There Will Be Floods: Aerial imagery by the National Oceanic and Atmospheric Administration shows flooded houses on Breezy Point following Superstorm Sandy. Sea level rise will make scenes like this more common in New Jersey.

The seas are rising. Robert Kopp, a Rutgers climate scientist who studies sea level change, isn’t here to tell you what to do. But he is here to tell you that the entire state is likely to suffer the effects of sea level rise: whether to do anything about it is up to elected officials. But just so you know, a certain amount of the state is going to be underwater before the century is out.

So, exactly how much is the sea going to rise in New Jersey? “The question you asked does not permit an easy answer,” Kopp explains. But it does permit a complicated one.

Kopp will discuss managing coastal risk in an age of sea level rise at a Science on Saturday event at the Princeton Plasma Physics Laboratory on Saturday, March 2, at 9:30 a.m. For more information on the free lecture, visit www.pppl.gov.

Kopp directs Rutgers University’s Coastal Climate Risk & Resilience initiative as well as the Climate Impact Lab, which is a group of scientists and experts from multiple institutions who are working to assess the economic impacts of climate change.

In his own research, Kopp focuses on sea level change and the economy.

Bob Kopp of Rutgers University.

When discussing the future effects of climate change and sea level rise, Kopp speaks in the language of probabilities rather than certainties — that’s because there are some variables of the climate system that scientists do not yet fully understand. Human carbon emissions also play a big part in determining sea level rise — curbing them could mean stalling the advance of the seas.

The picture looks different depending on the time scale. Kopp says it is very likely that the sea level will rise between one and two feet by 2050. Beyond that, uncertainty grows. “Some of it depends on how much greenhouse gas we emit, which is something we control,” he says. “And some of it on the physics of ice sheets, which we are learning about but can’t control.”

The picture is much more manageable if humanity manages to reduce its greenhouse gas emissions. In a 100-year time frame that would mean two or three feet of sea level rise. If we allow emissions to go unchecked, he says, that figure could be from two-and-a-half to four-and-a-half feet if we are relatively lucky, and between four-and-a-half to eight-and-a-half feet if we are relatively unlucky. If we are supremely unlucky, the seas on New Jersey’s coastline could be a full 10 feet higher than they are now. (Some of the variability depends on our current limited understanding of how ice sheets and oceans interact.)

No one reading this article at the time of its publication will be alive by the time Kopp’s predictions will either come true or not. Part of the difficulty of preparing for a future of higher seas is that we are making decisions today that will have consequences far into the future.

For example, authorities are currently working to build new rail tunnels under the Hudson River between New York and New Jersey. The existing tunnels are nearly a century old and were damaged in Superstorm Sandy. (U.S. 1, December 5, 2018.) It’s reasonable to assume the new tunnel will be around in 100 years and will have to deal with whatever new climate conditions exist then. “If we think about investments like that, or zoning decisions about whether and how developments will grow, we are making decisions affecting our children and grandchildren, and we are making them in a situation where we can say with relative confidence what will happen over the next 30 years but not the next 80,” he says.

Kopp says we should not ignore the high end possibilities, but not take them as a given, either. The downside of planning for an eight-foot sea level rise would be that it is very expensive, and those funds could be spent to better effect elsewhere if the sea level rise does not prove to be that extreme. Kopp says one option is to plan and build for a lower level sea level rise, but to have contingency plans for what to do if it starts to rise more quickly. Kopp calls this “adaptive management contingency planning.”

Meanwhile, investing in the study of climate change will give us a better idea of what to expect, and reducing emissions as much as possible will help manage the scope of the problem.

A 10-foot sea level rise would put New Jersey’s coastal cities underwater and effectively erase the barrier islands from the map. But even under the low-end predictions, New Jersey is going to be a very different place than it is now.

Storm Surge: Ocean City floods after a winter storm in 2013. Climate scientists say flood-prone areas will become less defendable as the century goes on.

Rutgers publishes a website at www.njfloodmapper.org that shows how the coastline will be different under different amounts of sea level rise. At three feet, large parts of Atlantic City and other coastal cities are permanently underwater. The other side of the state is not safe either, since the Delaware River will rise along with the ocean. The marshy area southeast of Trenton will be inundated, and catastrophic floods everywhere will be more frequent.

Higher seas also mean that coastal storms can penetrate farther inland. Areas that are influenced by tides or hurricanes have to worry about sea level rise. “That’s essentially all of New Jersey,” Kopp says.

A 10-foot sea level rise, on the other hand, is possible if high greenhouse gas emissions continue and arctic ice sheets prove to be unstable. “We are talking about permanently flooding areas home to about 600,000 people in New Jersey — and permanently flooding areas home to about $190 billion of property,” Kopp says.

