Homes are surrounded by floodwater after torrential rains pounded Southeast Texas following Hurricane and Tropical Storm Harvey on 31 August 2017 in Sugar Land, Texas. Photo: Scott Olson / Getty Images

By Dana Nuccitelli
5 September 2017
(The Guardian) – Human-caused climate change amplified the damages and suffering associated with Hurricane Harvey in several different ways. First, sea level rise caused by global warming increased the storm surge and therefore the coastal inundation and flooding from the storm. Second, the warmer atmosphere holds more water vapor, which intensifies extreme precipitation events like the record-shattering rainfall associated with Harvey. Third, warmer ocean waters essentially act as hurricane fuel, which may have made Harvey more intense than it would otherwise have been.There are other possible human factors at play about which we have less certainty. For example, it’s possible that Harvey stalled off the coast of Texas because of changes in atmospheric circulation patterns associated with human-caused global warming. As climate scientist Michael Mann notes, his research has shown that these sorts of stationary summer weather patterns tend to happen more often in a hotter world, but we can’t yet say if that happened in Harvey’s case.Other human activities also worsened Harvey’s impacts. For example, Houston suffers from urban sprawl, covering a larger area (nearly 600 square miles) than the cities of Chicago, San Francisco, Washington DC, Boston, Manhattan, and Santa Barbara combined. With urban sprawl and poor planning came expansive impervious surfaces – absorbent soil covered instead by concrete and asphalt, increasing flood risks. Houston’s lack of zoning laws combined with the National Flood Insurance Program (NFIP) also encouraged development in flood prone areas.

We’re subsidizing risky behavior

Private insurance companies don’t want to insure homes that face a significant risk of flooding, but with a lack of regulation and/or government insurance offered by NFIP, development in relatively high-risk flood areas can be profitable. That is, until a flood strikes. 85% of Houston homeowners don’t have flood insurance and will be unable to recover most of their losses from Hurricane Harvey. Others are covered by NFIP, which was already $24 billion in debt before Harvey. That’s because NFIP hasn’t been charging sufficiently high premiums, in large part because it has underestimated flood risks based on maps and projections that are sometimes decades out of date. And climate change is amplifying those flood risks. [more]

Denying Hurricane Harvey’s climate links only worsens future suffering