Doing Good Better: Effective Altruism and a Radical New Way to Make a Difference

by William MacAskill

However, this standard economic analysis fails to faithfully use expected value reasoning. The standard analysis looks only at the effects from the most likely scenario: a 2–4ºC rise in temperature. It doesn’t consider what the consequences would be if our best-guess estimates are wrong. This is especially important because the climate is an incredibly complex system that is difficult to predict so we can’t be sure that our estimates are correct. When climate scientists make estimates about temperature rise, they have to acknowledge that there is a small but significant risk of a temperature increase that’s much greater than 2–4ºC. The Intergovernmental Panel on Climate Change gives more than 5% probability to temperature rises greater than 6ºC, and even acknowledges a small risk of catastrophic climate change, of 10ºC or more. To be clear, I’m not saying that this is at all likely, in fact, it’s very unlikely.