Politicians, economists and even some natural scientists have tended to assume that tipping points¹
in the Earth system — such as the loss of the Amazon rainforest or the
West Antarctic ice sheet — are of low probability and little understood.
Yet evidence is mounting that these events could be more likely than
was thought, have high impacts and are interconnected across different
biophysical systems, potentially committing the world to long-term
irreversible changes.

Here we summarize evidence on the threat of
exceeding tipping points, identify knowledge gaps and suggest how these
should be plugged. We explore the effects of such large-scale changes,
how quickly they might unfold and whether we still have any control over
them.