Is Global Warming Increasing the
Severity and/or Frequency of Hurricanes?
Science Findings vs. Beliefs of Climate Deniers.
Cyclones in Pacific Ocean break records.
About the Saffir-Simpson hurricane category scale (a.k.a. the Saffir-Simpson Hurricane Wind Scale (SSHWS):
The severity of hurricanes is numbered on the Saffir-Simpson hurricane category scale. It currently extends only from Category 1 to 5, where Category 5 involves winds equal to or in excess of 156 mph or 251 km/hr. Some recent hurricanes have reached 185 and 190 mph. Some have suggested an expansion of the SSHWS scale to differentiate among the most severe storms.
Jim Williams wrote an article for Medium.com based upon discussions in the “Climate Change Discussion” and “Climate Change: It’s Personal” Facebook groups. He suggested an extended scale:
Category 1 storms have winds from 74 to 95 MPH (119 to 153 km/h).
Category 2 storms have winds from 96 to 110 MPH (154 to 177 km/h).
Category 3 storms have winds from 111 to 130 MPH (179 to 209 km/h).
Category 4 storms have winds from 131 to 155 MPH (211 to 249 km/h).
Category 5 storms have winds from 156 to 181 MPH (251 to 291 km/h)
Category 6 storms have winds from 182 to 207 MPH (293 to 333 km/h).
Category 7 storms have winds above 208 MPH (>335 km/h).1
Using the expanded scale, then Hurricanes:
"Labor Day" on 1935-SEP-03 with sustained winds at 185 mph,
"Camille" on 1969-AUG-17 at 190 mph,
"Allen" on 1980-AUG-05 at 190 mph,
"Gilbert" on 1998-SEP-13 at 185 mph,
"Wilma" on 2005-OCT-10 at 185 mph,
"Irma" on 2017-SEP-05 at 185 mph,
would all be Category 6 storms.
Is global warming increasing the severity and/or frequency of hurricanes?
According to Anne Sneed, writing for Scientific American:
"Many experts are confident that a warmer world will create stronger storms -- and already is doing so. Since 1981 the maximum wind speed of the most powerful hurricanes has risen, according to research by Jim Elsner, a climatologist at The Florida State University. 2 That’s because higher ocean heat provides more energy for storms, fueling their intensity. Hurricane Patricia, in 2015, set the record at the time for top wind speed -- 215 miles per hour -- in the north Atlantic. The next year Winston shattered records as the most intense cyclone in the Southern Hemisphere." 3
David Leonhardt, wrote an article for The New York Times about hurricane Harvey with the title: "The Storm That Humans Helped Cause." A better title might have been: "The Storm That Humans Made More Destructive."
He started his article by noting that the "... daily surface temperature of the Gulf of Mexico last winter [2016 - 2017] never dropped below 73º [F or 23ºC]." This is an all-time hottest value for the Gulf's minimum water temperature. He continued:
"This sort of heat has a specific effect on storms: Warmer weather causes heavier rainfall. Why? When the seas warm, more moisture evaporates into the air, and when the air warms ... it can carry more moisture.
The severity of Harvey, in other words, is almost certainly related to climate change. ..."
"[Climate change] has aggravated droughts, famines and deadly heat waves. In the United States, global warming seems to be contributing to the spread of Lyme disease."
" 'The heaviest rainfall events have become heavier and more frequent, and the amount of rain falling on the heaviest rain days has also increased,' as the National Climate Assessment, a federal report, found. 4 'The mechanism driving these changes,' the report explained, is hotter air stemming from 'human-caused [global] warming'. ..." 5
Leonhardt noted that Houston added 24% additional paving between 1996 and 2011. This adds to the probability of flooding because pavement does not absorb water the way that soil does. He ominously concludes:
"Add up the evidence, and it overwhelmingly suggests that human activity has helped create the ferocity of Harvey. That message may be hard to hear — harder to hear, certainly, than stories of human kindness that is now mitigating the storm’s toll. But it’s the truth.
