State Analysis Points to Eventual Seven Feet of Sea Level Rise at the Battery
A new report from the New York State Climate Impacts Assessment, a science-based investigation into how global warming is affecting New York’s local communities, ecosystems, and economy, has dire implications for Lower Manhattan.
In the report, titled “Understanding and Preparing for Our Changing Climate,” the research team notes that the rate of local sea level rise, as quantified by a tide gauge at the Battery (just off the southern tip of Lower Manhattan), averaged about one-tenth of an inch per year between 1856 and 2022, or slightly less than a foot over the last century. But the report cautions that this is a conservative statement and notes that the rate of increase is accelerating, and from 1920 to 2022 was double the global average.
Projecting these trends forward, while factoring in multiple global drivers of climate change such as glacial melt and sea level rise, the team predicts that in the next decade, water levels at the coastline of the Battery could rise nearly as much as they did in the previous 100 years, increasing seven to 11 inches by the 2030s.
Longer term, the report predicts that by mid-century, sea levels surrounding Lower Manhattan could reach levels 14 to 19 inches higher than the study’s baseline (an average of the years 1995 through 2014) and then jump 25 to 39 inches in the 2080s. By the end of this century, the same models peg local sea level rise to 30 to 50 inches higher than the comparison point, with a rise of 47 to 89 inches by 2150.
These increases translate into more frequent flood events, in a form of inundation known as “high-tide flooding.” Often referred to as “nuisance” or “sunny day” flooding, it is unrelated to storms and caused by strong high tides during the full and new moons, often exacerbated by wind and shifts of ocean currents.
“While New York City currently experiences approximately ten high-tide floods per year as measured at the Battery, that number could rise to 60–85 days by the 2040s,” the report notes. “This projection means chronic flooding could affect low-lying coastal neighborhoods once a week or more.”
The $169-million Battery Coastal Resilience project, which completed its design process last year and is expected to break ground shortly, aims to address these concerns. But if the worst-case predictions contained in the Climate Impacts Assessment prove accurate, the five feet of additional elevation envisioned by the Battery Coastal Resilience designs may offer only a limited reprieve. The seven feet-plus of additional water predicted by this report for the mid-22nd century would overtop these barriers by more than two feet several times each week.