Motus Mentis

Here in New England we’re awaiting the arrival of Hurricane Henri. The original projections showed the center of the tracking cone passing right over us in Wellfleet, but now it looks as though the storm will make landfall somewhere in central Long Island. What we’ll get out here will be storm surge and wind, but probably a bit less rain than we were expecting before. (I’m just hoping the power stays on. We really should get a nice beefy Generac.)

Speaking of great swirling masses of hot air, I’ve no doubt that Henri will bring in its wake the usual gale of “extreme-weather” alarmism. For balance, then, I’ll offer a 2019 paper by Actual Climate Scientist Judith Curry.

The Executive Summary reads as follows:

This Report assesses the scientific basis for projections of future hurricane activity. The Report evaluates the assessments and projections from the Intergovernmental Panel on Climate Change (IPCC) and recent national assessments regarding hurricanes. The uncertainties and challenges at the knowledge frontier are assessed in the context of recent research, particularly with regards to natural variability. The following four questions frame this Report:

1. Is recent hurricane activity unusual?
In the North Atlantic, all measures of hurricane activity have increased since 1970, although comparably high levels of activity also occurred during the 1950’s and 1960’s. Geologic evidence indicates that the current heightened activity in the North Atlantic is not unusual, with a ‘hyperactive period’ apparently occurring from 3400 to 1000 years before present. Prior to the satellite era (1970’s), there are no reliable statistics on global hurricane activity. Global hurricane activity since 1970 shows no significant trends in overall frequency, although there is some evidence of a small increase in the number of major hurricanes.

2. Have hurricanes been worsened by manmade global warming?
Any recent signal of increased hurricane activity has not risen above the background variability of natural climate variations. At this point, there is no convincing evidence
that manmade global warming has caused a change in hurricane activity.

3. Have hurricane landfall impacts been worsened by manmade global warming?
Of recent impactful U.S. landfalling hurricanes, only the rainfall in Hurricane Harvey is unusual in context of the historical record. Warmer sea surface temperatures are
expected to contribute to an overall increase in hurricane rainfall, although hurricane-induced rainfall and flooding is dominated by natural climate variability. Storm surge risk is increasing slightly owing to the slow creep of sea level rise. The extent to which the recent increase in ocean temperatures and sea level rise can be attributed to manmade global warming is disputed. The primary driver for increased economic losses from landfalling hurricanes is the massive population buildup along coastlines.

4. How will hurricane activity change during the 21st century?
Recent assessment reports have concluded that there is low confidence in projections of future changes to hurricane activity. Any projected change in hurricane activity is
expected to be small relative to the magnitude of natural variability in hurricane activity.

Read the whole thing here.