Roger, never a truer word was said: "We have often urged caution in over-interpreting tropical cyclone time series that begin in the 1970s and 1980s because it is well understood that this period represented a low point in activity. Starting an analysis in that period invariably will result in upwards trends in tropical cyclone activity. But start the same analysis in the decades before, and those trends are muted or disappear altogether."
In AR6's Summary for Policy Making, A.3.4, the following seemingly contradictory statements are made:
"It is likely that the global proportion of major (Category 3–5) tropical cyclone occurrence has increased over the last four decades, and it is very likely that the latitude where tropical cyclones in the western North Pacific reach their peak intensity has shifted northward; these changes cannot be explained by internal variability alone (medium confidence). There is low confidence in long-term (multi-decadal to centennial) trends in the frequency of all-category tropical cyclones. Event attribution studies and physical understanding indicate that human-induced climate change increases heavy precipitation associated with tropical cyclones (high confidence), but data limitations inhibit clear detection of past trends on the global scale."
So the IPCC cherry pick their opening statement by starting their analysis in the 1980s ('last four decades'). As Roger warns this presents an increasing trend that disappears when the full data set is considered which justifies the "low confidence in long-term (multi-decadal to centennial) trend."
Yesterday, University of Reading Professor, Ed Hawkins tried to pull me up on LinkedIn, by quoting just the first part of the above paragraph. When I replied with the full context, linking Roger in, I was blocked.
This recalls 2005, after Wilma. This was going to be new normal (2005 year). Then what happened?
If I have it right, 11 years + 10 mos consecutive without a cat 3 or higher hitting US coasts out of Atlantic basic as I recall.
If I'm not mistaken, that broke the old record for consecutive years in the basin without a "major", not by a month or a year but by about double (~6 years). Which had existed for around 100 years (since Galveston maybe?).
While the graphs don't seem to indicate this, I have to ask: is there any trend of increased volatility? As you may remember, last year I hypothesized that because CO2 generated in China or India might not reach the US for a year or so, this might imply greater variability in its effects even if the average stayed virtually the same. The analogy is to a glassmaking furnace in which there is great variability in composition until the tank becomes well-mixed.
Do climate models incorporate or account for ACE? How is ACE accounted for in global energy balances? Are you aware of on-going research that considers climate modeling from a strict energy balance perspective?
There are an increasing number of studies of precipitation from landfalling TCs. They show some mixed results related to trends and are subject to the same sort of challenges with respect to start and end dates, as we see with other TC studies. All such studies should be grounded in a mathematical and theoretical basis for what sorts of trends should be detectable at present, in the context of documented variability. The magnitude of changes projected by various climate models and summarized in the recent WMO assessments would not suggest detection is likely today.
Roger, never a truer word was said: "We have often urged caution in over-interpreting tropical cyclone time series that begin in the 1970s and 1980s because it is well understood that this period represented a low point in activity. Starting an analysis in that period invariably will result in upwards trends in tropical cyclone activity. But start the same analysis in the decades before, and those trends are muted or disappear altogether."
In AR6's Summary for Policy Making, A.3.4, the following seemingly contradictory statements are made:
"It is likely that the global proportion of major (Category 3–5) tropical cyclone occurrence has increased over the last four decades, and it is very likely that the latitude where tropical cyclones in the western North Pacific reach their peak intensity has shifted northward; these changes cannot be explained by internal variability alone (medium confidence). There is low confidence in long-term (multi-decadal to centennial) trends in the frequency of all-category tropical cyclones. Event attribution studies and physical understanding indicate that human-induced climate change increases heavy precipitation associated with tropical cyclones (high confidence), but data limitations inhibit clear detection of past trends on the global scale."
So the IPCC cherry pick their opening statement by starting their analysis in the 1980s ('last four decades'). As Roger warns this presents an increasing trend that disappears when the full data set is considered which justifies the "low confidence in long-term (multi-decadal to centennial) trend."
Yesterday, University of Reading Professor, Ed Hawkins tried to pull me up on LinkedIn, by quoting just the first part of the above paragraph. When I replied with the full context, linking Roger in, I was blocked.
Superb, Roger and Ryan.
This recalls 2005, after Wilma. This was going to be new normal (2005 year). Then what happened?
If I have it right, 11 years + 10 mos consecutive without a cat 3 or higher hitting US coasts out of Atlantic basic as I recall.
If I'm not mistaken, that broke the old record for consecutive years in the basin without a "major", not by a month or a year but by about double (~6 years). Which had existed for around 100 years (since Galveston maybe?).
While the graphs don't seem to indicate this, I have to ask: is there any trend of increased volatility? As you may remember, last year I hypothesized that because CO2 generated in China or India might not reach the US for a year or so, this might imply greater variability in its effects even if the average stayed virtually the same. The analogy is to a glassmaking furnace in which there is great variability in composition until the tank becomes well-mixed.
Do climate models incorporate or account for ACE? How is ACE accounted for in global energy balances? Are you aware of on-going research that considers climate modeling from a strict energy balance perspective?
Roger, would you be so kind to ruminate on the Biochar issue?
Not a topic I've got any expertise in, but I'll take a look
Is there an “accumulated precipitation” metric for TCs? Any opinion on how it would be trending?
There are an increasing number of studies of precipitation from landfalling TCs. They show some mixed results related to trends and are subject to the same sort of challenges with respect to start and end dates, as we see with other TC studies. All such studies should be grounded in a mathematical and theoretical basis for what sorts of trends should be detectable at present, in the context of documented variability. The magnitude of changes projected by various climate models and summarized in the recent WMO assessments would not suggest detection is likely today.
The NOAA hurricane records go back to about 1850. If 170 years is not enough data, how many years do we need to see?
A good point. Though the NOAA data is for the US, which is a small subset of global landfalls
"In 2022 there were 18 total landfalling tropical cyclones of at least hurricane strength around the world, of which 5 were major hurricanes."
Is this supposed to say 13 rather than 18? That's what is shown in the chart.
The 18 includes the 5. Sorry for the confusion.
Oh, of course. I should have realized. Thanks.
Have you sent a copy of this to Bill Nye, given his misconceptions on the subject?
He'd probably annotate it with a sharpie ;-)