Beyond Harvey, the potential damage from climate change is terrifying. Disease, famine and flooding of biblical proportions are within the realm of possibility. Unfortunately, stories of potential misery have not been enough to stir this country to action. They haven’t led to a Manhattan Project for alternative energy or a national effort to reduce carbon emissions.
So when we are faced with actual misery that stems in part from climate change, we should be honest about it.
What’s happening in Texas is heartbreaking, and yet it will be a more frequent part of modern life unless we do something about it." 5
Surveys of papers by climate scientists have indicated that: among those papers that specify a root cause of climate change, 97% agree that is primarily caused by human activity. A consensus of scientists also agree that climate change is the direct cause of the recent increased ferocity of hurricanes. Some scientists also believe that climate change is also increasing the frequency of hurricanes.
The Center for Climate and Energy Solutions (C2ES) in Arlington, VA is: "an independent, nonpartisan, nonprofit organization working to forge practical solutions to climate change." They stated:
"Although scientists are uncertain whether climate change will lead to an increase in the number of hurricanes, warmer ocean temperatures and higher sea levels are expected to intensify their impacts.
Recent analyses conclude that the strongest hurricanes occurring in some regions including the North Atlantic have increased in intensity over the past two to three decades. For the continental United States in the Atlantic Basin, models project a 45-87 percent increase in the frequency of Category 4 and 5 hurricanesdespite a possible decrease in the frequency of storms." 6
The United Nations IPPC report of 2018-OCT concludes that the ratio of the number of very high intensity to low intensity hurricanes (in the Northern Hemisphere) and cyclones (in the Southern Hemisphere) is probably increasing. 6 They stated:
"... we assess that under
3 to 4 °C of [global] warming it is more likely than not (medium confidence) that the global number of tropical
cyclones would decrease whilst the number of very intense cyclones would increase." 10
Category 5 hurricanes are currently the strongest storms in the Saffir-Simpson hurricane category scale. They have winds of 156 mph (251 km/h) or more. Such a large increase in the number of such hurricanes would increase the average hurricane intensity greatly.
In addition to the effects of climate change -- which will show a slow increase over decades in the strength of hurricanes -- there are some shorter-term cyclical changes that made hurricanes particularly severe during 2017:
The British Broadcasting Corporation (BBC) reports that three factors have increased the likelihood of hurricanes forming:
"A wetter and stronger monsoon [season] in West Africa."
"A natural cycle called the Atlantic Multi-Decadal Oscillation (AMO)" [which] has reached a peak this year." 7
This year has seen a lack of wind shear, a phenomenon that breaks up hurricanes. Some scientists believe that this is caused by the cyclical El Niño being at a neutral level -- neither high nor low -- at this time.
Kerry Emanuel, a leading atmospheric scientist at the Massachusetts Institute of Technology said:
"The number of hurricanes in the Atlantic varies a great deal from year to year for reasons that have to do with natural climate fluctuations like El Niño and also just plain random variability. A lot of it is just sheer chance. ..."
Hurricane Andrew in 1992, which was the most damaging of any US hurricane, occurred in a very quiet year.
That's just because the noise is so large and we are looking for these small signals. A busy year is no guarantee that you are going to see a major hurricane [make] landfall." 7
Professor Richard Allan from the Department of Meteorology at the University of Reading, UK, said:
"In terms of the factors that control the genesis and the intensification of these hurricanes, a number of these point to the fact that they will undoubtedly be slightly more severe due to the extra heat content in the ocean due to the long-term warming of the climate. ..."
"The evidence is that there is not really going to be an increase in the number of tropical cyclones but there is certainly some evidence that the strongest hurricanes will become more intense.
"In terms of the rainfall and the storm surges that's very strong evidence that the amount of rain that will fall out of these intense hurricanes will be greater and storm surges will be higher and more deadly." 7
2018-OCT-23, Hurricane Willa in the Pacific Ocean breaks a hurricane record:
Science News reported that Hurricane Willa broke an eastern and central Pacific storm season record. There have been 22 named storms in that area of the Pacific Ocean; half were Category 3 or stronger.
