Frequency of U.S. Hurricanes Not Increasing: Hurricane Experts (Graphs)

Researchers: Hurricanes are NOT increasing in frequency nor intensity, data shows. Increase in hurricane damage is due to more people living along the U.S. coastline.

MAIN POINTS from a 2018 research article from the American Meteorological Society: “While neither U.S. landfalling hurricane frequency nor intensity shows a significant trend since 1900, growth in coastal population and wealth have led to increasing hurricane-related damage along the U.S. coastline,” indicates the research. It also explained: Since 1900 neither observed CONUS [Continental United States] landfalling hurricane frequency nor intensity show significant trends, including the devastating 2017 season. [T]here is an insignificant trend in CONUS landfalling hurricanes from 1900-2017 (Fig. 2a)…[and] (Fig.2b). We therefore conclude that the large increase in observed hurricane-associated inflation-adjusted CONUS damage (Pielke et al. 2008) is primarily due to increases in exposure as opposed to increasing frequency or intensity of hurricanes making CONUS landfall.

HIGHLIGHTS OF THE STUDY: – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – The 2018 peer-reviewed scientific manuscript examined the trends in CONUS [Continental United States] landfalling hurricanes and was published in the Bulletin of the American Meteorological Society (BAMS). TITLE: Continental U.S. Hurricane Landfall Frequency and Associated Damage: Observations and Future Risks “While neither U.S. landfalling hurricane frequency nor intensity shows a significant trend since 1900, growth in coastal population and wealth have led to increasing hurricane-related damage along the U.S. coastline.” Via: ResearchGate’s early online release (Archive) Date: Aug. 15, 2017; Second Revision: 1 February 2018

Figures 2a and 2b: The dotted lines represent linear trends over the period. Pages 36-37: Figures 2a and 2b: “Fig. 2. (a) CONUS landfalling hurricanes by year from 1900-2017 and (b) CONUS landfalling major hurricanes by year from 1900-2017. The dotted lines represent linear trends over the period. P-values for the linear trends are 0.33 (landfalling hurricanes) and 0.61 (landfalling major hurricanes) indicating that neither of these trends are significant.” – Page 4: [S]ince 1900 neither observed CONUS landfalling hurricane frequency nor intensity show significant trends, including the devastating 2017 season. Growth in coastal population and regional wealth are the overwhelming drivers of observed increases in hurricane-related damage. – Pages 5 – 6: [L]andfalling CONUS hurricanes have not increased in frequency or intensity since 1900 through 2017 (as shown below), meaning that an unbiased normalized loss record would be expected to show the same (lack of) trend. Independent climate and economic data indicate that the primary source of the increase in damage caused by hurricanes in recent decades is due to increases in exposure along the United States East and Gulf Coasts[.] – Pages 6-7: Data and Methodology CONUS hurricane landfall data are extracted from the Atlantic Oceanographic and Meteorological Laboratory’s (AOML) website from 1900-1960 and 1983-2016 (http://www.aoml.noaa.gov/hrd/hurdat/UShurrs_detailed.html). For the period from 1961-1982 where the National Hurricane Center’s (NHC’s) hurricane database (HURDAT2) reanalysis project (Landsea and Franklin 2013) is not yet complete, we calculated hurricane landfall locations directly from hurricane tracks plotted from HURDAT2 with landfall intensities constrained to be the same Saffir-Simpson scale category as listed on the AOML website: https://www.aoml.noaa.gov/hrd/hurdat/All_UnitedStates_Hurricanes.html. Landfall locations and intensities for the 2017 Atlantic hurricane season were taken from NHC operational advisories. Multiple landfalls by an individual TC were counted separately as long as they traveled over the open ocean for at least 100 miles between their individual landfalls. In the case of 2017, all three CONUS hurricanes (Harvey, Irma and Nate) made multiple landfalls, but the second landfall was less than 100 miles from the first one, and consequently, each storm was counted once in this analysis.” – Page 9: Trends in Continental United States Landfalling Hurricanes and Normalized Hurricane Damage … [T]here is an insignificant trend in CONUS landfalling hurricanes from 1900-2017 (Fig. 2a). When we only examine hurricanes that made landfall at major hurricane strength (Saffir-Simpson Category 3-5) (one-minute sustained winds >=96 kt), which are responsible for greater than 80% of all normalized tropical cyclone-related damage (Pielke and Landsea 1998), we find a similar insignificant trend (Fig. 2b). We therefore conclude that the large increase in observed hurricane-associated inflation-adjusted CONUS damage (Pielke et al. 2008) is primarily due to increases in exposure as opposed to increasing frequency or intensity of hurricanes making CONUS landfall. – Page 22: Discussion and Conclusions: We have investigated trends in CONUS hurricane activity since 1900 and found no significant trends in landfalling hurricanes, major hurricanes or normalized damage, consistent with what has been found in previous studies. Despite a lack of trend in observed CONUS landfalling hurricane activity since 1900, large increases in inflation-adjusted hurricane-related damage have been observed, especially since the middle part of the 20th century. We demonstrate that this increase in damage is due strongly to societal factors, namely increases in population and wealth along the US Gulf and East Coasts. – – – – – – – – – – – – – END OF HIGHLIGHTS – – – – – – – – – – – – –

WE CREATED GRAPHS TO SHOW THE DATA UP TO THE 2020s – We used a red line to indicate the trend of the hurricanes that have impacted the Continental United States (CONUS) each decade since 1900. – We used an updated version of the same data source used by the researches in the study: Hurricane Research Division – The National Oceanic & Atmospheric Administration (NOAA) (Archived)

Bjorn Lomborg tweeted on 11/18/2020: Best long-term data is US landfalling hurricanes, because reliably recorded since 1900 Frequency of all hurricanes *not* increasing Frequency of strongest hurricanes (Cat3+) *not* increasinghttps://t.co/FxxiSIZnGL pic.twitter.com/g6lvdcvs3d — Bjorn Lomborg (@BjornLomborg) November 18, 2020 Best long-term data is US landfalling hurricanes, because reliably recorded since 1900 Frequency of all hurricanes *not* increasing Frequency of strongest hurricanes (Cat3+) *not* increasing https://journals.ametsoc.org/bams/article/99/7/1359/70330/Continental-U-S-Hurricane-Landfall-Frequency-and

SOURCES: – The early online released by ResearchGate noted: “Early Online Release: …This preliminary version of the manuscript may be downloaded, distributed, and cited[.]” – The final research was published in the Bulletin of the American Meteorological Society: DOI: https://doi.org/10.1175/BAMS-D-17-0184.1 Page(s): 1359–1376 PDF: https://journals.ametsoc.org/view/journals/bams/99/7/bams-d-17-0184.1.xml?tab_body=pdf Full text: https://journals.ametsoc.org/view/journals/bams/99/7/bams-d-17-0184.1.xml?tab_body=fulltext-display Full citation: “Klotzbach, P., S. Bowen, R. Pielke, and M. Bell, 2018: Continental United States Hurricane Landfall Frequency and Associated Damage: Observations and Future Risks. Bull. Amer. Meteor. Soc. doi:10.1175/BAMS-D-17-0184.1, in press.

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