Our climate is dangerously close to the point of no return — the moment when nothing will ever be the same again. Once certain thresholds, or tipping points, are crossed, chain reactions caused by an accumulation of small changes will shift our climate irrevocably.

But what exactly are these climate tipping points? If they occur over decades or centuries, could we cross them without even noticing? What extreme risks are they already perpetuating and how can we avoid the worst impacts?