If average global warming exceeds 2.0°C by the end of the century, sea level rise of 1.8 metres (5.9 feet) could result in annual damages worth US$27 trillion, according to a new study led by the UK’s National Oceanography Centre (NOC).
Published in the journal Environmental Research Letters, the study quantified “the pace and consequences of global and regional sea level rise” likely for each of the Paris targets (1.5° and 2.0ºC) and compared those findings with projections for “unmitigated warming,” Climate News Network reports.
“With a temperature rise trajectory of 1.5°C, by 2100 the median sea level will have risen by 0.52 metres (1.7 feet),” said lead author and NOC researcher Svetlana Jevrejeva. “But if the 2.0°C target is missed, we will see a median sea level rise of 0.86 metres (2.8 feet), and a worst-case rise of 1.8 metres (5.9 feet).”
With those numbers as a starting point, the researchers used World Bank data on national incomes to assess “the impact of sea level rise in coastal areas from a global perspective”—critical information, Jevrejeva noted, given that “more than 600 million people live in low-elevation areas, less than 10 metres above sea level.”
The study found that, should global warming be left unchecked, “the global annual flood costs without adaptation would increase to $14 trillion annually for the median sea level rise of 0.86 metres, and up to $27 trillion per year for 1.8 metres.” In that latter scenario, damage control and recovery “would account for 2.8% of global GDP in 2100.”
Breaking things down further, Jevrejeva and her team found that the richest countries “would suffer least, because of the high levels of protection infrastructure they already enjoy.” Upper-middle income countries like China, on the other hand, “would see the largest increase in flood costs.”
The greatest impacts, however, would fall on low-lying and small island states like The Maldives. Those countries “will be very easily affected, and the pressures on their natural resources and environment will become even greater,” Jevrejeva said.
“The cuts in greenhouse gas emissions already promised through the UN Framework Convention on Climate Change are not yet enough to achieve the 2.0ºC limit,” Climate News Net notes, “let alone the more stringent figure, and much deeper cuts will be needed.”