Something that was fun for me to learn when I worked more directly in climate science and related analysis is how fraught it is that scientists use "average temperatures" in public communications of climate research. I personally was first exposed to this during my work on the Risky Business Project in 2013 - 2014, which quantified the economic risks of climate change in the United States.
My colleagues (namely, Kate Gordon and Trevor Hauser) had two keen insights: First, that traditional cost-benefit analyses were hiding the tail risk of unmitigated climate change — because the discount rates that economists used in their climate models were insanely high. If there’s a 5% risk that a climate-infused hurricane permanently knocks out 100% of the economy in, say, a coastal Florida city that then ceases to exist, what is the appropriate discount rate?
Classical cost-benefit economics said it should be close to 100%, since the economy would run at 100% right up until it ceased to exist — but then, would ignore the part about it no longer existing. “Oh,” they said, “We can just rebuild the city [editor’s note: the “city” is now coral reef habitat] and then the economy will go back to 100%.”
As we say in California, yeah, no.
A risk assessment would do away with discount rates in favor of … a risk assessment: A 5% risk of a 100% loss is the sort of thing that actuaries and insurers deal with all the time; they’re required (by law and good fiduciary judgment) to assess risk based on the real economic costs/value of replacement. If risks get too high — say, expected losses exceed available capital reserves or your ability to replenish them —then, those losses are uninsurable (coming soon to a high-flood or high-fire-risk property near you).
The second keen insight was that the use of averages by climate scientists in describing climate-related temperature increases and related impacts — we’ve all heard of “1.5 degrees” and “2 degrees C” — was unintentionally serving to hide the entirety of the risk of climate impacts. That’s because humans don’t live on this planet on average; we live on earth in specific locations. And the impacts of climate change in all of the specific locations on earth are wildly heterogenous, uneven, and discontinuous.
So an “actionable” climate risk assessment would break down the average findings of climate science, to the degree possible — climate models are continuously improving their resolution, and they’ve gotten pretty good. Such a breakdown would start to yield insights into how bad it might get, exactly, where you actually live, as opposed to where the “average human” (who does not exist) lives.
These findings bear exceptionally bad news, for the simple reason that an average of all global temperatures will have a ton of very high numbers, averaged with a ton of not so high numbers, and a whole bunch of numbers in the middle.
Put even more simply: Global average temperature increases of 3.6 degrees F (2 degrees C) could mean some places get 30 degrees F warmer, and some places getting 0.1 degree warmer. And in fact, we’re already seeing an early version of this play out in the Arctic, where temperatures are up 400% more than “global averages.”
To wit: Climate change is gong to be substantially worse in some places than in others.
By the end of this century, projections under a high-emissions scenario, temperatures in California would rise by an average of almost 9 degrees Fahrenheit. Inland areas are projected to have greater increases than areas along the coast, with temperature jumps varying from 6 to 11 degrees in different parts of the state.
Let’s unpack that 9 degree figure. It’s an average for the whole state. One thing I can tell you for certain is that cities like San Francisco are pulling that average down: When it’s 125 degrees in Death Valley in August, it’s usually in the 50’s in foggy SF. If those were the only two places in California, the state’s “average temperature” would be an endless summer of 87 degrees F.
But again, nobody lives in “average California.” And because of our NIMBY housing policies in cool, coastal cities like San Francisco, we’re essentially condemning entire generations of Californians to the extreme end of the distribution curve — places where temperatures will go up by much more than 10 degrees F, while we’re chilling with Karl in Golden Gate Park. Their lives will be lived on the edge, at best.
“Those that will be impacted most include those least able to adapt,” Callahan of UCLA’s Luskin Center said.
The San Francisco Chronicle has been stepping up its game on the coverage of this issue (this story inspired me to write this retrospective-ish piece), and this is another phenomenal installment in their growing ouvre on climate, housing, and related topics. I’m a proud paid subscriber and encourage everyone who can to pay for local and regional news. It’s the true backbone of democracy.