Weather

Global Warming Is Causing A LONG TERM in Tropical Cyclones – Rise for It?


Essay by Eric Worrall

The Australian researchers believe tornado intensity may be increasing, although their study is “too crude” to address this question.

Australian scientists identify global decline in tropical cyclones

ABC Weather / Via Ben Deacon

Tropical cyclones are less common around the world due to climate change, Australian scientists have found.

Main attractions:

  • Researchers have built a history of tropical cyclones around the world going back to the 1850s
  • They say tornadoes are becoming more intense due to climate change
  • Australia is experiencing about 11% fewer cyclones than it did in the 19th century

The team, led by Savin Chand from Federation University, found that tropical cyclones occur about 13% less frequently than in pre-industrial times.

Dr Chand said: “We are constantly seeing that tornado numbers are decreasing around the world.

However, the authors say their study only looked at the frequency of tropical cyclones, not their intensity, which they believe is increasing due to climate change.

Dr Chand said: “As the atmosphere warms, tropical cyclones form with more fuel for their severity.

“Although tornadoes will be less frequent, they will be more intense.”

Read more: https://www.abc.net.au/news/2022-06-28/cyclone-frequency-decline-worldwide-climate-change/101189558

Summary of the study;

Published:

Reducing the frequency of tropical cyclones in the context of global warming

Savin S. Chand, Kevin JE Walsh, Suzana J. Camargo, James P. Kossin, Kevin J. Tory, Michael F. Wehner, Johnny CL Chan, Philip J. Klotzbach, Andrew J. Dowdy, Samuel S. Bell, Hamish A. Ramsay & Hiroyuki Murakami

abstract

Evaluating the role of anthropogenic warming from temporally heterogeneous historical data with large natural variability has been difficult and has resulted in conflicting conclusions regarding the detection and analysis of human warming. complement the tropical cyclone trend (TC). Here, using reconstructed long-term representation of annual TC numbers together with high-resolution climate model tests, we show a strong downward trend in annual TC numbers. on a global and regional scale in the twentieth century. The dataset of the 20th Century Response Analysis (20CR) was used for reconstruction because compared to other reanalyses it only assimilated sea level pressure fields instead of using all available observations. available in the troposphere, making it less sensitive to temporal heterogeneity in observations. It can also reasonably capture TC signatures from the satellite era. Declining trends were found to be consistent with twentieth-century weakening of the Hadley and Walker cycles, making TC formation conditions less favorable.

Read more: https://www.nature.com/articles/s41558-022-01388-4

About tornado intensity;

… The 20CR results and high-resolution climate modeling results presented here show a clear downward trend in global and regional TC numbers between pre-industrial times and recent climates. than. The downward trend remains strong after accounting for the effects of natural climate change and aerosol effects on the North Atlantic and basin-specific biases in the 20CR data. It has been hypothesized that these changes were probably due to a 20th century weakening of the great tropical circulations, creating more hostile conditions for TC formation. These findings provide new insights that may help us trust future projections of fewer TCs associated with greenhouse warming.twelfth. Although the current reanalysis product decisions are too crude to draw conclusions about TC intensity, the general consensus from the observational record suggests an increase in the incidence of severe storms. important to anthropogenic warming.2. In the future, it is predicted that continued improvement in climate modeling and reanalysis products as well as in observational datasets could help identify anthropogenic climate change signals. on indicators such as TC intensity and amphibious activities. …

Read more: Same link as above

Summary of references 2 studies on increased storm intensity;

Tropical Cyclones and Climate Change Assessment: Part I: Detection and Distribution

