Global warming poses daunting challenges for Metro Boston
by Marjorie Howard

Engineers, said Paul Kirshen, director of the Tufts WaterSHED Center and research professor of civil and environmental engineering, are interested in extremes of climate so they can design for a peak rainfall or flooding.

The Antarctic ozone hole yawns at 26 million square miles—roughly the size of North America—in September 2001. Dark blue colors correspond to the thinnest ozone, while light blue, green and yellow pixels indicate progressively thicker ozone. © Greg Shirah, GSFC Scientific Visualization Studio

But what happens when the climate is changing? How should engineers plan for global warming?

While scientists have been studying the effect of climate change on agriculture, very little work has been done about the effect of global warming on urban areas. Kirshen is the principal investigator in a three-year study called CLIMB: Climate's Long-term Impacts on Metro Boston. The study is funded with a $900,000 grant from the U.S. Environmental Protection Agency and covers the area within I-495. The project was carried out by members of Tufts' Department of Civil and Environmental Engineering along with researchers at the University of Maryland and Boston University and the Metropolitan Area Planning Council, Boston's regional planning agency. In February the research team presented some of its findings at the annual meeting of the American Association for the Advancement of Science (AAAS), the world's largest general scientific society.

Kirshen, who is also the project manager, said the study is probably the most comprehensive look at an urban area in the world, with a major effort being made to quantify results. The study takes as a given that global warming is occurring, something politicians may be arguing about, but one that most scientists, he said, agree is already taking place.

Emissions staying power
"The question," he said, "is how severe the impact will be. That depends on how much greenhouse gas humans continue to emit. The United States is the world leader in emissions and the biggest laggard in correcting the problem."

Global warming is occurring because carbon dioxide and other pollutants, mainly from cars, power plants and other industrial sources that burn gasoline, coal and other fossil fuels, are collecting like a blanket in the atmosphere, trapping heat and resulting in higher temperatures. Kirshen said increased temperatures are changing the climate by affecting such phenomena as precipitation patterns. In addition, he said, polar icecaps are melting, which raises the sea level, and the oceans are expanding because they take up more volume when they get warmer.

"You can try to control emissions," said Kirshen, "but even if you do, it will not immediately stop the climate change. Some emissions have a lifetime of more than a century in the atmosphere. So even if we stopped it today, we would still have a problem. It's a long-term concern."

At the AAAS meeting in Denver, the CLIMB researchers reported on the impact of climate change on coastal flooding and health. Researchers are close to completing their work on water supply, water quality, energy, transportation and river flooding.

Paul Kirshen © Mark Morelli

CLIMB found that during the next century, damage to residential, commercial and industrial buildings in metropolitan Boston could exceed $20 billion, depending on how the region chooses to respond to rising sea levels and the associated increases in coastal flooding. In fact, costs could run as high as $94 billion if weather conditions turn out to be more severe than expected. Damage could be avoided or limited if adaptations are made that limit building in areas where there is greater potential for flooding, flood-proofing is increased and protective structures are established.

And the seas keep rising
"We're already seeing the effects," Kirshen said. "In the last century in Boston, the sea level has risen six inches because of global warming. Over the next 100 years, we may see an increase of two or three feet. This will cause a permanent loss of land in some places—both developed and undeveloped land."

Another devastating result, said Kirshen, would be the effect storms would have as a result of a higher sea level. Coastal storms that would not have caused much damage in the past will cause more damage because they will be coming in on higher water. A storm like the blizzard of 1978, which caused $550 million in damage in today's money, occurs once on the average of every 100 years. With climate change, similar storms could occur once on the average of every 10 years by 2050 or 2075.

David Gute, associate professor of civil and environmental engineering and a member of the research team, looked at the effects of global warming on health in the region. First, he and his colleagues examined records of mortality and temperature and found that when there is a prolonged period of days when the temperature climbs above 90 degrees, mortality patterns start to increase. For cold, the threshold was 28 degrees, though the effect of cold on mortality is less certain than for hot weather.

This true-color image, taken in May 2001 by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), shows a large, thick plume of aerosols blowing eastward over the North Atlantic. The plume is the regional haze produced by the industrial Northeast. The haze is composed of sulfates and organics that come from cars and power plants. © NASA/Goddard Space Flight Center

Extreme forecasts
"While we're going to see more hot days, we think the adaptation response of the region will continue to improve," Gute said, "meaning more people will have air conditioning, and municipalities are now more aware of the dangers of hot weather and make provisions for it by opening air-conditioned buildings during heat waves. So although we will see more hot days, we think the region isn't going to suffer increases in mortality."

The downside, he said, is that more air conditioning creates more air pollution, one of the causes of global warming. If the region continues to adapt and respond to extreme weather events, particularly on the heat-related side, it will draw more of a demand for power. Cold weather increases demand for home heating oil.

Gute also said that global warming will bring about more extreme weather in general, including ice, snow and rain storms. This year, which brought a hot summer and cold, snowy winter, is an example of the system turbulence which is envisioned for the first part of the 21st century, he said.

Kirshen said the hope is that the report will prompt policymakers to respond and show that global warming cannot be ignored. In addition, it is hoped that other cities will undertake similar research.

Other members of the civil and environmental engineering department who participated in the CLIMB study were Professors Lewis Edgers, Masoud Sanayei, Stephen Chapra, Wayne Chudyk and Richard Vogel. In addition, Nicholas Magliano, the environmental health and safety manager for the Department of Safety and Risk Management, also worked on the study.