Preparing For When Climate Change Throws a One-Two Punch

In May, the Correlated Extremes workshop discussed the odds of extreme events happening together, how those odds are changing as the planet gets hotter, and the potential consequences of these linked events.

Nothing in life is simple, and the same goes for climate change. A city might prepare for the storm surge from hurricanes juiced up by climate change, but what about the heavier rains that come along with them, too? Similarly, as heat waves get worse, how will the added demand for air conditioning impact the electric grid, power sources, and air pollution levels?

Over the last few years, scientists have started to recognize the potential for climate change to cause multiple societal impacts close together in space or time. In light of this emerging threat, Columbia University’s Initiative on Extreme Weather and Climate hosted a three-day workshop at the end of May to focus on planning for when climate extremes get complicated.

The Correlated Extremes workshop discussed the odds of extreme events happening together, how those odds are changing as the planet gets hotter, and the potential consequences of these linked events. Radley Horton, conference organizer and climate scientist at Columbia’s Lamont-Doherty Earth Observatory, said the gathering drew academics as well as policy experts and representatives from government and business.

The workshop examined three types of “correlated extremes” scenarios. The first is when multiple variables interact during a single event — for example, when humidity makes a heatwave more deadly, or when hurricane flooding sparks electrical fires. “If you put all these factors together, the stats look different, and the societal impacts look different,” Horton explained.

The second type of correlated extreme is when events occur in sequence in a given place — like when a hurricane strikes and then knocks out power, or blocks roads and thus hampers rescue and recovery efforts in advance of a heat wave.

Finally, the third type of scenario is when multiple places experience extreme events at the same time. For example, if several of the world’s breadbaskets are struck with drought or destructive rains at the same time, it could wreak havoc on the global food system.

“Just pushing up greenhouse gas concentrations a little more could profoundly increase the probability of some types of correlated extremes,” Horton warned. To him, correlated extremes show that “the climate system and our human and ecological systems may be more vulnerable than we realize, and the societal protection against correlated extremes may not be as large as we realize either.”

Society still has a long way to go in order to prepare for the scaled up disasters that climate change will bring — and particularly those that will occur simultaneously. But Horton sees some evidence that the tide is already turning. He said that heat warning systems in the public health sector are already starting to plan for correlated extremes, and that reinsurance companies are starting to think beyond wind damages from hurricanes to flooding, fire, and lost work hours.

“The main takeaway for me and everyone else was that there’s a big need for this kind of thinking,” said Horton. The workshop identified knowledge gaps and the types of data needed to better understand the impacts of correlated events, and called for better coordination across academic disciplines and between scientists and decision makers. Such partnerships could help climate scientists to hone in on which issues to investigate and how they can provide the most helpful science. These partnerships could also lead to adaptation strategies tailored to correlated extremes, rather than localized individual events. “I think it is important that this topic be in the minds of the growing network of adaptation practitioners,” Horton said.

The workshop organizers are now preparing an article reviewing the definitions, themes, best practices, and research priorities discussed during the event, which they intend to share in a peer-reviewed journal. Video recordings of some of the proceedings are available online.

— Sarah Fecht, Earth Institute

About garen