20 August, 2012

Long-term sea-level rise implied by 1.5 degree and 2 degree Celsius warming levels

A new study led by Michiel Schaeffer of Climate Analytics explores the effect of various potential emission pathways on future sea-level rise, using a model based on data on sea levels over the last millennium.

Some further sea-level rise is already inevitable, with the best possible case being a rise of 59 cm above 2000 levels over the twenty-first century following a hypothetical reduction of emissions to zero by 2016. However, the study underlines the significant impact that different mitigation scenarios will have in determining the extent and rate of sea-level rise by 2100, but even stronger by 2300.

A scenario in which global mean temperature is allowed to increase to 3 degrees Celsius above pre-industrial levels, for example, would involve sea-level rise of between 2 and 4 m over the coming three centuries, while ambitious mitigation targets which limit warming to 1.5 degrees could substantially slow down the rate at which it occurs, resulting in a rise of 1.5 m by 2300, and possibly less than that.

A number of uncertainties are associated with these projections, particularly given the difficulty of predicting the behaviour of the Greenland and Antarctic ice sheets, precise models of which are still being developed. What is clear is that a commitment to multi-meter sea level rise after 2100 can be avoided by immediate action to cut greenhouse-gas emissions.

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