Yes, hurricanes are bad things when they kill and injure people, destroy property, and saturate the soil with seawater. But hurricanes are in the category of “stuff happens”.
Contrary to the true believers in catastrophic anthropogenic global warming (CAGW), hurricanes — and more inclusively, tropical cyclones — are not the fault of human beings. Tropical cyclones are not nature’s “retribution” for mankind’s “sinful” ways, such as the use of fossil fuels.
Note: If you wish to skip to the bottom line, scroll down to “Tropical Cyclone Activity — by the Numbers”.
RELEVANT RESEARCH
How do I know that tropical cyclones are not caused by human activity? Because there are people who actually look at the numbers. See, for example, “Hate on Display: Climate Activists Go Bonkers Over #Irma and Nonexistent Climate Connection” by Anthony Watts (Watts Up With That?, September 11, 2017). See also Michel de Rougement’s “Correlation of Accumulated Cyclone Energy and Atlantic Multidecadal Oscillations” (Watts Up With That?, September 4, 2017).
M. de Rougemont’s post addresses accumulated cyclone energy (ACE):
The total energy accumulated each year by tropical storms and hurricanes (ACE) is also showing such a cyclic pattern.
NOAA’s Hurricane Research Division explanations on ACE: “the ACE is calculated by squaring the maximum sustained surface wind in the system every six hours (knots) and summing it up for the season. It is expressed in 104 kt2.” Direct instrumental observations are available as monthly series since 1848. A historic reconstruction since 1851 was done by NOAA (yearly means).
Figure 2 Yearly accumulated cyclone energy (ACE) ACE_7y: centered running average over 7 years
A correlation between ACE and AMO [Atlantic Multidecadal Oscillation] is confirmed by regression analysis.
Figure 3 Correlation ACE=f(AMO), using the running averages over 7 years. AMO: yearly means of the Atlantic Multidecadal Oscillations ACE_7y: yearly observed accumulated cyclone energy ACE_calc: calculated ACE by using the indicated formula.
Regression formula:
Thus, a simple, linear relation ties ACE to AMO, in part directly, and in part with an 18 years delay. The correlation coefficient is astonishingly good.
Anthony Watts adds fuel to this fire (or ice to this cocktail) in “Report: Ocean Cycles, Not Humans, May Be Behind Most Observed Climate Change” (Watts Up With That?, September 15, 2017). There, he discusses a report by Anastosios Tsonis, which I have included in the list of related readings, below:
… Anastasios Tsonis, emeritus distinguished professor of atmospheric sciences at the University of Wisconsin-Milwaukee, describes new and cutting-edge research into natural climatic cycles, including the well known El Nino cycle and the less familiar North Atlantic Oscillation and Pacific Decadal Oscillation.
He shows how interactions between these ocean cycles have been shown to drive changes in the global climate on timescales of several decades.
Professor Tsonis says:
We can show that at the start of the 20th century, the North Atlantic Oscillation pushed the global climate into a warming phase, and in 1940 it pushed it back into cooling mode. The famous “pause” in global warming at the start of the 21st century seems to have been instigated by the North Atlantic Oscillation too.
In fact, most of the changes in the global climate over the period of the instrumental record seem to have their origins in the North Atlantic.
Tsonis’ insights have profound implications for the way we view calls for climate alarm.
It may be that another shift in the North Atlantic could bring about another phase shift in the global climate, leading to renewed cooling or warming for several decades to come.
These climatic cycles are entirely natural, and can tell us nothing about the effect of carbon dioxide emissions. But they should inspire caution over the slowing trajectory of global warming we have seen in recent decades.
As Tsonis puts it:
While humans may play a role in climate change, other natural forces may play important roles too.
Most recently, in a (paywalled) article at The Wall Street Journal, James Freeman quotes some federal government experts:
In May of this year, the federal government’s Climate.gov website published an article with the highly relevant title, “Can we detect a change in Atlantic hurricanes today due to human-caused climate change?”
