Quote Originally Posted by Captdon View Post
Only four Cat 5 hurricanes have made landfall in the last 80 years.


Scientists cannot predict the likelihood of category 5 hurricanes making landfall in the U.S . That is largely a matter of chance. The statement below are from Yaleclimateconnections.org, "How

climate change is making hurricanes more dangerous"

In a 2015 paper using future model simulations, Knutson found an “increase in average cyclone intensity, precipitation rates, and the number and occurrence days of very intense category 4 and 5 storms.” Specifically, the simulations calculated a 28% increase in category 4 and 5 storms globally, with a 335% increase in the northeast Pacific and a 42% increase in the North Atlantic.
In Bhatia’s 2018 study, the intensity gains are even more alarming. The HiFLOR simulations project the number of major cyclones (category 3, 4, and 5) to increase by 20% globally and 29% in the Atlantic by 2081-2100. But HiFLOR suggests a significant increase in major systems even sooner.
The numbers really spike when isolating just category 5 storms, with an 85% global jump and 136% Atlantic basin leap. Of these findings, Bhatia says, “HiFLOR climate change experiments signal that tropical cyclones will more routinely reach wind speeds that are well above the category 5 threshold, hinting that the Saffir–Simpson scale might need to be extended to include higher categories in the early 21st century.
"There is a strong consensus in the tropical cyclone climate community that the incidence of high-category events will increase, and that storms will precipitate more,” Emanuel said. (Kerry Emanuel)

This is from the Geophysical Fluid Dynamics Lab and has a more conservative point of view regarding human involvement in affecting Atlantic hurricanes. Maybe the connection to AGW and intense hurricanes is overstated.


In summary, neither our model projections for the 21st century nor our analyses of trends in Atlantic hurricane and tropical storm activity support the notion that greenhouse gas-induced warming leads to large increases in either tropical storm or overall hurricane numbers in the Atlantic. While one of our modeling studies projects a large (~100%) increase in Atlantic category 4-5 hurricanes over the 21st century, we estimate that such an increase would not be detectable until the latter half of the century, and we still have only low confidence that such an increase will occur in the Atlantic basin, based on an updated survey of subsequent modeling studies by our and other groups. A recent study finds that the observed increase in an Atlantic hurricane rapid intensification metric over 1982-2009 is highly unusual compared to one climate model’s simulation of internal multidecadal climate variability, and is consistent in sign with that model’s expected long-term response to anthropogenic forcing. These climate change detection results for rapid intensification metrics are suggestive but not definitive, and more research is needed for more confident conclusions.

We also conclude that it is likely that climate warming will cause Atlantic hurricanes in the coming century have higher rainfall rates than present-day hurricanes, and medium confidence that they will be more intense (higher peak winds and lower central pressures) on average. In our view, it is uncertain how the annual number of Atlantic tropical storms will change over the 21st century. All else equal, coastal inundation levels associated with tropical cyclones should increase with sea level rise as projected for example by IPCC AR5. These assessment statements are intended to apply to climate warming of the type projected for the 21st century by prototype IPCC mid-range warming scenarios, such as A1B or RCP4.5.

Modelling studies:

Based on our published results and as well as those of other modeling groups, we conclude that at the global scale: a future increase in tropical cyclone precipitation rates is likely; an increase in tropical cyclone intensity is likely; an increase in very intense (category 4 and 5) tropical cyclones is more likely than not; and there is medium confidence in a decrease in the frequency of weaker tropical cyclones. Existing studies suggest a tropical cyclone windspeed increase of about 1-10% and a tropical cyclone precipitation rate increase of about 10-15% for a moderate (2 degree Celsius) global warming scenario. These global projections are similar to the consensus findings from a review of earlier studies in the 2010 WMO assessment. [There is already medium confidence for a detectable human contribution to past observed increases in heavy precipitation in general over global land regions and for the United States, although this increase has not been formally detected for hurricane precipitation alone.]