Hurricane Florence threatening the US coast

13/09/2018 - Hurricane Florence is threatening the US coast as it will likely hit North or South Carolina. Last year already brought unusually devastating tropical cyclones.
Hurricane Florence threatening the US coast
The strongest tropical cyclones in the satellite record (since 1979). Data from Velden, Olander,Herndon & Kossin, Mon. Weather Rev 2017. Background: map of historical tropical cyclone tracks, by Robert Rohde

On this issue, Stefan Rahmstorf, Chair of Earth System Analysis at the Potsdam Institute for Climate Impact Research and Professor at the University of Potsdam, Germany:

"Global warming has an effect on tropical storms and their impact. One aspect is that although not the only factor, warmer ocean temperatures tend to increase storm intensity, and many of the strongest storms on record world-wide have indeed occurred in recent years. The Atlantic in the path of Florence is unusually warm at present. Another aspect is that sea-levels are rising in response to global warming - in North Carolina by about a foot (30 cm). That makes the coast more vulnerable to storm surges."

Also on this issue,
Dim Coumou, research group leader at the Potsdam Institute for Climate Impact Research and scientist at Vrije Universiteit Amsterdam, Netherlands:

"Due to global warming, the warmer air in a Hurricane can hold more water vapor causing more intense rainfall. In addition, the atmospheric circulation in the Northern Hemisphere during the warm season has been weakening. This is seen both in the tropics and mid-latitudes and that increases the chance of stalling hurricanes. We have seen this last year with storm Harvey, at that time leading to human tragedy, and unfortunately we now see it again - we can only hope the impact will be less severe."

On the issue of hurricane damages, Tobias Geiger from the Potsdam Institute for Climate Impact Research (Research Domain Climate Impacts and Vulnerabilities):

"The majority of damages from hurricanes is caused by storm surges and precipitation. While Florence's strength in terms of windspeed decreased prior to landfall - it was not a major hurricane landfall as anticipated earlier - her size has increased tremendously. Therefore even larger portions of the coast are affected by surge and extreme rainfall and damages might unfortunately rise accordingly. Last year tropical cyclones caused more than US$ 280 billion in damages globally. Under global warming, we might observe an increasing number of very intense tropical cyclones - paired with more expensive assets in highly vulnerable locations, tropical cyclone damages are expected to rise in the future."