In a first, study puts price tag on Sandy damage caused by sea-level rise

Almost 25,000 people in NJ were exposed to floods as a result of higher waters driven by human-caused warming, study says
Credit: U. S. Fish and Wildlife Service - Northeast Region via Creative Commons CC PDM 1.0
According to a new report, more than 10% of superstorm Sandy’s extreme flooding was the result of a 4-inch rise in sea level.

Sea-level rise that can be attributed to human-caused climate change caused roughly $4 billion of the damage wrought by superstorm Sandy in New Jersey, or about 13% of the total, noted a study published Tuesday.

That anthropogenic warming has been responsible for 4 inches of the sea-level rise in the New York-New Jersey area over the past century, and that increase worsened the storm surge that led to the destruction of thousands of homes and displacement of thousands of people, according to the study by the Princeton-based research group Climate Central, Rutgers University, the Stevens Institute of Technology and others.

Some 24,500 people and 16,700 homes in New Jersey were exposed to the storm in October 2012 as a result of the extra height of the ocean, the report said. Across the New York-New Jersey-Connecticut region, the damage attributable to the human-caused increase in sea level was estimated at $8.1 billion, also 13% of the approximately $62 billion that the storm cost the region.

Doug O’Malley, director of Environment New Jersey, called the new report “the research we’ve been waiting for” because it’s the first to prove that climate change made Sandy worse than it would otherwise have been.

“This research really provides a clear picture of how much more damaging Sandy was because of climate change,” he said. “Its impacts were measurably worse because of historic sea-level rise.”

Time to act is now

The report highlights the need to reduce carbon emissions as well as prepare for the effects of climate change, O’Malley said. And even though scientists say sea-level rise is locked in until at least the middle of the current century regardless of any mitigation efforts, that doesn’t lessen the need to curb emissions now, he said.

“If all we’re going to do to prepare for climate change is to build the dunes higher, we’re in for a sorry surprise,” he said. “We need to be working to reduce global warming pollution now so that in 2050, our coastal communities are still with us.”

It’s unlikely the report will create any new public support for climate-change mitigation or adaptation, O’Malley said, but the fact that it focuses on an event of historic ferocity may focus policymakers’ minds on the task ahead.

“It’s one thing to know about climate change, but it’s another thing to permanently make changes,” he said. “The public is not going to be riveted by these findings, but state decision makers should be.”

Powerful impact of merely 4 inches

Benjamin Strauss, CEO of Climate Central, said the apparently modest 4-inch rise in sea level had a devastating effect on the tri-state area during Sandy.

“Just a hands-width of sea-level rise from climate change caused more than 10% of the damage from Sandy’s towering flood waters,” Strauss said. “Human-caused sea-level rise is already making every coastal flood more destructive and costly. The costs of climate change are likely much greater than we appreciate today.”

The document follows a major state report released last month on how to prepare for climate change. That study estimated that seas at the Jersey Shore will rise 1 to 2 feet from 2000 levels by 2050, and by 2 to 5 feet by the end of the century, based on a scenario of moderate global emissions. One foot of sea-level rise will result in daily flooding or permanent inundation for 3,600 homes, rising to more than 11,000 homes if waters rise by 2 feet, that report said.

Chronic flooding already a threat

The report estimated that more than 60,000 homes statewide are already at risk of chronic flooding, and 2,600 of them were built or rebuilt since superstorm Sandy devastated the Shore in 2012. And that new report precedes the release of new rules under the Protecting Against Climate Threats process, in which the Department of Environmental Protection is expected to make it more difficult to build in flood-prone areas, and to place more responsibility on local government to take climate-adaptation measures.

In the study released Tuesday, the damage calculations would likely have been higher if researchers had also focused on whether climate change influenced Sandy’s track or increased the strength of its winds, the researchers said. “But this analysis confines its scope to a controlled, isolated picture of what we can say with high confidence, based on attributable sea-level rise alone,” the researchers said in a statement accompanying the report.

It noted other studies have so far found no evidence that Sandy’s intensity, size or unusual track were made more likely by climate change. And it said the report is a warning of more damage as sea-level rise accelerates in coming decades.

“This case study underscores that human-caused sea-level rise has contributed to damages associated with other past coastal floods and will increasingly aggravate damages in the future as sea levels continue to rise, driven by anthropogenic warming,” said the report, titled Economic Damages From Hurricane Sandy Attributable to Sea Level Rise Caused by Anthropogenic Climate Change published Tuesday in the journal Nature Communications.

It acknowledged that it is “notoriously challenging” to attribute human influence to single weather events. In this case, it based its conclusions on two independent modeling and budget-based approaches, which reached similar conclusions — and then modeled flood damage to produce a range of estimates of how much sea-level rise had contributed to Sandy’s damages.

Jeff Tittel, former director of the New Jersey Sierra Club, said the report is the first to calculate the damage caused by sea-level rise specifically during the storm. “The intensity of Sandy could have been made worse because of climate impacts but we don’t really know that,” he said. “What we do know is that because the seas and the bays have risen, that alone increased the damage by about 13%.”

He said the study should increase pressure on state and local policymakers to do more to cut carbon emissions, and to prepare for the effects of climate change, including sea-level rise.