John Diaz: Unchecked climate change may lead to more “extreme weather events.”
Amid the heartbreaking death and devastation inflicted by Hurricane Harvey were inspirational stories of the heroic efforts of people who put their own safety at risk to help others. But there also was a maddening element to the scenes out of Texas and Louisiana: This was a glimpse into a future that scientists have been warning about if climate change remains unchecked.
Under the Trump administration, the United States has been retreating when it should be leaning in to curb a human-aggravated phenomenon that is leading to a proliferation of what myriad scientific studies refer to as “extreme weather events.”
Houston is what an extreme weather event looks like. Harvey produced what is officially categorized as a 1,000-year flood, meaning that the chances are 1 in 1,000 of such a disaster occurring in any given year. Houston had a 500-year flood in each of the previous two years.
Was this a crazy statistical anomaly or the result of a changing climate?
Climatologists are always careful to note that it would be foolhardy to blame any individual weather disaster on climate change — just as it is silly to cite a particular cold spell to debunk concerns, as Donald Trump did in mocking global warming and declaring that “our planet is freezing” in January 2014.
In the case of Harvey, the destruction in the Houston area was no doubt magnified by urbanization that reduced the permeability of the land.
Still, the long-term warming pattern, and the significant contributions of carbon emissions to it, is undeniable to nearly all scientists who are not in league with the fossil-fuels industry. Average surface temperatures in 2016 were the warmest since record keeping began in 1880, surpassing the previous records set in 2015 and 2014.
Paul Ullrich, professor of regional and global climate modeling at UC Davis, said the “clear and upward trend” of global temperatures “can’t be attributed to anything other” than greenhouse gases resulting from human activity.
John Nielsen-Gammon, the
Texas state climatologist and professor of atmospheric sciences at Texas A&M, said it would be premature to try to calculate how much climate change intensified Harvey. Scientists will surely be “taking a closer look” at the impact, he noted in an email. But the suspicions are there. “Harvey wasn’t typical, but the same factors that lead to the observed increase in extreme rainfall would have been at work in Harvey too,” he wrote in an essay he forwarded. “Harvey’s air picked up moisture from sea surface temperatures that were running warm, in part because of the long-term climate trend. The atmosphere was supercharged with water vapor compared to what might have happened in a similar storm without warming seas.”
Dan Kammen, a renewable energy expert from UC Berkeley, agreed that a warmed Gulf of Mexico “unambiguously contributed to the massive dump of rainfall on land,” though calculating such influence was “one of the hardest scientific issues.” Ullrich agreed that the volume of precipitation in Harvey “has a climatechange signal in it.”
Its portent for the future is ominous.
“Harvey is entirely consistent and essentially predicted to become part of the new landscape of a climate-changed world,” said Kammen, who recently resigned as a science envoy to the State Department. He left out of disgust with President Trump’s tepid response to the rally of the white supremacists in Charlottesville, Va.
Trump has long been contemptuous of climate-change warnings. He called it a Chinese plot to “make U.S. manufacturing noncompetitive” (2012), “an expensive hoax” (2013) and flat-out proclaimed “I’m not a believer in man-made global warming” (2015).
As president, Trump has moved to reverse the progress President Barack Obama made in elevating this nation to a leadership role on climate. Most notably, Trump announced in June that the U.S. would withdraw from the landmark 2015 Paris climate accord in which 195 nations pledged environmental action.
Scott Pruitt, Trump’s choice to lead the Environmental Protection Agency, arrived as a former Oklahoma attorney general who aggressively filed lawsuits to challenge EPA directives on climate and other issues. Now he is systematically rolling back regulations as he installs a climate-skeptic leadership team.
On Monday, as a wide swath of Texas was submerged in floodwaters, Secretary of State Rex Tillerson notified Congress that a special envoy for climate change would be eliminated as part of a department streamlining.
The U.S. response to a changing climate is going in the wrong direction, even as the dire consequences of inaction become plain.