Multi-century global and regional sea-level rise commitments from cumulative greenhouse gas emissions in the coming decades

Sea levels respond to climate change on timescales from decades to millennia. To isolate the sea-level contribution of historical and near-term GHG emissions, we use a dedicated scenario and modelling framework to quantify global and regional sea-level rise commitments of twenty-first century cumulative emissions. Under current climate policies, emissions until 2050 lock in 0.3 m (likely range 0.2–0.5 m) more global mean sea-level rise by 2300 than historical emissions until 2020. This additional commitment would grow to 0.8 m (0.5–1.4 m) for emissions until 2090, of which 0.6 m (0.4–1.1 m) could be avoided under very stringent mitigation. Resulting regional commitments would be around 10% higher than the global signal for the vulnerable Pacific region, mainly due to higher relative Antarctic contributions. Our work shows that multi-century sea-level rise commitments are strongly controlled by mitigation decisions in coming decades. It is important to understand how much long-term sea-level rise is already committed due to historical and near-term emissions. Here the authors use a modelling framework to show how decisions on global emissions reductions in the coming decades alter multi-century sea-level rise projections.