Identifying the causes of sea-level change

Global mean sea-level change has increased from a few centimetres per century over recent millennia to a few tens of centimetres per century in recent decades. This tenfold increase in the rate of rise can be attributed to climate change through the melting of land ice and the thermal expansion of ocean water. As the present warming trend is expected to continue, global mean sea level will continue to rise. Here we review recent insights into past sea-level changes on decadal to millennial timescales and how they may help constrain future changes. We find that most studies constrain global mean sea-level rise to less than one metre over the twenty-first century, but departures from this global mean could reach several decimetres in many areas. We conclude that improving estimates of the spatial variability in future sea-level change is an important research target in coming years. Global mean sea-level change has increased from a few centimetres per century over recent millennia to a few tens of centimetres per century in recent decades. A review of the latest work shows that global mean sea-level rise is unlikely to exceed one metre over the twenty-first century, but regional departures from this global mean could reach several decimetres.