Climate change is causing oceans to rise faster than scientists' most pessimistic predictions, resulting in earlier flood risks for coastal economies already struggling to adapt.
The revised estimates published in Tuesday Ocean Science impact on the two fifths of the world's population living near coasts. Trillion-dollar insured properties can be even more at risk from floods, superstorms, and tidal waves. The research suggests that countries will have to curb their greenhouse gas emissions even more than expected to keep sea levels under control.
“It means that our carbon budget is going to be even more depleted,” said Aslak Grinsted, a geophysicist at the University of Copenhagen who co-authored the study. Economies need to cut another 200 billion metric tons of carbon – equivalent to about five years of global emissions – to stay within the thresholds of previous forecasts, he said.
The researchers built on the models of the United Nations Intergovernmental Panel on Climate Change, many of which only consider the last 150 years, by including data dating back several centuries. The new observations show that a sea rise of about half a meter can be expected by the end of the century, with a temperature rise of only 0.5 degrees Celsius. Oceans can rise more than 1 meter at 2 degrees Celsius, a trajectory that is easy to pass under current climate policy.
"The models on which we currently base our sea level rise forecasts are not sensitive enough," said Grinsted. "To put it plainly, they are not good enough when we compare them to the rate of sea level rise that we see when we compare future scenarios with observations going back in time."
Follow the conclusions warning from last month that rising temperatures have melted 28 trillion tons of ice – equivalent to a 100m thick layer of ice covering the entire UK – making the worst climate scenarios more likely. The new methodology for sea level change tracking could help insurance companies, real estate developers and city planners set up tidal defense systems.
"The scenarios we are seeing now regarding sea level rise are too conservative – the sea looks to rise more according to our method than is assumed with the current method," Grinsted said, adding that his team at the Niels Bohr Institute is in contact with the IPCC about incorporating the results into next year's sixth assessment report.
Copyright 2021 Bloomberg.
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