2010 Sea Level Rise Forum & Community Meetings

More than 450 people participated in the "Boston Harbor Sea Level Rise Forum," held on Tuesday November 9, 2011, at the New England Aquarium IMAX Theatre, and on Wednesday November 10, 2011, at the John Joseph Moakley U.S. Courthouse. 

Highlights of the Forum included keynote addresses by Gina McCarthy, Assistant Administrator of the U.S. Environmental Protection Agency, Guy Nordenson of Princeton University, Dr. Ellen Douglas of UMass Boston and Dr. Paul Kirshen of the Battelle Institute. Participants viewed specially-prepared maps by Drs. Douglas and Kirshen and Chris Watson of UMass Boston showing the potential impacts of sea level rise and climate change on Boston Harbor and local neighborhoods.

Wednesday's event at the Moakely Courthouse opened with a greeting from the City of Boston by Jim Hunt, Chief, Environmental and Energy Services, City of Boston and also included a panel response session. Participants in the panel response were Tom Kinton, Executive Director, Massport, David Begelfer, CEO, NAIOP Massachusetts, Hubert Murray, Sustainable Initiatives Manager, Partners HealthCare, and Leo Robinson, Chelsea City Council President. The forum closed with a wrapup by Kairos Shen, Chief Planner, City of Boston.

Additionally, over 100 people participated in two community meetings on November 22, 2010 at Maverick Landing in East Boston and on November 29, 2010 at the Harbor Point Community Center in Dorchester. All four events included open mike sessions that allowed for insightful comments and questions from the public.

Materials from the Forum, provided below, include the maps showing potential sea level rise, and the slides from the presentations by Drs. Douglas and Kirshen.

The Boston Harbor Association thanks the Barr Foundation for their generous support of the Forum and community meetings. 

Boston Inner Harbor at High Tide plus 7.5 Feet of Sea Level Rise 

Sea Level Rise Maps - Boston Harbor and Vicinity

Average global temperatures have been rising since the mid-1800s. A large portion of this warming has been attributed to the emission of excess carbon dioxide into the atmosphere by fossil fuel burning and by land use change. Other greenhouse gases (GHG) from other sources also contribute. Sea level is affected by rising global temperatures through two mechanisms: the expansion of ocean water as it warms and the addition of water to the oceans by melting ice caps and glaciers. The most recent scientific research suggests that sea level could rise as much as 2.5 feet by mid-century (2050) and anywhere from 2.5 to over 6 feet by the end of the century (2100)1. The large range in these estimates is due, in part, to the fact that future global warming rates will depend on future GHG emission rates and we do not know how these emissions rates will change in the future. It depends greatly on whether or not we chose to reduce our reliance on fossil fuel-based energy. The range is also due to an imperfect understanding of the dynamics of sea level rise.

The maps show the possible flooding due to an extreme coastal flood event under different scenarios of future sea level rise. We first had to figure out how high the storm surge from an extreme coastal flooding event would be. We did this by analyzing the water level data collected at the tide gage in downtown Boston since 1920. We subtracted the normal daily tidal fluctuations (predicted by a NOAA tide model) from the measured water levels. The difference we assumed was due to storm surge, which is the additional water height that occurs when a storm hits the coast. We selected our extreme event of interest as the flooding event that has a 1% chance of occurring in any year, commonly know as the 100-year storm event. From our analysis of the tide gage data, we estimated that the storm surge height of this extreme event was approximately 5 feet.

The tidal range (low tide to high tide) in Boston is about 10 feet. When a storm hits the coast, how much flooding occurs is highly dependent on the tide height at the time the storm hits. For instance, if an extreme storm (5-foot storm surge) hits at low tide, there would be little or no flooding, since the total water height would be lower than the normal high tide. However, if that same storm hits at spring tide (the highest of high tides that typically occurs twice a month), then we would experience an additional 5 feet of water on TOP of spring tide. In order to evaluate the worst case scenario, we have assumed that an extreme coastal storm event occurs at spring tide, which means that the resulting flooding would be the most expansive. Our maps were created to assess the areas that could be flooding under such conditions. We have developed three maps, using two possible sea level rise scenarios (2.5 and 5 feet), with and without an extreme (5-foot) storm surge. Although we really don't know the timing of such scenarios (because of uncertainties in our estimates of future GHG emissions and in SLR dynamics), we offer rough timeframes as well:

• The high tide plus 2.5 ft map represents bi-monthly flooding at spring tide on top of 2.5 feet of sea level rise, which is either the lower end of projected sea level rise by the end of the century, or the higher end of projected sea level rise by mid-century.

• The high tide plus 5 feet map is similar to what we could experience with a 5-foot storm surge at spring high tide right now. Or, this map also represents bi-monthly flooding at spring tide on top of 5 feet of sea level rise, which is the higher end of projected sea level rise by the end of the century.

• The high tide plus 7.5 feet map represents the 5-foot storm surge on top of 2.5 feet of sea level rise, which is the lower end of projected sea level rise by the end of the century. 

These maps were created by Chris Watson and Ellen Douglas (UMass Boston) and Paul Kirshen (Battelle Institute). Funding for The Boston Harbor Association's Sea Level Rise Forum was generously provided by the Barr Foundation.

References:

1. Vermeer, M., & Rahmstorf, S. (2009). Global sea level linked to global temperature. Proceedings of the National Academy of Science, 106(51), 21461-21462.

2. Kirshen, P., Watson, C. J., Douglas, E., Gontz, A., Lee, J., & Tian, Y. (2008). Coastal Flooding in the Northeastern United States due to Climate Change. Mitigation and Adaptation Strategies for Global Change, 13(5-6), 437-451. 

Download the maps showing potential sea level rise in the Boston Harbor area.

Download the slides from the presentations by Drs. Douglas and Kirshen.

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