Will Boston experience serious flooding and become as vulnerable as New Orleans? Evidence from the Boston Harbor tide gauge (located near the Congress Street Bridge) suggests that there may be trouble ahead.
The sea level measured at Boston Harbor has risen about a foot (25 centimeters) since records began in 1921. One effect of global warming is to expand the volume of water in the oceans. The increased melting of glaciers and polar ice caps adds to this trend.
A comparison of the top ten water levels measured by the Boston tide gauge makes startling reading. All but one of the highest recorded levels occurred during the last forty years. By contrast, the first fifty-two years of data showed relatively unremarkable high tides.
Dates of Boston’s top ten sea levels since 1921, in descending order, are as follows:
- Feb. 7, 1978
- Jan. 2, 1987
- Oct. 30, 1991
- Jan. 28, 1979
- Dec. 12, 1992
- Dec. 12, 1959
- Feb. 2, 1972
- April 4, 2007
- May 5, 2005
- Dec. 12, 2010
As expected, the high points cluster around the traditional winter storm season, with 60% of the record events occurring between December and February.
Surprisingly, neither the dates of Hurricane Sandy nor Storm Nemo are listed on the top ten list, since both storms reached their peak at or close to low tide. A similar event at another time of the day would have much more devastating consequences.
Science writer Andrew Freedman notes that the long-term rise in Atlantic sea levels will result in an increased risk of coastal storm surges affecting New England. In his most optimistic estimate, major coastal flooding events (of the type previously experienced every 10 years) are likely to take place in the northeast every three years by 2100.
Less optimistically, by 2030, the number of 1-in-100-year storm surges is predicted to double. This type of flood – five feet above the current average high tide – would result in about 6% of the city of Boston being flooded. A rare surge seven-and-a-half feet higher than average would result in 30% of Boston being swamped by incoming sea and rain water. By way of comparison, Hurricane Katrina flooded 85% of New Orleans, and claimed over 1,000 lives.
The future looks challenging for the Northeast, but active citizens are already aware of the responses needed to try and mitigate these risks. As the non-profit Boston Harbor Association explains in its recent report Preparing for the Rising Tide:
“Although Boston is recognized as one of the country’s more climate-aware cities, more work is needed to prepare this historic city for current and future risks of coastal flooding…. Increasing Boston’s resilience to coastal flooding will take a strong public-private partnership that optimizes the resources and expertise of all sectors.”
Any Northeast residents out there? How do you see your future in climate terms?