Thread by @dwallacewells

Yesterday, I published a long piece on the off-the-charts Pacific Northwest heat dome and what @GovInslee called "the beginning of a permanent emergency." But I left two big and important thoughts out. A thread (1/x). nymag.com/intelligencer/…

The first is well-captured in this bold Guardian front page. The newspaper has repurposed a comment by @Sir_David_King and stood behind it entirely, without quotes or attribution, as, effectively, a statement of fact.

To a certain degree, this probably overstates the near-term lesson of the heat dome, since even under present climate conditions this event appears to be shockingly unlikely. But precisely where it hit really does matter, and it is perhaps all the more terrifying as a result.

It is occasionally said—especially by those hoping to downplay the crisis, but also those endeavoring to be clear-eyed about what the next few decades will bring—that especially in the near-term warming will bring winners and losers. Canada is supposed to be one of the winners.

Looking into the relatively distant future — the second half of the century, say — continued warming makes Canada one of two exceptional countries that could conceivably benefit even under quite grim warming conditions, the other being Russia.

This year, "zombie fires" burned through winter in the Russian arctic, and Canada has experienced what is being conventionally described as a 4.4-sigma heat anomaly—a heat wave so rare, according to the recent record, we would expect it to occur only once every few centuries.

Some have called it a 5-sigma event, which would mean we should expect it once every 5,000 years—once since the time of ancient Egypt.

This heat dome is not the same — not as intense, not as deadly — as heat waves that are hitting the Persian Gulf, Middle East, and South Asia already and with some regularity.

But it is a sign that those in the global North taking a sort of sociopathic comfort in their relative climate luck are deluded to see themselves as safe from the impacts of warming in any absolute way, only relative ones. In British Columbia it was as hot as in Death Valley.

It is also so far from expectations, even expectations that factor in climate changes, that it should force us to wonder a bit about the limits of our current models and how much uncertainty still governs future climate impacts even given a certain level of warming.

Scientists often speak and publish in the language of uncertainty, using distributional ranges to describe impacts. But it can be hard to avoid being mesmerized by median projections and truly appreciate that a 95th percentile outcome still happens 5 percent of the time.

As Martin Weitzman always emphasized, it was in the long tails that the climate risk really resided. That is not just true of climate sensitivity (which could mean emissions we expect would yield 2C could actually yield 3.5C of warming) but for individual impacts as well.

Some of the heat dome is almost certainly just bad luck—when a friend in Seattle asked whether he'd have to just start referring to heat like this as "June" from now on, my instinct was to reassure him that this remained crazily anomalous, even if the trends were all quite bad.

But off-the-charts events also suggest the possibility that the charts aren't calibrated precisely right, either. Which is terrifying, because current projections are scary enough.

Next week is expected another historic heatwave in the American west, this one a bit farther south and probably not as off-the-charts—or not quite. (X/x)

https://twitter.com/WeatherProf/status/1410941566605312007