At first sight, it makes a lot of sense to leave other, more complicated or more expensive, interventions for later. But delaying the most difficult actions comes with significant risks. If retrofitting buildings or changing urban travel is difficult and expensive, it is tempting to delay action in these domains until 2030 or 2040. By doing so, however, a country may find itself with a massive stock of inefficient buildings and cities completely dependent on individual cars, with only two or three decades to decarbonize them. With less time in front of us, the task will only seem more daunting by then. Not having acted earlier – and more gradually – in hard-to-decarbonize sectors may well look like a missed opportunity. Long-term strategies – working back from 2050 to determine the decisions and investments that need to be made today – can help countries make these difficult decisions.