rosenberg, Salon, Sep 4, 2017

    Denying Hurricane Harvey’s climate links only worsens future suffering by Dana Nuccitelli, Climate Consensus - the 97%, Guardian, Sep 5, 2017

    Harvey and climate change: why it won't change minds by Amy Harder, Axios, Sep 5, 2017

    Hurricane Harvey's aftermath could see pioneering climate lawsuits, Analysis by Sebastien Malo, Thomson Reuters Foundation, Sep 5, 2017

    On Climate, Hurricanes, And Growth by Joseph Majkut, Niskanen Center, Aug 31, 2017

    First Harvey, now Irma. Why are so many hurricanes hitting the U.S.? by Nisikan Akpan, PBS News Hour, Sep 6, 2017

    The science behind the U.S.’s strange hurricane ‘drought’ — and its sudden end by Chris Mooney, Energy & Environment, Washington Post, Sep 7, 2017

    Hurricane Irma is one of the most powerful Atlantic hurricanes ever: what we know by Brian Resnick, Science & Health, Vox, Sep 7, 2017

    6 Questions About Hurricane Irma, Harvey and Climate Change by Sabrina Shankman, InsideClimate News, Sep 6, 2017

    President Trump, hurricanes Harvey and Irma are sending you a message, Opinion by Andrés Oppenheimer, Miami Herald, Sep 7, 2017

    What We Know about the Climate Change–Hurricane Connection by Michael E. Mann, Thomas C. Peterson & Susan Joy Hassol, Scientific American, Sep 8, 2017

    As Hurricanes Irma and Harvey Slam the U.S., Climate Deniers Remain Steadfast by Marianne Lavelle, InsideClimate News, Sep 8, 2017

    Ask the Experts: How Did 2 Such Powerful Hurricanes Occur Back to Back? by Annie Sneed, Scientific American, Sep 7, 2017

    Another Way Climate Change Might Make Hurricanes Worse by Faye Flam, Bloomberg News, Sep 8, 2017

    Will Irma Finally Change the Way We Talk About Climate? by David Wallace-Wells, Daily Intelligencer, New York Magazine, Sep 9, 2017

    Irma and Harvey lay the costs of climate change denial at Trump’s door by Bob Ward, The Observer/Guardian, Sep 9, 2017

    Hurricane Irma Linked to Climate Change? For Some, a Very ‘Insensitive’ Question. by Lisa Friedman, Climate, New York Times, Sep 11, 2017

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