Last week, Hurricane Erin was a massive Category 5 storm that shot the gap between the U.S. east coast and Bermuda before heading out to sea. Imagine an alternative universe, where Erin’s track was just a bit further west — tracking over Miami, along the U.S. east coast, and then making a direct hit on New York City.
Here is how the imaginary newspaper article at the top of this post might have begun:
After making direct hits on both Miami and New York City, Hurricane Erin will certainly be the most destructive storm to strike the United States, with early damage estimates totaling over $1 trillion — making it the world’s first trillion-dollar disaster. Tragically, Erin has also caused more than 300 deaths, the deadliest U.S. hurricane since Katrina in 2005. According to scientists at the non-profit ClimateAttribution4U, the storm was made 72.6% more likely due to climate change . . .
Back here in the real world, The Washington Post recognized Erin’s near miss:
[I]nstead of taking a taking a left hook into the Mid-Atlantic like Sandy [2012] did, Erin turned right and swirled out into the open ocean. But it was a closer call than most people probably realize. . . “The United States is really fortunate Erin stayed offshore since its exceptional size and unusually low pressure would have translated to more destructive power had it come ashore,” said [hurricane expert Michael] Lowry.
“Extreme event attribution” — discussed in depth in a THB series call Weather Attribution Alchemy (links at bottom) — focuses on making the case for why the-extreme-event-that-just-happened was worsened or made more likely due to climate change.1
But what about the-extreme-event-that-didn’t-just-happen?
I asked Grok to perform an “extreme non-event attribution” analysis of Hurricane Erin’s track that kept the most intense effects of the storm well offshore:
You’ve likely heard claims that climate change is making the jet stream more “wavy.” Although research does not generally support this hypothesis, let’s go with it for purposes of discussion.
If indeed climate change is altering the jet stream, then as a matter of simple logic that wavier jet stream is necessarily influencing the paths of hurricanes, including — in some cases — keeping powerful storms from striking the U.S. east coast, as we saw last week.
There is in fact peer-reviewed research suggesting that changes in steering currents resulting from human influences on climate may increasingly keep intense hurricanes offshore — Barnes et al. 2013 concluded:
Using the Coupled Model Intercomparison Project, phase 5 multimodel ensemble, we demonstrate that climate models consistently project a decrease in the frequency and persistence of the westward flow that led to Sandy’s unprecedented track, implying that future atmospheric conditions are less likely than at present to propel storms westward into the coast.
[F]uture projections of hurricane activity (1980–2100), downscaled from multiple climate models using a synthetic hurricane model, show an enhanced hurricane frequency for the Gulf and lower East coast regions. The increase in coastal hurricane frequency is driven primarily by changes in steering flow, which can be attributed to the development of an upper-level cyclonic circulation over the western Atlantic.2
One recent study of modeled hurricane damage look at the magnitude of damage that could have happened if several recent storms took a counterfactual track. They concluded that losses from a single storm could indeed exceed $1 trillion. It is not far fetched that Erin’s near miss saved us from a trillion-dollar disaster.
A trillion dollars here and a trillion dollars there, and the benefits of changes in climate due to human influences resulting from disasters prevented really start to add up!
Of course, all of this is more than a little tongue-in-cheek. “Extreme non-event attribution” is every bit as dodgy as “extreme event attribution.” The gold standard for detecting changes in weather phenomena and attributing changes to particular causes remains the IPCC’s detection and attribution framework.
