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The science behind the politics of climate change

In December as thousands of world leaders, scientists and advocates gathered in Copenhagen for the United Nations’ Climate Change Conference, two Falmouth Academy alumni on both sides of the Atlantic Ocean were putting their own stamp on the science of climate change policy. Tim Cronin ’02 is conducting modeling to determine the usefulness of second-generation biofuels, and Zoli Szuts ’97 is monitoring climate change effects on ocean circulation.

Modeling second-generation biofuel usefulness

Tim Cronin ’02, a presidential fellow and first-year Ph.D. student in MIT’s Atmospheres, Oceans and Climate program, worked with Dr. Jerry Melillo, senior scientist and former co-director of the Ecosystems Center at the Marine Biological Laboratory (MBL), and his research team for three years, devising ways to model the effects of environmental changes, including climate change, on land ecosystems such as forests, savannahs and grasslands.

No stranger to concocting “what ifs,” Cronin graduated from Swarthmore College with a degree in physics, and is the veteran of many science fair award podiums, having earned third, second and first place awards in successive years at the Massachusetts State Science Fair. His projects ran the gamut from testing the flow rates of Karo syrup, determining the mid-life prime of trees by analyzing their growth rings, and improving the aerodynamics of pick-up trucks by testing their drag coefficients in a wind tunnel that he built.

“Falmouth Academy had an influence on what I do now,” said Cronin. “I find myself doing stuff that I did at FA, which, of course, has gone through several mutations. My class on the fluid dynamics of atmosphere and oceans reminds me of my 8th grade Science Fair project. I was definitely influenced by Peter Conzett in my earth science and physics classes there.”

Cronin joined MBL as a research assistant following his graduation from Swarthmore. He worked on the Terrestrial Ecosystems Model, which is used to simulate how simultaneous changes in environmental factors, such as climate, atmospheric carbon dioxide concentration, acid rain and near-surface ozone, affect land ecosystems – their productivity, carbon storage capacity, ability to purify water, and so on. He gathered information on ways to improve the mathematical equations in the model that describes these effects.

“Tim made fundamental contributions and improvements to our approach to modeling terrestrial ecosystems,” said Melillo.

In recognition of his contributions, Cronin is listed as co-author of several papers that have appeared in prestigious peer-reviewed scientific journals. The latest, a joint effort between MBL and MIT researchers, “Indirect Emissions from Biofuels: How Important?” was published in /Sciencexpress in October, as well as in the December 4 issue of its parent publication, Science.

When the MIT-MBL research team asked what the world would look like if second-generation biofuels met a significant percentage of the world’s energy needs, Cronin became actively involved in devising modeling approaches and scenarios for a version of the Terrestrial Ecosystem Model that was coupled with a global economic model developed at MIT. Second-generation biofuels, those produced by transforming plant cellulose into liquid fuels such as ethanol, have been proposed as a substitute for gasoline as scientists seek ways to reduce dependence on fossil fuels and slow climate change.

“I did a lot of the go-between work with the two research groups,” said Cronin. “I helped to come up with some of the ways to present our results that ultimately worked well. I also did miscellaneous things like making maps and writing parts of the supplemental materials for publication.”

Melillo praised Cronin for his work. “Because he is a ‘big-picture’ person and extraordinarily clever, Tim had significant input to this project.”

The results of their work provide a framework for influencing global policies.

For example, the study reported in Science was the result of modeling and predicting where in the world it would be most economical to grow second-generation biofuels in order to meet a significant percentage of the world’s energy needs, and how such use of land, both directly and indirectly, would impact the world’s ecosystems and feed back to the climate system.

Melillo said, “Not surprisingly, our coupled ecosystem and economic model identified the tropical regions of the world as the most likely places to grow the plants needed to produce the biofuels. In many parts of the tropics, the growing seasons are long and land and labor are cheap.”

In the Science article, the international team of scientists, including Cronin, noted that an aggressive global biofuels program that is primarily based in the tropics will lead to intense pressure on land supply (land to grow food crops versus land to grow biofuels crops) and can increase greenhouse gas emissions from land-use changes. Their work raises important questions for policy makers who are thinking through various strategies for meeting the challenge of climate change.

By linking the inputs and outputs of the MBL and MIT models, the team attempted to discover what would happen if this energy supply path was followed.

