Global warming must stay below this level for west Antarctica's ice sheet

Rising seas are already making storm damage more costly, adding to the impact on about 700 million people who live in low-lying coastal areas at risk of flooding.

Scientists expect sea-level rise will exacerbate the damage from storm surges and coastal floods during the coming decades. But predicting just how much and how fast the seas will rise this century is difficult, mainly because of uncertainties about how Antarctica’s ice sheet will behave.

The recent Intergovernmental Panel on Climate Change (IPCC) projections of Antarctica’s contribution to sea-level