Study Shows Rapid 18th Century Sea-Level Rise on Atlantic Coast

Written by Soorya Kiran on March 5, 2020. Posted in Current News

east coast atlantic ocean

A study by the University of York found evidence for a period of enhanced pre-industrial sea-level rise of about 2-3 millimeters per year in three locations — Nova Scotia, Maine, and Connecticut, which was largely natural, without any human constructions or man-made factors.

These three locations are partly related to the North Atlantic Oscillation – a large-scale atmospheric pressure see-saw over the North Atlantic region – and to periods of enhanced ice melt in the Arctic, said the authors of the study, whose findings are published in Geophysical Research Letters.

The authors of the study say cities like New York and Boston will have to take into cognizance this natural variability that may affect these cities in the future as well.

The team found sea-level reconstructions based on salt-marsh sediments from the Atlantic coast and from microscopic salt-marsh fossils.

Salt-marshes are good “archives” of sea levels as they contain several meters of sediment which contains data going back hundreds of years.

Faster than the global average

Previous studies have shown that, since the 1950s, rates of sea-level rise along the Atlantic coast of North America were faster than the global average – leading to this region coming to be known as a sea-level rise “hotspot.”

However, lead author Prof Roland Gehrels, from the University of York’s Department of Environment and Geography, said this earlier rapid episode of sea-level rise in the 18th Century wasn’t known before.

To find out what global warming is doing to sea levels today, the team examined the base level from historical times.

“In the 20th century, we see rates of up to three or four millimeters per year, faster than in any century in at least the last 3000 years. In the 18th Century they were slightly slower, but still much quicker than you would expect for the Little Ice Age, partly because the Arctic was relatively warm during the 18th Century,” he noted.

No human factors in the pre-industrial era

It was a pre-industrial phenomenon, so there were no anthropogenic forces – or human influences, he explained. In the 20th century, they might have played a key role but well before the industrialization, those rapid episodes of sea-level rise on the northeast coast of North America in the 18th Century might have been caused due to natural causes, he said.

Read rest at IB Times

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