Magazine article Oceanus

More Floods and Faster-Rising Sea Levels

Magazine article Oceanus

More Floods and Faster-Rising Sea Levels

Article excerpt

JeffDonnelly can't help but get his hands dirty in his work. You can often find him poking long, plastic cylinders into coastal marshes, or beaches, or the bottoms of lagoons- like an apple corer into an apple-to extract multi-layered plugs of mud and sediments. That's his paydirt.

The layers built up over time, some of them forming as sea levels rose, or when hurricanes struck or storm surges flooded coastlines. Donnelly, a coastal geologist at Woods Hole Oceanographic Institution, examines the cores to reconstruct a history of geologic events on the coast. The deeper the cores, the further Donnelly can travel into the past.

The past puts the present, and the future, into context in two studies Donnelly took part in that received a lot of media attention. Both were published in 2016 in the journal Proceedings of the National Academy of Sciences.

The first study showed that global sea level rose faster in the 20th century than at any other time in the last 2,700 years. The rise was particularly fast over the last two decades, said Robert Kopp of Rutgers University, the study's lead author.

For the study, scientists at Rutgers and Tufts University compiled a new database of geological sea-level records, including Donnelly's, from marshes, coral atolls, and archaeological sites from around the world. The records spanned the last 3,000 years. They also tapped 66 tide-gauge records from the last 300 years.

A statistical analysis of the data showed that global sea level rose by about 5.5 inches from 1900 to 2000-a substantial increase, especially for vulnerable, low-lying coastal areas. What's more, in the absence of global warming, the study showed that Earth's sea level likely would have been lower and might actually have decreased.

The study also predicted that if the world continues to rely heavily on fossil fuel, global sea level will rise by 1. …

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