Cutting-edge research called “attribution science” makes climate risks real for companies

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Source: Nature

We’ve seen the wave of destruction that extreme weather events have left around the world over the summer, from hurricanes to heat waves. A common question that arises after these events is: Are they climate change?

It’s a complex question, with an even more complex answer that has implications on several industries. There has always been extreme weather, but climate change can increase extreme weather’s frequency and severity on average. Now, a relatively new field of research called “attribution science” is looking to measure how atmospheric factors affect individual extreme weather events.

Attribution scientists compare observations of the weather events on our planet under its current warming climate conditions to how events would hypothetically occur on a hypothetical “Planet B” that has a climate untouched by greenhouse gas emissions. Scientists use sophisticated physics-based simulations of the atmosphere, ocean, and land surface, all run on supercomputers. They can identify how strong, how long, how big and how likely the event would be in that imaginary world, then see how it stacks up to the real-world event. It converts climate change trends into more tangible and specific facts, and it’s been gaining significance in the past decade.

“The underlying concept used in this first study and subsequent ones is similar to the way we understand risk in public health: Just as medical researchers can study how smoking cigarettes changes people’s risk of lung cancer by comparing data from smokers and nonsmokers,” according to Slate.

Model simulations that included only natural influences on climate (pink line) diverge sharply from observed surface temperatures (charcoal line) around 1970. By 2015 (gray dot), only the model average that included rising carbon dioxide levels (red line) resembled the real world. Source: NOAA Climate.

Scientists have found that within the past few years, there have been events — like a 2017 marine heat wave off the coast of Australia or Japan’s deadly 2018 heat wave — that would not have happened without climate change.

Researchers can now also put a number on how much the odds of an extreme event have changed over time. News stories discussing how, say, a once-in-100-years event is now happening once every 10 years, that tenfold risk increase can be attributed to climate change.

In particular, climate change made a storm with as much rainfall as 2017’s Hurricane Harvey three times as likely. Scientists also calculated that three-quarters of the tens of billions of dollars in Harvey’s economic damage stemmed from this additional rainfall attributed to climate change.

Attribution science has wider implications across the business and regulatory landscape. It’s increasingly being used in climate change litigation — lawyers representing citizens, cities, and states have cited attribution science numbers to file lawsuits over damage allegedly caused by climate change. The UN reported in 2020 that a rapid increase in climate litigation has occurred around the world: “In 2017, there were 884 cases brought in 24 countries. As of July 1, 2020, the number of cases has nearly doubled with at least 1,550 climate change cases filed in 38 countries.”

In the U.S., city governments from New York City to Los Angeles have moved to sue oil supermajors like BP and Exxon Mobil for climate damages from extreme weather events like Hurricane Sandy and wildfires.

Source: Herbert Smith Freehills

It may be years until these cases are settled. But they could set a precedent and raise the level of risk for carbon-intensive businesses if they don’t mitigate emissions.

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