For the past 30 years, the global approach to climate policy has been making grand promises and later mostly failing to live up to them. At his World Leaders Climate Summit, President Biden promised to cut about twice as much carbon as what Obama promised, which was hailed as decisive and bold climate action. This is equivalent to decreasing an additional 1.5 billion tonnes of greenhouse gas annually by 2030 beyond Obama’s commitments. But what would this achieve? Let us assume that Biden and future presidents manage to get emissions cut as promised by 2030. And let us assume miraculously that the many future presidents from 2030 to 2100 manage to continue that feat. If we use the standard UN climate model, it turns out that Biden’s new promises will reduce warming by the end of the century by a rather small 0.07°F. Biden told us that his climate policy would make Americans more prosperous. That is implausible. If climate policies really were making us richer, everyone would scramble to shed fossil fuels and pile on the renewables. Instead, his own summit showed the need for arm-twisting even just to make a few of the participants promise expensive new policies.