The priority of Cop27 in Sharm el-Sheikh is to ensure a continuation of life on this planet as we know it. Yet some argue that the goal of limiting the increase in temperatures above pre-industrial levels to the recommended 1.5 degrees should be declared dead: it is no longer realistic. Adapting our goals to our failures is a defeat. If we fail to reduce emissions faster, we will end up having to spend far more on adaptation. We will also have to discover ways of removing vast quantities of carbon from the atmosphere. We may even have to adopt the...