An update on the thermosteric sea level rise commitment to global warming

Magnus Hieronymus

doi:10.1088/1748-9326/ab1c31

Abstract

The equilibrium thermosteric sea level rise caused by global warming is evaluated in several coupled climate models. The thermosteric sea level rise is found to be well approximated as a linear function of the mean ocean temperature increase in the models. However, the mean ocean temperature increase as a function of the mean surface temperature increase differs between the models. Our models can be divided into two branches; models with an Atlantic meridional overturning circulation that increases with warming have large mean ocean temperature increases and vice versa. These two different branches give estimates of the equilibrium thermosteric sea level rise per degree of surface warming that are respectively 98% and 21% larger than the estimate given in the IPCC Fifth Assessment Report. Our estimates of the equilibrium thermosteric sea level rise are also used to infer an equilibrium sea level sensitivity, a parameter akin to the often used equilibrium climate sensitivity metric.

Highlights

Sea level rise is a serious consequence of anthropogenic climate change, having the potential to increase the cost of coastal flooding damage by orders of magnitude already toward the end of the century (Vousdoukas et al 2018)
The aim of this paper is to present an updated assessment of the thermosteric sea level rise commitment to global warming, using an analysis of data from more comprehensive climate models that have been run to steady state
New estimates of the equilibrium thermosteric sea level commitment of global warming was derived from an analysis of near steady state integrations of several coupled climate models with different forcing agents causing the global warming

Summary

Introduction

Sea level rise is a serious consequence of anthropogenic climate change, having the potential to increase the cost of coastal flooding damage by orders of magnitude already toward the end of the century (Vousdoukas et al 2018) These immediate concerns as well as the great computational cost of running long integrations with global climate models has lead much of the sea level research to focus on the time period until the end of the century (Church et al 2013). The assessment by Levermann et al (2013) of the equilibrium thermosteric sea level rise was in turn based on integrations of climate models of intermediate complexity that were first presented in AR4 (Solomon et al 2007) These numbers for the thermosteric sea level rise commitment to global warming have not been updated for a long time, and they are based on models that are far more idealized than our current generation of climate models. The aim of this paper is to present an updated assessment of the thermosteric sea level rise commitment to global warming, using an analysis of data from more comprehensive climate models that have been run to steady state

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