Bill Gates is right to recalibrate on climate change

Decision making under deep uncertainty is a nightmare. What if it was a lucid dream?

Climate change breaks our brains. It always has. It’s a problem that concerns everyone, of severity we can only guess at, on time-scales we can’t make out.

It may turn out to be a civilization-blighting calamity, or it may turn out to be a civilizational bump in the road. We don’t know how much warming corresponds with how much extra CO₂ in the atmosphere, we don’t know how much damage corresponds with how much warming, and we don’t know how quickly or slowly these impacts will hit.

All the modelers can do is propose probability distributions of future calamities for us to ponder.

We’re bad at thinking in these terms — of course we are. We have puny little caveman brains designed to keep us alive on the edge of an African savannah, we’re nowhere near equipped to deal with a threat like this.

I’ve always been fascinated by this ineffable quality of climate change, what researchers sometimes call “deep uncertainty.”

It’s not just that we can’t quite agree on what’s likely to happen. It’s that we can’t agree on how much the things we do to mitigate those impacts are likely to matter. We don’t even agree on how we could come to agree on those things. Climate change is like that — a sui generis problem that we dread in proportion to how much we’re baffled by it.

One response to deep uncertainty is catastrophism: the very human instinct to say “look, we can’t really measure this risk, so we’re probably best off planning on the basis of the worst case scenario.” This is the path that most of the climate universe has taken over the last ten years, and even now I’m not comfortable dismissing it.

Some very eminent climate scientists think the consensus is wrong, and the most likely outcome is worse than the IPCC consensus suggests. Nobody who understands deep uncertainty can dismiss their alarm. Given an unquantifiable possibility of ending up in a very unlivable world, doesn’t prudence demand that you act on that basis?

This is the intuition behind catastrophism: the confident assertion that we’re definitely heading for a worst case scenario. This is the mindscape behind “Don’t Look Up”, the classic Greta Thunberg stance, the default position of the 21st century climate movement. For too long, we’ve been too shy to point out the logical fallacy at its core — the possibility of a catastrophic outcome is not the same as certainty of that outcome. Just the opposite: worst case scenarios are tail risks. By definition, they’re not the most likely outcomes.

On balance of probability, we’re on a still-bad-but-probably-survivable trajectory. A three-degrees-hotter world is one with weather that’s much more hostile, one where some places do need to be evacuated but also one where, for most of the people most of the time, civilization keeps chugging along.

Which is why, all in all, I think Bill Gates’s recent letter urging a rethink in our approach to climate change is a good one. Not because we’re definitely going to avoid the worst outcomes —“definitely” is not a word that belongs in any intelligent person’s assessment of climate risks— but because the range of possible outcomes includes many that are less catastrophic than the one we’ve been told is inevitable. And because regardless of where we end up, we’re better off facing what’s coming if we’re richer than if we’re poorer.

Gates deserves kudos for putting his head above the parapet and saying sane thing many people don’t want to hear. It takes actual courage to speak up in the way he has, and we should always applaud actual courage.

There are zero guarantees in climate, that much we know. It’s possible that, come 2050 or 2075, we’ll be on a much more destructive weather trajectory than seems likely right now, and then people will look back on Gates’s letter and say what a dunce he was. Or it may be that 2075 comes around and we’re towards the not-so-bad end of the probability space, and then people will look back and hail Gates as a visionary. We can’t know. He can’t know.

What we can know is that whomever ends up being on the receiving end of the worst climate impacts is going to be much better off if they’re relatively richer than if they’re poorer. And on that score, Bill Gates is unquestionably right.

We live in polarized times, so Gates’s sensible course correction will be perceived as caving to the denialists. That can’t be helped. I care a lot less about that than I care about the substance. Decision making under deep uncertainty is a nightmare. Bill Gates wants to turn that nightmare into a lucid dream. We should take him up on that.