Rotch professor of atmospheric and environmental science Steven Wofsy studies the role of the Amazon rainforest in regional and global climate.
“The idea that changes to the Amazon will have global ramifications, I think that’s a very likely outcome. Something important will happen.” atmosphere and linking the forest to global atmospheric circulation. “The idea that changes to the Amazon will have global ramifications, I think that’s a very likely outcome,” Wofsy says. “What we couldn’t say is what that outcome will be, specifically. Something important will happen, but we don’t really know what.” Today, scientists concerned about the changing global climate are interested in forests like the Amazon for their role in sequestering or emitting carbon. Carbon is a key ingredient in the greenhouse gases carbon dioxide and methane. The buildup of those gases in the atmosphere from human fossil fuel burning is thought to be the major culprit in global climate change. The Amazon’s enormous size makes it a natural storehouse for carbon. Scientists know that carbon is a major element in the cellulose and lignin that make up the tissues in the forest’s riotous plant growth. Carbon dioxide is absorbed by the leaves and converted to carbohydrates during photosynthesis. Some of it is locked up in the plant’s woody tissues while a lesser amount is released again during the energy-producing process of respiration. 2
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The carbon held in trunks, branches, and roots is stored away from the atmosphere until the tree dies and decomposes. But the Amazon rainforest is being cut down at an alarming rate, largely for conversion to pasture and agricultural fields. Already, 17 percent has been clear cut or burned; some estimates project as much as 30 percent will be gone by mid-century. In addition to human-caused deforestation, there is potential for loss of the forest due to climate change: predictions suggest that the Amazon could see warmer,
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drier years, with more frequent and longer droughts. Scientists are concerned this will cause the forest to die off and be replaced by grasslands, fire-adapted woodlands, and savannah. If that happens, it will be bad news for the planet. The Amazon is thought to store 70 to 80 billion metric tons of carbon in plant biomass. If the forest is burned to create fields and pastures, or if it dries out, dies off and decomposes, a significant portion of that stored carbon will be released into the atmosphere, speeding climate change. The forest’s changes have therefore put scientists urgently to work on two simplesounding but complex questions: “What is the forest doing now?” and “What will happen to it in the future?” Wofsy and professor of organismic and evolutionary biology Paul Moorcroft are both hard at work on the problem. Wofsy, a member of the Harvard University Center for the Environment (HUCE) Steering Committee, is using instruments mounted on towers and flown on small planes to determine just what’s going on with the forest today. Moorcroft, a HUCE-affiliated faculty member, is using Wofsy’s measurements to help him build a new generation of computer models to predict what the Amazon will look like in the future. A forest unbalanced Though scientists understand photosynthesis and respiration, there is much they don’t know about how the forest handles
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The Rainmaker: In the Amazon, Gauging the Resilience of a Rainforest Harvard researchers monitor Brazil’s changing earth, wind and water.
22 Acting in Time: An Interview with David Ellwood The Dean of the Harvard Kennedy School discusses the interplay of policy making and climate change.
3 Letter from the Director 20 The EPA @ 40 A December conference celebrated the history of the EPA and mapped the challenges ahead.
25 HUCE Scholarships Create Summer Research Opportunities Four undergraduates reflect on their experiences as part of the annual HUCE Undergraduate Summer Research Program.