Thomas Knutsonfirst, Suzana J. Camargo2, Johnny CL Chan3, Kerry Emanuel4, Chang-Hoi Ho5, James Kossin6, Mrutyunjay Mohapatra7, Masaki Satoh8, Masato Sugi9, Kevin Walshtenand Liguang Wu11

abstract

An assessment was made of whether detectable changes in tropical cyclone (TC) activity could be identified in observations and whether any changes could be human-caused climate change. Overall, historical data suggest that TC activity changes are detectable in some regions associated with TC tracking changes, while quality and quantity issues generate data. presents a greater challenge for analyzes based on TC intensity and frequency. Some specific conclusions have been published (case studies) about detectable anthropogenic effects on TCs that have been evaluated using a conventional approach that prefers avoidance of type I error (i.e. man-made detection or influence exaggeration). We conclude with at least low to moderate confidence that the polar migration observed at latitudes of maximum magnitude in the northwestern Pacific Ocean is detectable, or very abnormality from the expected natural variation. The authors’ opinions differed as to whether any of the observed TC changes demonstrated a clear human effect, or whether any other observed changes were representative of the observed human effects. whether the change is detectable or not. The issue was then refocused by evaluating evidence for detectable anthropogenic effects while seeking to reduce the risk of Type II errors (i.e., anthropogenic effects or detections). cause missing or missing). For this purpose, we used a much weaker “equilibrium of evidence” criterion for our assessment. This resulted in some of the more speculative TC findings and/or attribution claims, which we found to have a significant potential for false alarms (i.e. influence exaggeration or man-made findings). out) but can be useful for risk assessment. Some examples of these alternative statements, drawn from this approach, are presented in the report.

Read more: https://journals.ametsoc.org/view/journals/bams/100/10/bams-d-18-0189.1.xml

The “average confidence” of increased tornado intensity may not mean what you think. The IPCC vaguely defines mean confidence as 33-66% probability, likely not, although the wording of the definition is somewhat ambiguous. A much clearer definition of the term “average confidence” is the subject of the email Clipsgate 0967041809.txt, where Climate scientist Stephen Schneider enhanced the term “Mean Confidence” as a direct replacement for the term “Not Overarching”.


From: Stephen H Schneider <redacted>
To: redacted
Subject: Re: THC collapse
Date: Wed, 23 Aug 2000 10:43:29 -0700 (PDT)
Cc: Thomas Stocker <redacted>, Jerry Meehl <redacted>, 
Timothy Carter <redacted>, redacted, redacted, 
redacted, redacted, redacted, redacted, 
redacted, redacted, 
"Stouffer, Ron" <redacted>, redacted

Great Tom, I think we are converging to much clearer meanings across 
various cultures here. Please get the inconclusive out! By the way,
"possible" still has some logical issues as it is true for very large or
very small probabilities in principle, but if you define it clearly it is
probably OK--but "quite possible" conveys medium confidence better--but
then why not use medium confidence, as the 3 rounds of review over the
guidance paper concluded after going through exactly the kinds of
disucssions were having now. Thanks, Steve

On Wed, 23 Aug 2000 redacted wrote:

