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Cambridge Is Planning for Worst-Case Climate Scenario

Lechmere Canal Park in East Cambridge, Massachusetts

This week, many are looking to the United Nation’s COP21 climate summit in Paris with high hopes (and some with low expectations) for a binding treaty to reduce global greenhouse gas emissions. Some 3,400 miles across the Atlantic, the City of Cambridge is also hoping for a climate best-case scenario, but starting to prepare for the worst.

Cambridge just released a report on an in-depth climate change vulnerability assessment the city conducted. It outlines the near- and long-term risks the city faces from climate change impacts including extended periods of record-breaking heat and flooding from sea level rise and powerful rainstorms. City officials plan to use the report to inform future city planning, public health initiatives, emergency preparedness efforts and more.

“We’ve been working on climate change since 1999, but until recently were focused on reducing greenhouse gas,” says John Bolduc, City of Cambridge environmental planner. “A decade or so ago we realized that a certain amount of climate change was unavoidable. In the Boston area we were seeing maps of future flooding from storm surges and that was scaring a lot of people.”

The assessment team included staffers from the works, health and community development departments. They hired scientists to conduct climate modeling to show the worst-case scenarios of climate change impacts and did community outreach with residents and anchor institutions such as Harvard, MIT and major biotech companies.

Going into the assessment, they expected flooding from sea level rise to be the biggest threat to Cambridge (the city isn’t right on Boston Harbor, but it’s close and connected by the Charles River). Instead they found that Cambridge residents should be most worried about unprecedented heat waves and flooding from heavy rains and snow.

Right now, Cambridge has, on average, 11 days each year with temperatures above 90 degrees. Their models found that by 2030, they’ll have triple the number of days over 90. By 2070, the city could have three whole months a year of days over 90 degrees and a significant number of those would cross the 100-degree mark.

Sam Lipson, the health department’s director of environmental health, says that’s a huge cause for concern.

“Normal human physiological ability to deal with heat breaks down over time. People who are older or have chronic illness are at risk. Then there could be things that combine with a heat emergency that could make them significantly worse,” he explains. Lipson says, for example, there could be power loss that affects air conditioning and, in tall buildings, water might not get pumped through the system.

Though sea level rise proved to be less of a significant risk for Cambridge than expected, future flooding will be a problem. The report explains that, “As air temperatures rise, the atmosphere can hold more water, leading to more intense precipitation events. Over time such extreme events will become increasingly frequent.”

Currently about 13 percent of Cambridge is flood prone. The report projects that by 2030, when major storms occur they will flood 18 percent of the city. By 2070 that number increases to 24 percent.

“Climate change is kind of scrambling all of our assumptions of what our future conditions will be like,” says Bolduc. “Up until now the city has developed with the climate of the past in mind.”

As such, Cambridge’s stormwater infrastructure such as pipes, manholes, dams and the like just aren’t up to the task of intensified storms. Unfortunately, it would be extremely difficult and costly to bolster that infrastructure.

Cambridge plans to use the assessment in a number of ways. First and foremost it will inform a climate change preparedness and resilience plan they’re now working on. They are also starting to partner with other cities and regional agencies to work on regional mitigation plans. Lipson says public health wants to use the document to get people to think about how they need to personally prepare for climate change impacts.

Bolduc says Cambridge is hoping that illustrating the worst-case scenarios might help the city’s work reducing their carbon impact: “I think the study provides people a picture of why it’s important to reduce greenhouse gas emissions to become more sustainable. Cambridge has a plan to be net zero on emissions by mid-century. We need to continue working towards that.”

Of course Bolduc and his colleagues recognize that climate change is a global issue that will require global action. But, he sees small cities like his as a critical part of the climate solution.

“Climate change is such an overwhelming issue especially when you think of it on a global scale,” says Bolduc. “Looking at things on city scale makes them more digestible and manageable. Plus city governments compared to other levels are more nimble about policy. We can be a laboratory for dealing with climate change.”