Carolyn Gramling, writing for Science News, referred to comments by Gerry Bell, research meteorologist at NOAA’s Climate Prediction Center in College Park, MD. He said that the eastern Pacific season has been:
"Very active. [But whether or not the 2018 season is a record-breaker] depends on how you classify it.
Bell developed "ACE," the Accumulated Cyclone Energy measure to compare cyclones. Its calculation includes both the intensity and duration of a storm. The current Pacific season already the highest ACE measurement on record. It continues until NOV-30.
Climate change deniers:
Some deniers are downplaying the information of the ferocity of the recent hurricanes, implying that climate change believers are trying to delude the public. For example:
Commenting on Hurricane Irma during 2017-SEP:
Columnist Ann Coulter, whose recent book is called "In Trump We Trust," tweeted:
"Hurricane update from Miami: Light rain; residents at risk of dying of boredom. 8
Radio show host, Rush Limbaugh, said that the media are following false data from climate scientists and assorted liberals and exaggerating the intensity of the hurricanes in order to increase the public's anxiety about climate change, He said:
"... there is a desire to advance this climate change agenda, and hurricanes are one of the fastest and best ways to do it. You can accomplish a lot just by creating fear and panic. ..."
"They are the ones using it to advance a political agenda, not me. And all I'm doing is pointing it out. 8
Leonard Pitts Jr., writing for the Miami Herald, said:
Last year, right-wing radio host Rush Limbaugh said that hurricanes are actually part of a vast liberal plot. 'It is in the interest of the left to have destructive hurricanes,' he said, 'because then they can blame it on climate change. ..."
"He ... [expressed the opinion] that media and marketers were in on the conspiracy, using hurricanes to drive viewership and sales of bottled water."
"Limbaugh’s lunacy reflects right-wing orthodoxy, which favors doing nothing in response to climate change on the theory it’s all an expensive boondoggle designed to victimize innocent oil and gas companies. So you get Trump pulling the country out of the Paris climate accord and Florida Governor Rick Scott forbidding his team to even use the term 'climate change.' Where the health of our planet is concerned, Republicans essentially ask us to make a wager that science is wrong." 9
The following information sources were used to prepare and update the above
essay. The hyperlinks are not necessarily still active today.
Jim Williams, "Evolving the Saffir-Simpson Hurricane Categories," Medium, 2017-SEP-14, at: https://medium.com/
James B. Elsner et al., "The increasing intensity of the strongest tropical cyclones," Florida State University, at: http://myweb.fsu.edu/
David Leonhardt, "Harvey, the Storm That Humans Helped Cause," The New York Times, 2017-AUG-29, at: https://www.nytimes.com/
"Hurricanes and Climate Change," Center for Climate and Energy Solutions, undated, at: http://www.c2es.org/
Matt McGrath, "Hurricanes: A perfect storm of chance and climate change?," BBC News, 2017-SEP-21, at: http://www.bbc.com/
Mike Snider, "Rush Limbaugh, Ann Coulter facing blowback on Hurricane Irma comments," USA Today, 2017-SEP-12, at: https://www.usatoday.com/
Leonard Pitts, Jr., "Hurricanes are not a liberal conspiracy, trust me on this one," Miami Herald, 2017-SEP-09, at: http://www.miamiherald.com/
"Impacts of 1.5ºC global warming on natural and human systems," Intergovernmental Panel on Climate Change, 2018, Chapter 3, Box 3-47, Line 18, at: http://www.ipcc.ch/ This report has a notice on every page to "Not Cite, Quote or Distribute." They also note that the report is "subject to correction, copy-editing, and layout." However, the editor of this essay on the ReligiousTolerance.org web site feels that a very brief quotation is compatable with copyright law and the best interest of people who read this essay.
Carolyn Gramling, "Hurricane Willa breaks an eastern and central Pacific storm season record," Science News, 2018-OCR-23, at: https://www.sciencenews.org/