> 
> 
> Steve, I agree with your assesement of inconclusive --- quite possible is
> much better and we use 'possible' in the US National Assessment.  Surveys
> has shown that the term 'possible' is interpreted in this range by the
> public.
> 
> Tom
> 
> 
> 
> 
> Stephen H Schneider <redacted> on 08/23/2000 03:02:33 AM
>                                                               
>                                                               
>                                                               
>  To:      Thomas Stocker <redacted>           
>                                                               
>  cc:      Jerry Meehl <redacted>, Timothy Carter 
>           <redacted>, redacted,   
>           redacted, redacted,                 
>           redacted, redacted, 
>           Tom Karl/NCDC, redacted,                     
>           redacted, redacted,      
>           "Stouffer, Ron" <redacted>                      
>                                                               
>                                                               
>                                                               
>  Subject: Re: THC collapse                                    
>                                                               
> 
> 
> 
> 
> 
> 
> 
> 
> Hello all. I appreciate the improvement in the table from WG 1,
> particularly the inclusion of symmetrical confidence levels--but please
> get rid of the ridiculous "inconclusive" for the .34 to .66 subjective
> probability range. It will convey a completely differnt meaning to lay
> persons--read decisionmakers--since that probability range represents
> medium levels of confidence, not rare events. A phrase like "quite
> possible" is closer to popular lexicon, but inconclusive applies as well
> to very likely or very unlikely events and is undoubtedly going to be
> misinterpreted on the outside. I also appreciate the addition of
> increasing huricane intensities with warming moving out of the catch all
> less than .66 category it was in the SOD.
>   I do have some concerns with the THC issue as dealt with here--echoing
> the comments of Tim Carter and Thomas Stocker.  I fully agree that the
> likelihood of a complete collapse in the THC by 2100 is very remote, but
> to leave it at that is very misleading to policymakers given than there is
> both empirical and modeling evidence that such events can be triggered by
> phenomena in one century, but the occurrence of the event may be delayed
> a century or two more. Given also that the likelihood of a collapse
> depends on several uncertain parameters--CO2 stabilization level, CO2
> buildup rate, climate sensitivity, hydrological sensitivity and initial
> THC overturning rates, it is inconceivable to me that we could be 99% sure
> of anything--implied by the "exceptionally unlikely" label--given the
> plausibility of an unhappy combo of climate sensitivity, slower than
> current A/OGCMs initial THC strength and more rapid CO2 increase
> scenarios. Also, if 21st century actions could trigger 22nd century
> irreversible consequences, it would be irresponsible of us to not mention
> this possibility in a footnote at least, and not to simply let the matter
> rest with a very low likelihood of a collapse wholly within the 21st
> century.  So my view is to add a footnote to this effect and be sure to
> convey the many paramenters that are uncertain which determine the
> likelihood of this event.
>   Thanks again for the good work on this improtant table. Cheers, Steve
> 
> 
> On Wed, 23 Aug 2000, Thomas Stocker wrote:
> 
> > DEar Jerry, Tim and Ron et al
> >
> > I agree that an abrupt collapse - abrupt meaning within less than a
> decade, say
> > - has not been simulated by any climate model (3D and intermediate
> complexity)
> > in response to increasing CO2. Some models do show for longer
> integrations a
> > complete collapse that occurs within about 100-150 years. If you put that
> into
> > context of the apparent stability of THC during the last 10,000 years or
> so,
> > this is pretty "abrupt".
> >
> > Following up on the discussion regarding THC collapse, I think the
> statement Ron
> > apparently added to Ch9 needs to be made more specific. In order to keep
> Ch7 and
> > Ch9 consistent, I propose to Ron the following revision:
> >
> > "It seems that the likelihood of a collapse of the THC by year 2100 is
> less
> > than previously thought in the SAR based on the AOGCM results to date."
> >
> > There is really no model basis to extend this statement beyond 2100 as
> evidenced
> > by the figures that we show in TAR. There are many models that now run up
> to
> > 2060, some up to 2100, but very few longer.
> >
> > Also I should add for your information, that we add to Ch7 a sentence:
> >
> > "Models with reduced THC appear to be more susceptible for a
> > shutdown."
> >
> > Models indicate that the THC becomes more susceptible to collapse if
> previously
> > reduced (GFDL results by Tziperman, Science 97 and JPO 99). This is
> important as
> > "collapse unlikely by 2100" should not tempt people to conclude that THC
> > collapse is hence not an issue. The contrary is true: reduction means
> > destabilisation.
> >
> > Best regards
> >
> > thomas
> > --
> > ------------------------------------------------------------------
> > Thomas Stocker
> > Climate and Environmental Physics         redacted
> > Physics Institute, University of Bern     phone:  redacted
> > Sidlerstrasse 5                      NEW    fax:  redacted
> > 3012 Bern, Switzerland        http://www.climate.unibe.ch/~stocker
> > ------------------------------------------------------------------
> >
> 
> ------
> Stephen H. Schneider
> Dept. of Biological Sciences
> Stanford University
> Stanford, CA 94305-5020 U.S.A.
> 
> Tel: redacted
> Fax: redacted
> redacted
> 
> 
> 
> 
> 

------
Stephen H. Schneider
Dept. of Biological Sciences
Stanford University
Stanford, CA 94305-5020 U.S.A.

Tel: redacted
Fax: redacted
redacted

And of course, there’s the obvious question; If conditions are less favorable for cyclone formation, why are the already formed storms more intense? Wouldn’t unfavorable climatic conditions tend to slow down the formation and peak intensity of such cyclones? Why not increase low-to-moderate rainfall with crops?

Thermodynamics and the atmospheric water cycle must be in balance, but there seems to be no compelling reason to suggest that the balance must come in the form of an increase in extreme weather events around the world. .



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