In an effort to explain the impending climate changes that will affect the Boston area as well as the world, Civil and Environmental Engineering Professor Paul Kirshen presented an array of possible consequences and warnings to a small audience last night.
Kirshen also serves as the Climate's Long-term Impacts on Metro Boston (CLIMB) project director and co-chair of Tufts' Water: Systems, Science, and Society graduate school program.
Over the next 100 years, the February CLIMB report said that New England will experience a three to five degree Celsius change in average temperature, a 25 percent increase in precipitation, a 0.6 to one meter increase in sea level, and an uncertain degree of increase in the frequency and intensity of hurricanes and Nor'easters.
"We are already starting to see these changes," Kirshen said. Researchers looked at a global map of precipitation increases over the past century, which showed some areas have had as much as a 50 percent increase.
A degree of uncertainty is always present in climatic change predictions, Kirshen said, using a projected change in the Mid-Atlantic region as an example.
By 2100, the stream flow - which is the difference between precipitation and evaporation - in different areas of this region could decrease by as much 12.5 percent and increase by as much as 37.5 percent.
According to Kirshen, this difficulty in predicting exactly what will happen as a result of climate change makes it very difficult to achieve policy change in the area of environmental conservation.
This is demonstrated by the fact that neither the city of Boston or the Environmental Protection Agency (EPA) responded to the results of the CLIMB Project that projected very severe possible consequences for the Boston area.
There is "nothing really we can do to stop climatic change in the next centuries, even if we stop [greenhouse emissions] now," Kirshen said. Therefore, Kirshen advocates preparing for the consequences of climate change now, before it is too late.
Over the last hundred years, the sea level in Boston has risen one foot due to global warming, which expands the volume of the ocean and melts ice which land has been resting on, Kirshen said. Based on the CLIMB project projections, over the next fifty years the sea level in Boston will rise at least another foot.
This will lead to greater risks of flooding in the Boston area, Kirshen said. Extreme storms like the Blizzard of 1978, which flooded portions of Boston, occur on average every 100 years. If the sea level rises another 0.3 meters, however, this type of damage "could occur on average every 10 years," Kirshen said.
By the year 2100, if no changes are made, an extreme storm could overflow the Charles River Dam and flood all of the Back Bay area. By that time, with no changes to flood proofing or sea walls, an estimated $20 billion dollars worth of damage would have been caused if the sea level rose at the moderate estimate of 0.6 meters.
According to Kirshen, climate change is caused mainly by the Greenhouse Effect - the build-up of various gases such as carbon dioxide, nitrous dioxide, and methane in the Earth's atmosphere.
These gases prevent a portion of the sun's energy from escaping back into space, trapping it in the Earth's atmosphere and raising the average temperature around the globe.
Energy from the sun is what drives the hydrologic cycle of evaporation, precipitation, and run off of water that is constantly occurring everywhere on the planet.
This is important, Kirshen said, because increasing amounts of the sun's energy being trapped in the atmosphere causes an increase in the rate of the hydrologic cycle, which will affect humans in a variety of ways Kirshen demonstrated will be difficult to predict.
Kirshen's presentation was held in the Crane Room of Paige Hall.
