29 October, 2019

Attributing long-term sea-level rise to Paris Agreement emission pledges


Alexander Nauels, Johannes Gütschow, Matthias Mengel, Malte Meinshausen, Peter U. Clark, Carl-Friedrich Schleussner

The multicentennial sea-level rise commitment of pledged near-term emission reduction efforts under the Paris Agreement has not been quantified yet. This report estimates this sea-level rise commitment and find that pledged emissions until 2030 lock in 1m of sea-level rise in the year 2300.

The main contributors to sea-level rise (oceans, glaciers, and ice sheets)respond to climate change on timescales ranging from decades to millennia.

A focus on the 21st century thus fails to provide a complete picture of the consequences of anthropogenic greenhouse gas emissions on future sea-level rise and its long-term impacts.

Here we identify the committed global mean sea-level rise until 2300 from historical emissions since 1750 and the currently pledged NationalDetermined Contributions (NDC) under the Paris Agreement until2030.

Our results indicate that greenhouse gas emissions over this 280-y period result in about 1 m of committed global mean sea-level rise by 2300, with the NDC emissions from 2016 to 2030 corresponding to around 20 cm or 1/5 of that commitment.

We also find that 26 cm(12 cm) of the projected sea-level-rise commitment in 2300 can be attributed to emissions from the top 5 emitting countries (China, United States of America, European Union, India, and Russia) over the1991–2030 (2016–2030) period.

Our findings demonstrate that global and individual country emissions over the first decades of the 21st century alone will cause substantial long-term sea-level rise.