Notes
About the Global Warming Policy Foundation 10
Executive summary
It is widely believed that hurricanes are getting worse as a consequence of climate change. This belief is fuelled by the media and some politicians, particularly when a bad storm occurs. This be- lief is reinforced because the damage caused by hurricanes is much greater nowadays, thanks to increasing populations in vulnerable coastal areas and greater wealth more generally.
But is this belief correct, or is it a misconception? This study has carefully analysed official data and assessments by hurricane scientists, and finds:
• 2021 and 2022 recorded the lowest number of both hurricanes and major hurricanes glob- ally for any two year period since 1980.
• The apparent long-term increase in the number of hurricanes since the 19th century has been due to changes in observational practices over the years, rather than a real increase.
• Data show no long-term trends in US landfalling hurricanes since the mid-19th century, when systematic records began, either in terms of frequency or intensity.
• Similarly, after allowing for the fact that many hurricanes were not spotted prior to the sat- ellite era, there are no such trends in Atlantic hurricanes either.
Globally there are also no trends in hurricanes since reliable records began in the 1970s.
Evidence is also presented that wind speeds of the most powerful hurricanes may now be overestimated in comparison to pre-satellite era ones, because of changing methods of meas- urement.
• The increase in Atlantic hurricanes in the last fifty years is not part of a long-term trend, but is simply a recovery from a deep minimum in hurricane activity in the 1970s, associated with the Atlantic Multidecadal Oscillation.
These findings are in line with those of hurricane scientists generally, as well as official bodies such as NOAA and the IPCC.
Geologists doing fieldwork in southeastern Utah’s Cedar Mountain Formation found carbon isotope evidence that the site, though on land, experienced the same early Cretaceous carbon-cycle change recorded in marine sedimentary rocks in Europe. This ancient carbon-cycle phenomenon, known as the ‘Weissert Event’ was driven by large, sustained volcanic eruptions in the Southern Hemisphere that greatly increased carbon dioxide levels in the atmosphere and produced significant greenhouse climate effects over a prolonged time.
Scientific research in recent decades has confirmed that major changes in the global carbon cycle caused significant changes in the Earth’s atmosphere and oceans 135 million years ago, during the early Cretaceous Period. A range of questions remain about the details of climate change dynamics in that era. This new research, involving wide-ranging chemical and radioactivity-based analyses of rock strata in Utah’s Cedar Mountain Formation, helps fill in that knowledge gap by confirming that such carbon-cycle shifts were recorded on land in ancient North America.
The carbon cycle is one of Earth’s fundamental environmental phenomena, involving the ongoing transfer of carbon among the atmosphere, oceans and living organisms, as well as soils, sediments and rocks in the solid Earth. The cycle is crucial to biological processes for living things on land and sea. When large-scale changes in the cycle occur, they can produce major shifts in climate and the oceans’ biological conditions.
“We’re studying how the global carbon cycle has functioned in the past, how changes are recorded in the sedimentary rocks around the world,” said Joeckel, a professor in the School of Natural Resources at Nebraska. The environmental phenomena he and his colleagues analyzed “are exactly the kind of things we’re talking about today, as people increase the input of carbon dioxide into the atmosphere at a much-accelerated rate by burning fossil fuels.”
Joeckel, the Nebraska state geologist, headed the Utah fieldwork and organized the study, published as a peer-reviewed paper in a special February issue of the journal Geosciences.
A recent paper (M. B. Freund et al 2023, MBF23 thereafter) in “Nature communication earth and environment” investigates the variability of the summer drought events since 1600. It uses the method of “stable isotope analyses C13/O18” to extend the “Standardised Precipitation-Evapotranspiration Index (SPEI) from 1950 to now back to 1600.
The paper describes and uses a multi proxy network over large parts of Europe (see Fig. 1 of MBF23) to reconstruct the history of summer droughts for a longer historic period. It finds interesting results about the dependency of those events on volcanos and solar forcing. It’s a worthwhile read and we were interested in whether the headline title is justified and likewise this claim in the Abstract:
“We show that the recent European summer drought (2015–2018) is highly unusual in a multi-century context…”
Thanks to the authors the used SPEI reconstruction annual data are available, so we were able to perform calculations to check these assertions.
An apparent first “confirmation” of the headline title of the paper appears in Figure 3a in MBH23:
Fig.1: A reproduction of Fig. 3a of MBH23. Annual European mean SPEI-data in blue/red, the low pass filter output is shown in black.
…
La géologie, une science plus que passionnante … et diverse
Fig.1: A reproduction of Fig. 3a of MBH23. Annual European mean SPEI-data in blue/red, the low pass filter output is shown in black.