Coastal flooding, wildfire and drought are all risks of concern due to global warming though the incidence of severe convective storms is not expected to change, a new report from Guy Carpenter & Company LLC suggests.
In the report — titled Global Warming: The Evolving Risk Landscape — Guy Carpenter warns the "most significant threat for coastal areas" is a rise in sea levels caused by melting glaciers and thermal expansion of ocean waters.
“Apart from this threat, changing weather patterns will impose drought and inland flood threats for many areas," according to the report. "As a general principle of climate change, some modification to the mean of meteorological extreme value distributions can be expected, but with a more concerning increase in tail thickness (or variability).
This change could amplify the effects of existing natural variability modes, such as the El Niño Southern Oscillation (ENSO), which already cause severe disruption due to flood, drought and hurricane frequency."
A rise in sea levels will cause "greater frequency and severity" of effects such as those produced by Hurricane Sandy, Guy Carpenter warned. Hurricane Sandy was downgraded to post-tropical storm status when it made landfall in New Jersey last October.
"Tropical cyclone, extratropical cyclone and tsunami coastal impacts will all come with greater frequency and severity under the projected sea-level rise," Guy Carpenter noted. "This poses a significant human and economic concern for these areas, and is a significant concern to the (re)insurance industry."
According to the report, the "incidence of severe convective storms is not expected to change under global warming" but Guy Carpenter added "more research is required" on such storms. Citing a 2007 article in the Proceedings of the Natural Academy of Sciences, Guy Carpenter noted "flooding under intense rainfall events has been shown to increase and will increase further under global warming.
That study used global climate models and a high-resolution regional climate model to look at meteorological conditions that cause severe thunderstorm formation in the United States. The authors predicted "a net increase during the late 21st century in the number of days in which these severe thunderstorm environmental conditions occur."
Guy Carpenter noted in its report that global climate models indicate that the number of days between precipitation events will increase for several areas including western North America.
"The effects on soil moisture could be particularly acute in the U.S. south central plains as well as southern Europe, raising significant issues for agricultural interests in these areas by the 2050s," according to the report. "Increasing periods between rainfall events places stress on soils, limiting the capacity for agricultural activity. In extreme cases, affected areas can essentially become deserts."
Wildfire risk is also a concern due to diminished snowpacks and diminished precipitation, Guy Carpenter noted.
“Fire probability is enhanced by warmer temperatures, lower relative humidities and greater wait times between rainfall events," according to the report. "As vegetation becomes dry under these conditions, it is more prone to ignition by random sources and more likely to spread with an increase in surrounding dry fuels. The wildfire hazard in areas already facing such a threat will see an increase in severity of this threat under global warming."