Hartford Courant (Sunday)

Climate change getting worse, and it’s harder to predict

- By Gary Yohe

Extreme weather events are now among the most destructiv­e ever experience­d. Climate and weather disasters in the United States since 2010 have averaged $80.2 billion in economic damage with 521 lives lost per year. But the reality is, that number is going up. Between 2015 and 2019, annual damages averaged $106.3 billion with 772 lives lost.

None of this is news to people who have been impacted by extreme weather and to scientists like me who have been paying close attention to these troubling trends. For decades, variable climate trajectori­es have wobbled along their trendlines as atmospheri­c concentrat­ions of carbon dioxide resulting from human activity have increased since 1955 to produce seven of the hottest ten years in history since 2010.

We’re starting to see these impacts manifest themselves in the weather we’re seeing, and the science is now telling us that something new and even more threatenin­g is afoot. It is called “regressing toward the tails” — a very technical but very important new developmen­t.

What is it? It is the increasing tendency that extreme events caused by climate change never seem to be as bad as they could have been. While that doesn’t sound like cause for alarm, what it really means is that it is ever more likely that the next extreme weather event — be it fire, flood, drought or heat wave — will be even worse than anything that we have previously experience­d. So as a result of climate change, the most damaging impacts we’ve

seen so far is becoming the new normal while mother nature keeps upping the ante.

Take a look at the worst wildfire year in California’s history: 2017. As of December 22, 2017, 9,270 fires had burned 1,548,429 acres, but this year has topped that. As of Oct. 2, more than 7,900 fires had already burned 3.6 million acres with two months left in the fire season. In fact, the largest wildfire in California history has been joined since August by the third, fourth, fifth and sixth largest of all time, and they are still burning.

During the last few weeks, the California wildfires have most frequently been caused by thousands of dry lightning strikes born of monsoon winds from Tropical Storm Fausto off the coast of Mexico. The strikes repeatedly hit drought-ravaged and tinder

dry forests during a near record heat wave. The northern part of the state is experienci­ng the perfect storm of these five conditions that all lie on the extreme tips of their independen­t frequency distributi­ons.

Things are not just getting worse. They are also getting harder to control, prevent and predict. Human behavior used to be the usual cause California fires, meaning future threats could be mitigated by taking strong proactive action against future events. But this year, residents can only retreat from the harm as quickly as possible and hope that the climate will change back. But he climate will not change back, and where can they go? As we continue to see, the COVID-19 pandemic is confoundin­g evacuation efforts.

The science community has been studying these weather events closely and has developed a growing understand­ing of what is really going on, but we are now challenged to communicat­e that knowledge clearly to the general public and lawmakers.

There are at least four problems in this regard. First, people often mistake weather for climate. Second, they really don’t care whether next year will be a warmer or cooler than this year. Third, they find it difficult to internaliz­e signal from noise along long-term trends. And fourth, they are very familiar with pendulums.

What’s the problem with pendulums? They give people a false sense of predictabi­lity and a misguided sense of stability. People are used to being mesmerized by stationary ones, but the climate is dynamic. The climate pendulums are no longer returning to equilibriu­m at their lowest points in their arcs. Why? Because their pivot points are moving and accelerati­ng in a dangerous direction (the long term trends) so that the swinging weights of the pendulums are blowing by their historical limits into some very dark extremes.

Gary Yohe is the Huffington

Foundation Professor of Economics and Environmen­tal Studies, Emeritus, at Wesleyan University in Connecticu­t. He served as convening lead author for multiple chapters and the Synthesis Report for the Intergover­nmental Panel on Climate Change from 1990 through 2014 and was vice chair of the Third U.S. National Climate Assessment from 2012 through 2015.

 ?? THE NEW YORK TIMES ?? Smoke rises above Paradise, California, on Nov. 9, 2018.
THE NEW YORK TIMES Smoke rises above Paradise, California, on Nov. 9, 2018.

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