On a beautiful fall afternoon a few weeks ago, Anthony Broccoli stood on a nature trail in South Bound Brook, along the banks of the slowly meandering Raritan River. As a professor of atmospheric science at Rutgers, his job is to study long-term changes in New Jersey’s climate and makes computer models of what the weather could be like in the future. That might sound esoteric, but the story of this place, he explained, is a perfect example of why predictions matter.
Just a short distance upstream from where he stood was the Raritan-Millstone Water Treatment Plant, a major source of water for much of Central New Jersey. The plant is located in a vulnerable spot, near the intersection of two rivers. So after it flooded during a tropical storm in the early 1970s, its managers decided to build some extra fortifications.
“They used what was then the estimate of the 500-year flood to determine the height of the berm,” said Broccoli. “However, the concept of a 500-year flood implies that nothing is changing, and that we can look at past records of water levels, and that will tell us what to expect in the future.”
The problem, he said, is that lots of things were changing, including increased development in the area and new weather patterns that brought more frequent, heavy rainstorms. So what seemed like adequate protection back in 1971 was no longer enough three decades later. When Hurricane Floyd hit in 1999, the water level in the Millstone and Raritan Rivers rose so high that it topped the berm and began to flood the plant. The workers had to be evacuated by helicopter, and the plant was closed down for a couple of weeks afterward as a result.
Broccoli explained that basing important planning decisions on experience has historically been a reasonably good assumption, but in a changing climate, that assumption is no longer valid. “Events that may have been very rare in the past could become less rare in the future,” he said. And he thinks it’s a lesson New Jersey would be wise to remember as it goes about rebuilding its coast.
Climate models predict more intense storms, and sea levels from Sea Bright to Cape May could rise as much as three-and-a-half feet by the end of the century, compounded by the fact that the Jersey Shore is slowly sinking. So the sort of flooding that took place during Sandy could become much more common.
But while other coastal states are considering weather predictions up to a hundred years in the future in their current planning efforts, New Jersey has so far been more focused on the short-term recovery. Beyond setting baseline regulations, the Christie administration has left many of the planning decisions up to individual municipalities in a nod to the strong tradition of home rule that exists in the Garden State.