If the 2°C warming limit set by the Paris Agreement is exceeded, flooding from rising sea levels could cost the global economy $14 trillion every year by 2100, a new study warns.
The work was published by the UK National Oceanographic Centre in the journal Environmental Research Letters on Wednesday. Researchers assessed sea level rise projections under three different scenarios: one in which warming is limited to 1.5°C, a second in which it is limited to 2°C and a third in which warming is unrestricted.
The team found that warming of 1.5°C would lead to a 0.52-meter increase in sea level, warming of 2°C would cause a 0.86-meter increase in sea level and unrestricted warming would result in a 1.8-meter rise in sea level, reports Newsweek. By combining this information with individual country data from the World Bank and the Dynamic Interactive Vulnerability Assessment modelling framework, the team examined the impacts these different scenarios would have on individual countries and at the global level.
According to the results, upper-middle income countries would be hit the hardest by flooding costs. China is expected to be particularly affected due to its large coastal population, long coastline and rising GDP. As a percentage of GDP, flooding costs are projected to be highest for Kuwait (24%), Bahrain (11%), the United Arab Emirates (9%) and Vietnam (7%).
Although high-income countries will not be spared by flooding, they tend to have more protective infrastructure already in place, and therefore could avoid some of the associated costs.
“More than 600 million people live in low-elevation coastal areas, less than 10 meters above sea level,” lead author Dr Svetlana Jevrejeva said in a statement. “In a warming climate, global sea level will rise due to melting of land-based glaciers and ice sheets, and from the thermal expansion of ocean waters. So, sea level rise is one of the most damaging aspects of our warming climate,” she explained.
Even if warming is limited to 1.5°C, researchers found that flooding costs would reach as much as $10.2 trillion per year by 2100, while unrestricted warming would have catastrophic consequences for the global economy. With 1.8 meters of sea level rise, flooding costs are projected to reach $27 trillion per year, which equates to 2.8% of global GDP.
“These extreme sea levels will have a negative effect on the economies of developing coastal nations, and the habitability of low-lying coastlines,” said Dr Jevrejeva. “Small, low-lying island nations such as the Maldives will be very easily affected, and the pressures on their natural resources and environment will become even greater,” she added.
Researchers emphasised that costs could be kept in check if efforts to limit global warming and subsequent sea level rise are ramped up. The authors concluded that failing to keep warming below 2°C would have large socio-economic costs and said effective adaptation measures could save the world a significant sum. Flooding costs in the same 1.5 °C scenario in 2100 could be limited to $1.1 trillion per year if immediate action is taken to reduce emissions and improve flooding preparedness.
The team said their findings underscore the importance of reducing emissions and investing in the development of strategies and infrastructure to deal with increased coastal flooding.
“These results place further emphasis on putting even greater efforts into mitigating rising global temperatures,” said Dr Jevrejeva.