Cronin said, “What we tried to do more than tweak equations is tweak inputs and outputs. By using the output of the economic model (i.e. land-use shares for crops, biofuels and pastures) as an input to the ecosystem model, we could get a sense for how the carbon uptake by the biosphere changes due to these economically-driven land-use changes. By using the output of the ecosystems model (i.e. changing productivity of land due to climate changes and other factors like ozone pollution) as an input to the economics model, we can try to get a sense for how much more (or less) land is required to grow food crops or biofuels, due to the impacts of environmental change on agricultural productivity.”

Cronin has four more years to go in his Ph.D. program. He said someday he could imagine teaching at a college, but has nothing particular in mind right now. “I think it would be nice to maintain my friendships with people who are doing interesting things and, as we all move up, it would be nice to engage in policy-relevant ways.”

Monitoring climate change effects on the ocean

Zoli Szuts ’97, a postdoc researcher at the Max Planck Institute for Meteorology in Germany, is monitoring the state of ocean water circulation around the globe to determine how quickly climate change will alter circulation, the “climate” of the ocean.

Recently returned from a cruise across the Atlantic Ocean, which began off the coast of West Africa in Santa Cruz de Tenerife and ended at Great Abaco Island in the Bahamas, Szuts recovered and analyzed data from instruments deployed along 26.5 degrees North in the Atlantic.

Ocean water circulates the globe in a continuous stream in which warm salty water on the surface flows to polar seas, cools enough to sink to the bottom of the ocean, and then flows backward to return to its source. This is called the “ocean conveyor belt.” The Gulf Stream is a part of this global circulation in the North Atlantic and is largely responsible for the mild climate of England and northern Europe.

Szuts and his team calculated the volume of northward and southward flowing water from measurements taken on either boundary of the Atlantic at 26 N. Satellite observations of winds and independent measurements of the strength of the Gulf Stream as it flows past Florida are also required for calculating the net volume of water flowing through 26 N.

One of his interests is the design and use of instruments for making physical oceanography observations, specifically as part of the British-based project RAPID that monitors the Atlantic Meridional Overturning Circulation (MOC). “I am responsible for making sure that the data are high quality and scientifically meaningful.”

Szuts’ project has been observing the MOC for only 4.5 years, so the measurements are not yet long enough to determine a trend. However, continued data collection will produce valuable baseline data for measuring future changes, in addition to a better understanding of changes seen over periods of a week to a year.

What Szuts finds particularly interesting is that although it is relatively straightforward to make the calculations, understanding what the signals mean is far from obvious. “There is much debate about whether the overturning circulation (and by extension, the Gulf Stream) will increase or decrease as the earth’s climate changes.”

He said that most of our conceptual understanding of oceanography has been developed in the center of the ocean where the sides of the ocean don’t add any complexities. In contrast the overturning circulation is defined from one side of the ocean to the other and the signal is very different if instruments are moved even 20 kilometers off of the boundary.

“So, aside from providing a baseline for future climate change, our measurements will push our conceptual understanding of what drives global ocean circulation.”

Szuts began his career at Oberlin College, where he majored in biology. He then received his Ph.D. in oceanography in 2008 at the University of Washington, where he investigated the technique that allows the transport of the Gulf Stream between Florida and the Bahamas to be measured. This measurement is one of the components essential for calculating the Atlantic MOC.

Two years into his college career, Szuts did a Semester at SEA (Sea Education Association) cruise, a prize he had won for a Falmouth Academy Science Fair physics project. This cruise and a summer program in the Woods Hole Oceanographic Institution’s research Experience for Undergraduates program set the stage for him to shift interests to oceanography.

Today, his colleagues work with global circulation models that couple the atmosphere and the ocean. Szuts said these models are predominantly used for examining decadal, centennial and millennial scale climatic signals. “Their model was one of the 20 or so included in the IPCC (International Program on Climate Change) 4th Assessment Report that won the Nobel Peace Prize along with Al Gore.”

In addition to his current project, last summer he attended two high-level conferences in Taiwan and Venice: a planning workshop for measuring water flowing through the Indonesian Archipelago, and planning the next ten years of oceanographic measurements.

For more information on Szuts’ project, visit the Web site: http:/www.noc.soton.ac.uk/rapidmoc/home.html