Uncertainty principles

摘要

Last weekend, delegates from 195 nations agreed an ambitious deal to tackle climate change. As our correspondent reported from the euphoric final session, there was "no pause, no hesitation, no time to even breathe" - or register a last-minute objection - before the gavel was banged down. As a declaration of intent, the agreement is impressive. But it is far too late: it would have been truly bold and timely 20 years ago. As a call to action, it is quixotic: its aspiration of a 1.5 ℃ cap on global warming seems almost totally unachievable (see page 8). Nonetheless, the deal is to be welcomed. It marks the world's acceptance that climate change, driven by humans' greenhouse gas emissions, is about as close to a certainty as science can ever get - and that conclusion cannot be covered up or waved away.