Do more things at 90% effort. If you believe you can only choose 0% or 100%, you’ll often choose 0% because you cannot afford 100%.

I became very engaged in helping with the climate emergency in the last couple of years. One big line item on the list of emitters is meat. A 100g serving of beef emits the equivalent of 15kg of CO₂ into the atmosphere, the same as driving 78km (48mi). A 100g serving of tofu emits 0.08 kg of CO₂ equivalent.¹ In other words, a week of eating beef emits more CO₂e than three years of eating tofu.²

For someone wanting to reduce emissions, vegetarianism is a clear candidate. But there are some things about being vegetarian I can't do:

1. Summer is deeply carnivorous and I don't want to put her through the effects of my choice (we did try).
2. I don't want to be that person in the friend group people have to plan around, the person whose presence at a barbecue makes an unprepared host feel guilty.
3. There are formats of meat I get occasional cravings for, like a burger or a ball park hot dog.

I can't be 100% vegetarian. But that's no reason to stay at 0%. I can cut meat from the ~90% of meals that don't cause any of these issues.

So I became flexitarian which for me means "vegetarian except when it would inconvenience people". If 90% of the world could become 90% vegetarian the benefit would be nearly that of 100%/100% but orders of magnitude easier to achieve.

We need to adopt this strategy more. It's similar to the 80/20 rule, but 80/20 optimizes bang-for-buck when building things. 90 > 100 is about recognizing that impact per success is a worse thing to optimize for than success rate * impact per success.