New York City faces increased flood risk due to climate change

New Scientist : Although the flooding and damage that Hurricane Sandy wreaked on New York City three years ago broke records, such storms may becoming much more frequent. The reason has to do with the higher sea levels and increasing severity of tropical cyclones associated with global warming. To determine how much human activities may be to blame, Benjamin Horton of Rutgers University in New Jersey and his colleagues studied two distinct time periods, 850–1800 and 1970–2005. Despite the dearth of historical data before 1850, the researchers were able to estimate sea-level rise by studying microbes called foraminifera in sediment samples taken from salt marshes along the New Jersey shore. Combining that data with climate modeling of hypothetical cyclones, they found that before 1800 the area that is now New York City would have experienced some flooding once every 500 years and Sandy-level flooding once every 3000 years. Now, however, mostly due to the increased sea level, some flooding is more likely to occur every 24 years, and extreme flooding every 130 years. Although the researchers only considered the New York area, they say the entire East Coast is likely to see more flooding.