Humans have always been at the mercy of extreme weather events, such as storms, heatwaves, and floods. However, there is no doubt that the climate crisis, a phenomenon driven by human activity, is amplifying many of these natural disasters and adding to their social, economic, and environmental costs.
Now, a team of researchers has estimated just how much human-related climate changes can cost societies by spotlighting Hurricane Sandy, a 2012 storm that devastated communities along the Atlantic coastline, as a model.
Led by Benjamin Strauss, president and chief scientist of the nonprofit Climate Central, the scientists calculated that $8.1 billion of the $62.7 billion in damages incurred by Sandy in the US northeast “are attributable to climate-mediated anthropogenic sea level rise,” according to a study published on Tuesday in Nature Communications. The team also found that Sandy affected about 71,000 more people when compared to models in which humans were not contributing to rising sea levels.
“Lots of great research has identified climate fingerprints on many different big storms, heat waves, and more, but we couldn't find any research showing how climate had worsened damages from any single event,” Strauss said in an email. “We realized that the effect of sea level rise would be easy to isolate and make an intuitive and rock-solid case.”
Strauss and his colleagues focused on sea level rise because this metric clearly worsened Sandy’s horrifying impact, which included hundreds of fatalities. While sea levels naturally shift over geological epochs, humans have been substantially contributing to coastal erosion and expanding oceans since the dawn of the industrial era, due to anthropogenic emissions of greenhouse gases.
Strauss and his colleagues used historical data to calculate that anthropogenic activity has raised sea levels around the New York tri-state area by about four inches since 1900. While that measurement may not sound like much in our day-to-day lives, it can allow storm surges from hurricanes to rush further inland into heavily populated regions, like the Eastern seaboard.
The team generated a range of dollar estimates tied to anthropogenic sea level rise as a portion of Sandy’s total economic cost; $8.1 billion represents the median number. The figure represents about 13 percent of Sandy’s total cost to the tri-state region, a significant fraction that does not even account for other possible human-linked climate effects like thermodynamic change, which can make storms more intense.
“I think most people don't come close to realizing how much climate change is already harming us,” Strauss said. “If as a scientist, I can make that picture a bit clearer, my hope is that that will lead governments and businesses to take actions that better reflect and address the growing threat we face.”
As global temperatures and sea levels continue to rise as a result of anthropogenic activity, the percentage of storm damages that can be directly linked to human-related climate effects will also increase. Isolating this factor can help scientists understand the role our species has played in exacerbating extreme weather events that we have already endured, while also anticipating the self-inflicted damages from disasters we may face in the coming decades.
“We hope that other research teams will take up and improve our methods and apply them to many other storms,” Strauss concluded. “We have plans to do the same thing. In principle, just about every damaging coastal flood of the last half century, anywhere, was made worse by human-caused sea level rise. The total cost could really add up.”