Scientists have observed that the sea level has been rising worldwide for centuries. Interestingly, the rise will be faster in New Jersey than elsewhere on the planet. Kopp says Earth’s gravitational field, melting ice sheets sucking water towards themselves, and changes in ocean currents and winds mean that New Jersey will rise faster than the overall global rate.

Even in areas that are not put underwater, flooding will be more of a problem. “When you raise the sea level, that means it requires less of a tide or a storm surge to cause the same amount of flooding. Over the last 70 years, we’ve already seen the frequency of minor flooding has increased by a factor of 10.”

Sandy, he says, was an example of the damage sea level rise has already done. A study by Palmer Square-based Climate Central estimates that Sandy caused $5 billion more damage than it would have absent human-caused sea level rise.

Given that some amount of sea level rise is inevitable, what should we do about it? Kopp says one option is to ignore the problem, and that some communities have apparently embraced this approach. “Some areas actually gentrified and put more valuable property close to the ocean,” he says.

Another option is to modify communities to accommodate more frequent flooding, and that includes engineering solutions such as elevating houses. “This isn’t something that can be effective one house at a time,” Kopp warns.

In some areas, where there is a great deal of valuable property on solid ground rather than a barrier island, hard protective structures such as berms and tidal barriers are viable options.

Flooding can also be mitigated by improving natural defenses, such as expanding tidal marshes and building oyster beds. Oyster beds absorb wave energy, so they can help reduce the impact of storms. A project is currently under way to create a giant oyster reef in Jamaica Bay, near New York.

Another option is to abandon areas that will surely be lost to rising seawater. “If we have an area that it is clear it’s going to be much harder to inhabit in 50 years, we could plan to gradually relocate away from those areas,” he says.

Although much of the decision making revolves around risk, chance, and uncertainty, there are several hard facts to deal with. One is that sea level rise is definitely happening, to one degree or another. “It is certain to happen because among other things, it has already happened,” Kopp says. “It’s been happening for thousands of years but at an accelerated rate since the 19th century, and a large part of that is due to human activity.” The sea has risen between three and six inches in the last 25 years, since satellites began monitoring it. The rate is accelerating.

The physics of climate change also make sea level rise inevitable, he says. Carbon dioxide trapping heat in the ocean and melting glaciers will certainly cause the sea level to rise some amount.

Kopp says estimates vary as to how much of sea level rise is due to human activity. Low-end estimates place human impact at 40 percent, but Kopp says the figure is probably closer to 70 or 80 percent.

Kopp is co-director of two different groups. The first is the Coastal Climate Risk and Resilience Initiative, which is an interdisciplinary team of graduate students in the natural sciences, social sciences, engineering, and urban planning along with coastal stakeholders. The goal is to train the graduate students in studying and responding to the dangers of sea level rise.

The Climate Impact Lab includes 30 researchers from Berkeley, the University of Chicago, Rutgers, and the Rhodium Group, an independent economic and policy research organization based in new York City. The group is also an interdisciplinary team. It is using a “big data” approach to studying the impacts of climate change in the present and in the future.

“The lab’s researchers combine historical socioeconomic and climate data, allowing the team to discover how a changing climate has impacted humanity — from the ways in which extended droughts have affected agricultural productivity in California to the ways in which heat waves have impacted mortality in India and labor productivity in China. Understanding these relationships allows the Lab to produce evidence-based insights about the real-world impacts of future climate change using projections of temperature, precipitation, humidity, and sea-level changes around the world at a subnational scale — from U.S. counties to Chinese provinces,” the group’s website, www.impactlab.org, says.

Kopp warns that efforts like this will need a great deal of support if we are to understand and respond to the risks posed by climate change in the future.

Kopp grew up in the Washington D.C. suburbs in Maryland, where his mother worked in state government and his father was an attorney for the State Department. At the beginning of his academic career he interested in the origins of life on earth, and this interest led him to study the weather on Mars. He wanted to know whether Mars was ever inhabitable, and if so, what its climate was like billions of years ago — this would have implications for the long term evolution of life on earth. He holds a bachelor of science in geophysical sciences from the University of Chicago, Class of 2002, and master’s and doctoral degrees in geobiology from Caltech. He has been at Rutgers since 2011.

After studying Mars for five years, Kopp chose to transfer the skills he had learned to a different planet and began studying climate change on Earth. Kopp calls climate change one of the most pressing issues of our time.

“We can observe sea level rise happening globally, and in New Jersey, and unless we severely reduce our emissions, that is going to get worse,” Kopp says. “We need to be having a dialog and we need it to be informed by the best available science.”

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