A Sentinel-2 satellite image on 20 May shows the Dutch province of Zeeland, including the port of Rotterdam, the largest seaport in Europe at the top right. Much of the region lies below sea level and depends on an intricate system of dikes, canals and dams to survive.
Credit: European Space Agency
Credit: European Space Agency
Climate change is causing oceans to rise faster than scientists’ most pessimistic forecasts, leading to earlier flood risks for coastal economies already struggling to adapt.
The revised estimates released Tuesday in Ocean Science affecting the two fifths of the earth’s population living near shorelines. Insured property worth trillions of dollars could pose an even greater danger from floods, superstorms and flood surges. The research suggests that countries should increase their greenhouse gas emissions even more than expected to keep sea levels in check.
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“This means that our carbon budget is even more depleted,” said Aslak Grinsted, a geophysicist at the University of Copenhagen who co-authored the research. Economies need to reduce another 200 billion tonnes of carbon – equivalent to about five years of global emissions – to stay within the thresholds set by previous forecasts, he said.
The warmer it gets, the faster the sea level rises. The sensitivity models of the future appear to be inconsistent with historical data.
Credit: Aslak Grinsted
The researchers built on the models of the United Nations Intergovernmental Panel on Climate Change, many of which take into account only the past 150 years, by incorporating data dating back several centuries. The new observations show that about half a meter of sea level rise by the end of the century can now be expected with only a rise of 0.5 degrees Celsius in temperatures. Oceans can rise more than 1 meter at 2 degrees Celsius, an orbit that can be easily transmitted under current climate policy.
“The models on which we are currently basing the prediction of sea level rise are not sensitive enough,” Grinsted said. “To make it clear, they do not hit the point when we compare it to the rate of sea level we see when we compare future scenarios with observations going back in time.”
The conclusions follow last month’s warning that rising temperatures have melted 28 billion tonnes of ice – equivalent to 100 meters of ice covering the whole of the UK – making the worst-case climate scenarios more likely. The new method of detecting change at sea level can help insurance companies, fixed developers and city planners to set up tidal defense systems.
“The scenarios we are now seeing with regard to sea level rise are too conservative – the sea seems by our method to be rising more than is believed by the current method,” Grinsted said, adding that his team at the Niels Bohr Institute. is in contact with the IPCC on recording the results in the sixth next year Assessment report.