Warming temperatures, heavier rainfall, and rising seas — these are some of the climate-related effects in store for the Big Apple in the coming decade.
Rising sea level is one of the most worrisome issues facing New York City.
With so many people living right on the coast, an increase of just a few inches could be disastrous.
Unfortunately, the new report predicts sea level to rise by anywhere from 11 to 21 inches by the 2050s, and 18 to 39 inches by the 2080s. By the end of the century, sea level could be six feet higher than it is today.
In order to plan ahead, it’s important to know which areas are most at risk of flooding under these scenarios. The New York City Panel on Climate Change created this map to show which parts of the city might flood at different points in the century.
The map is based on the hypothetical “100-year flood zone” — the land that has a 1 per cent chance of being flooded this year. (For comparison, the storm surge brought on by Hurricane Sandy was bigger than the predicted 500-year flood, or a flood with a 0.5 per cent chance of happening.)
The size of a 100-year flood zone changes depending on how high sea level is expected to be in a given year — as sea level rises, more and more land will be flooded with the same storm, because of the extra water from the sea level rising.
For each time period shown on the map — the 2020s, 2050s, 2080s, and 2100s — sea level is expected to rise a little higher, pushing the floodwaters a little further inland.
At today’s sea level, the 100-year flood zone is 50 square miles — that means the Federal Emergency Management Agency (FEMA) estimates that there’s currently a 1 per cent chance of a flood that would inundate 50 square miles of land in New York City.
If we assume 10 inches of sea-level rise in the 2020s (a high estimate, but a good way to play it safe), the 100-year floodplain grows to 59 square miles — in other words, the higher sea level would mean the same sized flood would inundate 59 square miles, instead of 50. This flood zone becomes 72 square miles in the 2050s, 85 square miles in the 2080s, and 91 square miles in the 2100s as sea level continues to rise.
Planning for a 100-year flood can help policy-makers plan for worse scenarios than are likely to happen. And assuming high amounts of sea-level rise can help make their plans even safer. This map assumes 10 inches of sea-level rise by the 2020s, 30 inches by the 2050s, 58 inches by the 2080s, and 75 inches by the end of the century. The map is colour-coded to show which regions correspond to which scenario.
It’s important to note that this map only takes sea-level rise into account when mapping 100-year flood zones. In reality, climate change will also likely increase the frequency and intensity of severe weather events, like hurricanes — the kinds of storms that cause floods in the first place. If the changes in these weather events were factored in, the flood zones on the map might be even bigger.
Based on this map, the report’s authors note that Queens is the borough with the most land at risk of flooding. Lower, flatter coastlines in Brooklyn and Queens could put these areas at greater risk than Manhattan, which has steeper shores.
The authors stress that the map provides estimates only — it would be difficult to provide exact flood boundaries because of variability in the city’s coastlines and the manmade structures on the New York City shores. But the report does warn that flooding in the city could increase by anywhere from two to 15 times its current frequency and intensity throughout the century.
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