Yet as the impact of climate change becomes more evident, so too does the scale of the challenge ahead. Three years after countries vowed in Paris to keep warming “well below” 2°C relative to pre-industrial levels, greenhouse-gas emissions are up again. So are investments in oil and gas. In 2017, for the first time in four years, demand for coal rose. Subsidies for renewables, such as wind and solar power, are dwindling in many places and investment has stalled; climate-friendly nuclear power is expensive and unpopular. It is tempting to think these are temporary setbacks and that mankind, with its instinct for self-preservation, will muddle through to a victory over global warming. In fact, it is losing the war.