July 18, 2018 | ° F

New Jersey faces future flooding due to accelerated sea level rise

Throughout the world, sea levels are rising at an average of 3 millimeters per year, said Robert Kopp, an associate professor in the Department of Earth and Planetary Sciences at Rutgers.

Kopp is part of a research team composed of members from Harvard University and Rutgers University focusing on sea levels. Many sources have been found to contribute to the rising tides, including global climate change, he said.

“Sea level rises at a different rate everywhere on the planet,” he said. “The physical processes causing sea levels to rise — some are global and some are local. Currently, the mean is about 3 millimeters per year.”

Kenneth Miller, a distinguished professor in the Department of Earth and Planetary Sciences, said the seas near New Jersey are rising at a rate of 4 or 5 millimeters per year — higher than the global average.

This is due to four effects. The first is a local effect, specifically attributed to the sediment on which New Jersey beaches sits. While nearby cities sit on solid rock, New Jersey sits on much softer sand.

Miller said if someone went to a beach and got a bucket full of sand, a layer of water would appear on top of the sand by the time he or she returned home. He said the sand compacts with time, forcing the water contained within to move toward the top.

This effect is happening throughout New Jersey, he said. The other regional effect is the result of an ice sheet that existed in Canada approximately 20,000 years ago.

“That ice sheet melted away, so the area under Canada started bouncing up,” Miller said. “Imagine it’s like a trampoline. But there is a see-saw effect — [if] that area goes up, we start sinking.”

This effect, known as glacial isostatic adjustment, is a regional one causing New Jersey to sink, Miller said. Even though it has no effect on the sea levels on its own, it makes the ocean levels appear to rise faster than in other locations.

The other two effects are global, Kopp said. One is the melting of ice sheets and mountain glaciers.

The last effect is the heating of the ocean. Warmer ocean water takes up more space through a process known as thermal expansion.

Carling Hay, a postdoctoral fellow at the Department of Earth and Planetary Sciences at Harvard, said no data can be provided at the moment for how quickly oceanic temperatures are rising but he did say oceans are rising at faster rates now compared to 100 years ago.

“Previous estimates of global sea level rise from 1900-1980 were 1-2 millimeters per year,” she said. “We agree with the estimate — what we’re suggesting is they were rising at 1.2 millimeters per year.”

The accelerating rate is much higher than previous estimates, Hay said.

Global warming is one factor in the increased rate, Miller said. He said satellites and tide gauges help track sea level rise around the planet.

Predicting how the oceans will act in the future is difficult, Hay said. There are projections that go from 50 to 100 years into the future, but some factors are still uncertain.

“The main uncertainty is how the ice sheet and mountain glaciers will melt,” she said.

Understanding how climate change would impact the oceans was important, Kopp said. He said analyzing the economy and how it would be impacted over the next century was part of the team’s next step.

Some areas of the world would likely flood permanently, he said. More important than that would be how the rising sea levels interacted with large storms.

“During Sandy, the seas were a foot higher than they were before, so approximately 100,000 more people were exposed to the storm,” he said.

Miller said Hurricane Sandy was no longer classified as a hurricane at the time it hit New Jersey.

Certain parts of the country could previously see a major flood event once every 100 years, Kopp said. Soon, those parts could see an event once every 10 years.

The team estimates the ocean by the Jersey Shore will be at least 13 to 18 inches higher than it is now by 2050. During the 20th century, Atlantic City saw the ocean rise 18 inches, he said.

Precautions could be taken to minimize the damage, Miller said. Those who live on the coast will have to raise their houses by several feet to protect them from storms and flooding.

“We will have to continue to pump sand onto the beaches, [or] what we call ‘nourish’ the beaches,” he said. “We’ll have to be more aware of what we put in [our] infrastructure.”

Leaving unsustainable areas was another option, Kopp said. So was building a large sea wall, or what he called a “hard defense.”

 A major reduction in greenhouse gasses would also lengthen how long it took for the sea to rise one foot, Miller said. By 2055, it is likely the sea will rise nearly two feet. Reducing emissions could push that off until 2075.

Many options exist, Kopp said. He said the important thing is to acknowledge sea levels are rising.

Miller said at the current rate, the planet was moving toward an ice-free Arctic every September and reduced Arctic Sea ice.

“There won’t be a Miami beach,” he said. “It’s not Armageddon, but by 2100 we are going to face a different New Jersey.”

Nikhilesh De

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