Authors Chris Landsea, head of the tropical analysis and forecast branch at the federal National Hurricane Center in Miami, and Tom Knutson, senior scientist at the government’s Geophysical Fluid Dynamics Laboratory in Princeton, N.J., concluded:
Atlantic hurricanes display distinct busy and quiet periods: Busy hurricane decades occurred in the late 19th century, mid-20th century, and from the mid-1990s onward, but quieter decades in the early 20th century and in the 1970s to early-1990s.
These multi-decadal variations in Atlantic tropical storms and hurricanes have been linked to a phenomenon called the Atlantic Multidecadal Variability, which may be primarily natural internal variability or aerosol-driven.
A detectable greenhouse gas-induced influence on observed Atlantic tropical storm and hurricane behavior to date is difficult to identify because of the 50-80 year variability in hurricane activity.
The bottom-line answer to the question in the title is: No, we cannot confidently detect a trend today in observed Atlantic hurricane activity due to man-made (greenhouse gas-driven) climate change. Some human influence may be present though still below the threshold for confident detection.
As readers can imagine, trying to put such events in appropriate perspective amid a media hysteria can be a challenging task. Climate-obsessed reporters often cast weather events as unprecedented and record-breaking. Last year Mr. Landsea and National Hurricane Center colleague Eric Blake wrote a blog post with the following headline:
Was 2020 a Record-Breaking Hurricane Season? Yes, But. . .
The authors noted:
The 30 named storms in 2020 sets a record going back to the 1870s when the U.S. Signal Service (a predecessor to the National Weather Service) began tracking tropical storms and hurricanes. The only year that comes close is 2005 with 28 named storms. It’s also apparent that a very large increase has occurred in the number of observed named storms from an average of 7 to 10 a year in the late 1800s to an average of 15 to 18 a year in the last decade or so – a doubling in the observed numbers over a century!
They also added some additional useful context:
However, the number of named storms is only one measure of the overall measure of a season’s activity. And indeed, for the 2020 season, other measures of Atlantic tropical storm and hurricane activity were not record breaking. For example, the number of hurricanes (14) was well above average, but fell short of the previous record of 15 hurricanes that occurred in 2005.
For overall monitoring of tropical storm and hurricane activity, tropical meteorologists prefer a metric that combines how strong the peak winds reached in a tropical cyclone, and how long they lasted – called Accumulated Cyclone Energy or ACE. By this measure, 2020 was extremely busy, but not even close to record breaking. In fact, with a total ACE of 180 units, 2020 was only the 13th busiest season on record since 1878 with seasons like 1893, 1933, 1950, and 2005 substantially more active than 2020. One can also see that while there is a long-term increase in recorded ACE since the late 1800s, it’s quite a bit less dramatic than the increase seen with named storms. There also is a pronounced busier/quieter multi-decadal (40- to 60-year) cycle with active conditions in the 1870s to 1890s, late 1920s to 1960s, and again from the mid-1990s onward. Conversely, quiet conditions occurred in the 1900s to early 1920s and 1970s to early 1990s.
Perhaps media outlets should focus on simply reporting what happened, rather than promoting pet theories about why things happen.
THE BELIEF IN CAGW — AND AGW — RESTS ON DEEPLY FLAWED DATA AND METHODS
There are other reasons to be skeptical of CAGW, and even of AGW. For one thing, temperature records are notoriously unreliable, especially records from land-based thermometers. (See, for example, these two posts at Watt’s Up With That?: “Press Release – Watts at #AGU15 The Quality of Temperature Station Siting Matters for Temperature Trends” by Anthony Watts on December 17, 2015, and “Ooops! Australian BoM Climate Readings May Be invalid Due To Lack of Calibration“, on September 11, 2017.) And when those records aren’t skewed by siting and lack-of-coverage problems, they’re skewed by fudging the numbers to “prove” CAGW. (See my page, “Climate Change“.) Moreover, the models that “prove” CAGW and AGW are terrible, to put it bluntly. (Again, see “Climate Change“, and also Dr. Tim Ball’s post of September 16, 2017, “Climate Models Can’t Even Approximate Reality Because Atmospheric Structure and Movements are Virtually Unknown” at Watts Up With That?).
