UN says emissions caps can hardly hold back flooding

Source:AFP Published: 2019/11/5 20:33:40

Just as an oil tanker steaming ahead at full speed cannot stop immediately, so the dramatic rise in sea levels will continue even if the world manages to slash greenhouse gas emissions to zero by 2030, experts warned in a study published on Monday.

A photo taken by a drone shows a stunning view of Alag Lake in Dulan County, Northwest China's Qinghai Province. The lake, with an average elevation of 4,099 meters, is a major inland lake in the upper reaches of the Qaidam River and also an important habitat for wildlife. The river channels formed by the melting of snow and ice in the mountains creates spectacular scenes. (Photo: China News Service/Chai Dicheng)

Emissions between 2015, when the Paris climate change accord was thrashed out, and 2030 would be enough to raise levels by eight centimeters by 2100, according to research by experts based in Germany.

They would rise by 20 centimeters by 2300 in comparison with the reference period of 1986-2005, according to the study published in the Proceedings of the National Academy of Sciences (PNAS).

In total, sea level can be expected to raise by at least a meter by 2300 in the extremely unlikely event that greenhouse gas emissions fall to zero in the next 11 years.

And that may be a conservative estimate: UN-backed scientists are already predicting an increase in water levels of between 26 centimeters and 77 centimeters by the end of this century alone.  

A full quarter of that one-meter rise by 2030 will be due to emissions from China, the United States, the European Union, Russia and India in the preceding 40 years, the authors of the latest report concluded.

By comparison, oceans rose by around 20 centimeters in the 20th century.

The goal of the study, co-author Alexander Nauels of the Climate Analytics institute in Berlin told AFP, was to show that current emissions will have a clear effect on rising sea levels that will be felt over the next 200 years.

"We all focus on the 21st century," he said, warning that "sometimes that can create the false impression that after the 21st century nothing else will happen."

Sea level rise is due to a number of complex phenomena that can play out over extremely long time scales, making its study difficult. It is still unclear why Antarctic ice is melting more slowly than in Greenland.  

"When you're looking into the sea level rise problem, it's a very slow and responding system," said Nauels.

"A centimeter doesn't sound like much but it's actually a lot," he added.

In a report published last year, experts from the Intergovernmental Panel on Climate Change (IPCC) said reducing the rise in sea level by 10 centimeters would save 10 million people in coastal areas from being exposed to flooding, storm surges and other risks. 

Coastal areas currently home to 300 million people will be vulnerable by 2050 to flooding made worse by climate change, no matter how aggressively humanity curbs carbon emissions, scientists have warned.

In the second half of the 21st century and beyond, however, choices made today will determine whether the global coastlines on maps today will remain recognizable to future generations, they reported in the journal Nature Communications.   

Destructive storm surges fuelled by increasingly powerful cyclones and rising seas will hit Asia hardest, according to the study.

More than two-thirds of the populations at risk are in China, Bangladesh, India, Vietnam, Indonesia and Thailand.

Newspaper headline: Sea level rise now irreversible

Posted in: AMERICAS

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