As for the next 30 years, we’re going to see sea level rise. That horse has left the barn.”

Professor Benjamin Greenstein, dean of the Roger Williams University School of Social and Natural Sciences

The Sea Level Report – at a glance

Published by the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Department of Commerce, the 2022 Sea Level Rise Technical Report was produced by a task force that includes numerous federal agencies. It focused in four key areas:

1. The Next 30 Years: “Sea level along the U.S. coastline is projected to rise, on average, 10 - 12 inches (0.25 - 0.30 meters) in the next 30 years (2020 - 2050), which will be as much as the rise measured over the last 100 years (1920 - 2020).”

2. More Damaging Flooding: “Sea level rise will create a profound shift in coastal flooding over the next 30 years by causing tide and storm surge heights to increase and reach further inland. By 2050, “moderate” (typically damaging) flooding is expected to occur, on average, more than 10 times as often as it does today, and can be intensified by local factors.”

3. Emissions Matter: “Current and future emissions matter. About 2 feet (0.6 meters) of sea level rise along the U.S. coastline is increasingly likely between 2020 and 2100 because of emissions to date. Failing to curb future emissions could cause an additional 1.5 - 5 feet (0.5 - 1.5 meters) of rise for a total of 3.5 - 7 feet (1.1 - 2.1 meters) by the end of this century.”

4. Continual Tracking: “Continuously tracking how and why sea level is changing is an important part of informing plans for adaptation. Our ability to monitor and understand the individual factors that contribute to sea level rise allows us to track sea level changes in a way that has never before been possible (e.g., using satellites to track global ocean levels and ice sheet thickness). Ongoing and expanded monitoring will be critical as sea levels continue to rise.”

Sea levels will rise about a foot along the East Coast of the United States in the next three decades, bringing as much sea level rise in the next 30 years as took place in the previous century.

This is one of the key findings in a report released last month by a team of scientists representing numerous government agencies. The “2022 Sea Level Rise Technical Report” also predicts there will be far more frequent and damaging flooding throughout coastal areas, with significant increases in both moderate and major flood events.

The report generated widespread attention when released, with many of the nation’s top newspapers sharing details with readers. And though the report might have been surprising to some, it was not for many scientists, marine biologists or civil engineers who have been talking about and thinking about this for years.

This group includes Professor Benjamin Greenstein, dean of the School of Social and Natural Sciences at Roger Williams University. He was not surprised to read about the foot of relative sea level rise. What stood out to him above all else was the level of certainty in the predictions.

“What’s most compelling in this report, is that they’re narrowing their range of predictions,” Greenstein said. “Their models are beginning to converge, and they have much narrower ranges of prediction.”

In previous analysis of sea level rise, the projections were more wide-ranging — seas could be rising 1 to 3 feet. In this report, the models are much more exact. The new report predicts an average of 10 to 14 inches of rise for the East Coast by 2050; 14 to 18 inches for the Gulf Coast; 4 to 8 inches for the West Coast; 8 to 10 inches for the Caribbean.

Greenstein looked deeper than the report’s summary and examined some of the underlying data. He said the data is getting better, the models more certain.

He also believes the predictions for the next 30 years are close to a certainty, and nothing in human behavior is going to change those outcomes.

“As for the next 30 years, we’re going to see sea level rise. That horse has left the barn,” he said.

What might still change are the predictions for the rest of the century. The report suggests there could be an additional 1 to 5 feet of sea level rise by 2100.

An East Coast thing

Folks living around here will note that the models predict much higher sea level rise in this part of the country than in other areas, such as the West Coast. As a professor of geology, Greenstein said it’s important to understand the concept of “relative” sea level rise, which can be dramatically impacted by the spin of the Earth, geological forces and the shifting of the world’s tectonic plates.

“When we talk about sea level, we’re always talking about relative sea level,” he said. “The sea level can go up, but the land can also go down. So the ‘relative’ sea level may be impacted by both.”

This helps explain why the East and Gulf Coasts are predicted to see far greater impact from rising seas.

Ice sheet variability

One aspect of the report did catch Dean Greenstein by surprise. When reading through the analysis, he noted that the scientists do not include any factor for melting of the polar glaciers.

“They didn’t work in any of the ice sheet variability. It is not factored into their projections,” he said. The report mentions the polar glaciers and talks about how a rise in global temperatures might impact them, but concludes only: “How much to trigger them is unknown.”

So put a pin in that thought, as the polar caps seem to be a wild card.

Brace for the floods

Many people look at the coastline and wonder why another 12 inches of water is anything to worry about, especially when roads, bridges and homes sit several feet about sea level. The problems don’t come every day; they come on bad weather days — or mild weather days combined with the right forces of tide and wind.

The report says this about flooding: “Sea level rise will create a profound shift in coastal flooding over the next 30 years by causing tide and storm surge heights to increase and reach further inland. By 2050, ‘moderate’ (typically damaging) flooding is expected to occur, on average, more than 10 times as often as it does today, and can be intensified by local factors.”

It goes on to clarify that moderate flooding events will occur more frequently in 2050 (4 times per year) than minor flooding events (3 times per year) occur today.

Major flooding events, described as “destructive,” will occur about five times more frequently than they do today.

“We’re going to be getting moderate flooding at the rate we’re now getting nuisance flooding,” Greenstein said. “Geologically, a foot is a lot, especially for an area like this — very low-lying communities.”

Salt water will wash into freshwater bodies more frequently. The ecology of marshes may change dramatically. Coastal property owners may cringe any time a strong storm heads this way — which also seems to be a far more frequent occurrence than it once was.

What’s next

Greenstein looks at the passage of time differently than most. He likes to remind that human perceptions of times and geological scales of time are vastly different. In geological terms, seas have been rising and falling for millions of years.

“I taught a class in historical geology,” he said. “About 350 million years ago, CO2 levels were 20 times higher than they are today. At one point, sea levels were so high you could have paddled a canoe from the Gulf of Mexico to the Arctic Ocean.” In other words, as seas have risen and fallen, the biosphere has found ways to adapt. There is a big difference this time, however — namely, 6 billion-plus people, a majority of whom live close to coastlines.

Greestein believes this new report should be taken seriously and should trigger sober evaluation and actions around the globe. He stands behind the “horse has left the barn” description for the next three decades, but he believes changes in geopolitical policies and human behaviors today can still impact life a century from now.

“The increase in the rate of sea level is not a surprise. That’s what you would expect,” he said, referring to centuries of burning fossil fuels at increasingly high rates and the steady rise in CO2 emissions around the globe. He likens the whole thing to a machine that slowly cranked to life and is now churning at full speed.

“This is a system that takes a while to get going. It also takes equally long to go the other way,” he said.

This is one reason he’s so devoted to his career and how it impacts young minds. “At Roger Williams, we’re talking about science, policy, politics, social inequity … We’re working to educate citizens, so they have an appreciation for the numerous lenses needed to see their world.”

He said the world clearly needs engineers, but it also needs thinkers and problem-solvers. “The combination of the liberal arts and engagement and social justice issues are salient … These are complex problems, and they are best solved by people who have a liberal arts background,” he said.

To read the full 2022 Sea Level Rise Technical Report, go to: https://oceanservice.noaa.gov/hazards/sealevelrise/sealevelrise-tech-report.html