TROPICAL CYCLONE ACTIVITY — BY THE NUMBERS
As it happens, the Tropical Meteorology Project at Colorado State University maintains data sets for tropical cyclone activity in all six ocean basins as far back as 1971. (Some series begin with 1980, but I had archived data for earlier years before its removal.)
Here, courtesy of the Tropical Meteorology Project, is NOAA’s reconstruction of ACE in the North Atlantic basin through the 2021 season, which, if anything, probably understates ACE before the early 1960s:
It’s certainly doubtful that NOAA’s reconstruction of ACE is accurate and consistent as far back as 1851. I hesitate to give credence to a data series that predates the confluence of satellite observations, ocean-buoys, and specially equipped aircraft. The history of weather satellites casts doubt on the completeness of estimates for any period preceding the early 1960s.
The recent spikes in ACE are not unprecedented. And there are many prominent spikes that predate the late-20th-century temperature rise on which “warmism” is predicated. The trend from the late 1800s to the present is essentially flat. And, again, the numbers before the early 1960s must understate ACE.
Moreover, the metric of real interest is global cyclone activity; the North Atlantic basin is just a sideshow. Consider this graph of the annual values of ACE from 1980 through 2021:
Source: This page at the Tropical Meteorology Project at Colorado State University.
Here’s a graph of stacked (cumulative) totals for each of the six ocean basins for 1971 through 2021:
Note: There are slight discrepancies between the summations of ACE across basins and the global totals shown in the preceding graph.
The red line is the sum of ACE for all six basins, including the Northwest Pacific basin; the yellow line in the sum of ACE for the next five basins, including the Northeast Pacific basin; etc.
I have these observations about the numbers represented in the preceding graphs:
If one is a believer in CAGW (remember, the G stands for global), it is a lie (by glaring omission) to focus on random, land-falling hurricanes hitting the U.S. or other parts of the Western Hemisphere
The overall level of activity is practically flat from 1971 through 2021, with the exception of spikes that coincide with strong El Niño events.
There is nothing in the long-term record for the North Atlantic basin, which is probably understated before the early 1960s, to suggest that global activity in recent decades is unusually high.
I am very sorry for the victims of Ian and every weather-related disaster — and every disaster, whether man-made or not. But I am not about to reduce my “carbon footprint” because of the Luddite hysterics who dominate and cling to the quasi-science of climatology. In fact, the continued rise in atmospheric CO2 — which goes on despite dips and pauses in estimated of “global temperature” — seems to have nothing to do with CO2 emissions.
Some related reading:
Ron Clutz, “Temperatures According to Climate Models“, Science Matters, March 24, 2015
Dr. Tim Ball, “Long-Term Climate Change: What Is a Reasonable Sample Size?“, Watts Up With That?, February 7, 2016
The Global Warming Policy Foundation, Climate Science: Assumptions, Policy Implications, and the Scientific Method, 2017
John Mauer, “Through the Looking Glass with NASA GISS“, Watts Up With That?, February 22, 2017
George White, “A Consensus of Convenience“, Watts Up With That?, August 20, 2017
Jennifer Marohasy, “Most of the Recent Warming Could be Natural“, Jennifer Marohasy, August 21, 2017
Anthony Watts, “What You Need to Know and Are Not Told about Hurricanes“, Watts Up With That?, September 15, 2017
Anastasios Tsonis, The Little Boy: El Niño and Natural Climate Change, Global Warming Policy Foundation, GWPF Report 26, 2017
Anthony Watts, “Pielke Jr. – U.S. Tornado Damage Continues to Fall, 2018 Activity Near Record Lows“, Watts Up With That?, July 25, 2018
Roger Pielke, “No, Hurricanes Are Not Bigger, Stronger and More Dangerous“, Forbes, November 15, 2019
James Freeman, “Hurricane Ian and Climate”, The Wall Street Journal, September 30, 2022 (paywalled)