Judith Curry provides a sensible perspective on climate change

 Judith Curry is a renowned climate scientist who does not have an agenda.  She is a great source of information and opinion about climate.  Here is her latest blog entry "Assessment of climate change risk to the insurance sector".  The assessment provides a valuable perspective far beyond the insurance sector.

Some of the charts are striking - and show how disingenuous are some of the comments made by climate change alarmists, politicians, and the media.

Here is the link.

Here is her introduction

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The insurance sector is abuzz with a new report from AIR Worldwide on the insurance risk from the impact of climate change on hurricanes. Insurance industry clients of my company, Climate Forecast Applications Network (CFAN), have requested a critique of this report.

AIR Worldwide, a respected catastrophe risk modeling and consulting company, has recently published a report Quantifying the Impact from Climate Change on Hurricane Risk. AIR’s assessment has three components:

• Hazard component (relates to the frequency and intensity of events)
• Engineering component (relates to physical assets at risk)
• Financial component (relates to monetary losses)

The AIR Report purports to “capture the full range of plausible events that could impact an area.”

My critique focuses solely on the hazard component. A summary of my analysis is provided below:

• The driver for AIR’s assessment is warming associated with the emissions/concentration scenario RCP8.5, which AIR refers to as a ‘business as usual scenario.’ In fact, RCP8.5 is increasingly being judged as implausible by energy economists, and is not recommended for use in policy planning.

• The hurricane risk from climate change focuses on the number and intensity of U.S. landfalls in a changing climate. Their scenario of the number of major hurricanes striking the U.S. by 2050 is judged to be implausible for medium emissions scenarios such as RCP4.5.

• The sea level scenarios used in the AIR Report are higher than the recent IPCC consensus assessments and are arguably implausible for medium emissions scenarios.

• The AIR Report ignores the ‘elephant in the room’ that is of relevance to their target period to 2050: the Atlantic Multi-decadal Oscillation (AMO). A shift to the cool phase of the AMO would arguably portend fewer major hurricanes striking the U.S.

For reference on the topics of hurricanes, sea level and climate change, see these reports recently published by CFAN:

• Special Report on Sea Level and Climate Change [Download Report]
• Special Report on Hurricanes and Climate Change [link]

Here is her conclusion.

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Not surprisingly, the combination of implausibly high sea level rise projections and increase in the number of major hurricane landfalls in the U.S. results in a projection of substantial increases in damage and losses. From the AIR Report:

“The results of the analysis show that increased event frequency and sea level rise will have a meaningful impact on future damage. The growth in the number of stronger storms, and landfalling storms overall, increases modeled losses by approximately 20%, with slightly larger changes in areas such as the Gulf and Southeast coasts where major landfalls are already more likely today. The loss increases extend to inland areas as well, as stronger storms may penetrate farther from the coast.

The impacts from sea level rise, using the analysis of storm surge for New York, Miami, and Houston suggests that by 2050, sea level rise may increase storm surge losses by anywhere from one-third to almost a factor of two, with larger impacts possible when combined with increases in the number of major storms. The results suggest that an extreme surge event in today’s climate may be twice as likely to happen 30 years from now.”

While predictions for global climate change out to 2100 are weakly constrained and highly uncertain, we have a much better idea of the constraints on likely outcomes out to 2050. It is expected that variations in the Atlantic Multidecadal Oscillation will continue to dominate the statistics of Atlantic hurricanes for the next several decades, with any signal from global warming being difficult to discern amidst the natural variability.

The plausible worst case scenario has an important role to play in some decision making frameworks. However, the plausible worst case scenario requires assumptions that are justified and not falsifiable based on our background knowledge. The scenarios for climate change out to 2050 presented by AIR are based on an implausible emissions scenario that produces an implausible amount of warming by 2050. Even if this large amount of warming is accepted as plausible, the scenario for substantially increased numbers of major hurricane landfalls impacting the U.S. is judged to be very unlikely if not borderline implausible. The intermediate-high sea level rise scenario in the AIR Report extends well beyond the likely range of the most recent IPCC assessment, even for RCP8.5.

Apart from the slow creep of sea level rise which in recent decades has been tracking the low end of the RCP4.5 scenario, there is little justification for expecting a noticeable increase in insured losses associated with U.S. landfalling hurricanes by 2050.