Sea-level rise will bring 9-foot floods to New York City over the next century

Hurricane Sandy Sea-level rise Brooklyn Battery Tunnel

In a new study, scientists predict that New York City will have 9-foot floods over the next century.

The flood will be 17 times more frequently, and as intense as that produced by 2012’s Superstorm Sandy. The finding is published in the Proceedings of the National Academy of Sciences.

Researchers from the Rutgers University, Princeton University and the Woods Hole Oceanographic Institution conducted the study.

The research is based on a combination of historical data and computer model projections. The historical data consist of tidal gauge records taken from New York City, going back to 1856, and geological records from the same area going back two millennia.

The scientists ask the question: How frequent will floods like that produced by Sandy be in the future?

Earlier research had shown a 20-fold increase in the frequency of extreme floods, primarily as a result of sea-level rise, between the historic period from 850 to 1850 and the late 20th century.

The historic sea-level rise was largely due to natural effects, like the slow sinking of the land in the mid-Atlantic region in response to the end of the last ice age; but over the late 20th century, human-caused climate change came to dominate sea-level rise.

In the paper, the authors reported that floods as intense as Sandy’s would have occurred about once every 400 years under the sea-level rise conditions of the year 2000,

Furthermore, over the 21st century, floods are expected to be about 4 times more probable due to an acceleration in the rate of sea-level rise.

Researchers suggest that things might be going to get worse by 2100. If nothing changes with hurricanes, sea-level rise alone will increase the frequency of Sandy-like events by 2100.

In addition, the size, intensity, and tracks of hurricanes may change.

Through analysis, researchers found that these changes may lead to a more modest three-fold increase in flood probability, but may also break badly against New York City, making Sandy’s flood 17 times more probable.

Researchers conclude that temperature and sea level will be related in the future as they have been over the past two thousand years. Things will be worse by 2100, and it’s just a question of how much worse it will get. We need to get prepared.

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Citation: Lin N, et al. (2016). Hurricane Sandy’s flood frequency increasing from year 1800 to 2100. Proceedings of the National Academy of Sciences, published online. DOI:10.1073/pnas.1604386113.
Figure legend: This image is credited to MTA.