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Sea-level rise can be slowed by achieving the Paris Agreement, new research shows



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Achieving the aim of the Paris Agreement, (to hold the rise in global average temperatures to well below 2 °C and to pursue efforts to limit the temperature increase to 1.5 °C), by the end of this century could dramatically reduce potential sea-level rise compared to projections based upon business-as-usual scenarios.

“A lot of research on sea-level change had previously focused upon high future Global Warming” says Luke Jackson from the Institute for New Economic Thinking at the Oxford Martin School and lead author of the research article published this week. “Since the Paris Agreement was signed in late 2015, there has been a switch in focus to think carefully about how the climate (including sea level change) will respond if we succeed in achieving Paris’s aims.”

Future sea-level rise has the potential to affect millions of people and billions of dollars’ worth of infrastructure world-wide by increasing the vulnerability of coastlines to flooding from tides, wind-driven waves and storm surges.

In the study, “21st century sea-level rise in line with the Paris accord” published this month in Earth’s Future, the authors, Luke Jackson, Aslak Grinsted and Svetlana Jevrejeva, apply a novel method to project future sea-level rise at a global and a regional level for the two temperature levels stated in the Paris Agreement.

The new research shows that achieving a 1.5 °C or 2 °C temperature rise by 2100 could result in a global sea-level rise of 44 cm and 50 cm respectively. This is in contrast to a rise of 84 cm for a business-as-usual scenario (as we reported here) if temperature rises around 4 °C by 2100. The difference between achieving Paris and a business-as-usual scenario is even more marked when comparing low-chance (1-in-20), high impact projections. In this case, the global projections are 67 cm versus 180 cm for 1.5 °C and business-as-usual respectively, a difference of more than 1 metre.

Differences of this size are significant for decision makers regarding Climate Change mitigation (achieving the Paris Agreement will require rapid, deep emissions reductions ) and coastal adaptation strategies. The Intergovernmental Panel on Climate Change will publish a Special Report on Global Warming of 1.5 °C later this year – among whose lead authors include Oxford Martin Fellow, Myles Allen.

 

Jackson, L. P., Grinsted, A. and Jevrejeva, S. (2018), 21st century sea-level rise in line with the Paris accord. Earth's Future. doi:10.1002/2017EF000688