Sea level rise isn’t a problem that can be offshored. Even for the world’s largest economies and wealthiest nations, the cost of decarbonizing plus preparing for sea level rise that’s already inevitable will produce less economic harm in the long run than doing nothing.
To demonstrate this, an international team of researchers used a combination of climate, coastal flooding, and economic models to calculate the effects of rising waters on gross domestic product (GDP). They considered four different scenarios based on whether global carbon emissions are reduced to levels compatible with the Paris Agreement’s goal of holding warming well below 2° C or overshoot that benchmark, and whether countries undertake measures to adapt to higher waters or not.
Failure both to curtail carbon emissions and to implement adaptation measures could cost the global economy 4% of GDP annually by 2100, the researchers reported last week in Environmental Research Communications.
Both decarbonization and adaptation will require substantial financial outlays. But in combination, these efforts could hold global GDP losses to less than 0.5% annually at century’s end.
“This confirms the importance and economic efficiency of adaptation in the long term: Making sure that coastal communities and their infrastructure are climate-resilient will affect economies across the globe much less than persistent climate impacts in the absence of climate action,” Thomas Schinko, lead author of the study and a scientist at the International Institute for Applied Systems Analysis, said in a statement.
Unlike previous studies, which have calculated the direct economic effects of coastal flooding, the new work models how those costs reverberate through the economy as a whole. The researchers have projected costs not just at a global level but also for the EU and individual members of the G20, a group of the world’s 20 largest economies. They also break down the effects on different sectors of the economy.
The largest impacts are predicted for China, which is set to lose 9-10% of GDP if carbon emissions are curtailed but no further adaptation measures are put in place, and 11-12% if emissions also exceed the Paris Agreement benchmark.
Without adaptation, Europe and Japan will also see severe economic impacts from sea level rise by 2100. The world’s largest emitters also tend to be the places where sea level rise will have the largest economic impacts as a percentage of GDP.
But individual G20 countries could all limit economic impacts below 1% of GDP if they make both decarbonization and sea level rise adaptation a priority, the researchers found.
The most vulnerable economic sectors in no-adaptation scenarios are construction, agriculture, and energy intensive industries. But construction is one of the least impacted sectors if strong adaptation measures are put in place – largely because adaptation involves building infrastructure, they note.
Source: Schinko T. et al. “Economy-wide effects of coastal flooding due to sea level rise: a multi-model simultaneous treatment of mitigation, adaptation, and residual impacts.” Environmental Research Communications 2020.