PEI Research Center News

Carol Peters ・ High Meadows Environmental Institute

Center for BioComplexity (CBC)

Carla Staver and Simon Levin, working with South African researcher Sally Archibald, have published a series of papers in Ecology, Science and the Proceedings of the National Academy of Sciences, combining analyses of satellite imagery and other data with mathematical models to illuminate the potential for tropical and sub-tropical systems to flip between savannas and forests due to the role of fires. They explore the historical influence of humans in increasing fire frequency, and the future potential of climate change to alter the balance between savannas and forests. The topic of fire as a driver of vegetation patterns was also the focus of a CBC-sponsored workshop with lectures by noted South African ecologist William Bond and Princeton Emeritus Professor Henry Horn, along with Staver and Archibald.

Juan Bonachela (Levin lab postdoc), Michael Raghib (formerly at the CBC, now at Los Alamos National Laboratory), and Levin, in work published in PNAS, modeled the plasticity of marine organisms to adjust their nutrient uptake machinery in periods of nutrient deprivation. Such plasticity is crucial to the survival of these organisms, and to the maintenance of biodiversity, and incorporation of this effect into models of the dynamics of the oceans can substantially modify predictions.

Levin, Iain Couzin, assistant professor of ecology and evolutionary biology, and Naomi Leonard, professor of mechanical and aerospace engineering, also received support from the Army Research Office to continue their research on collective behavior in animal populations, with new postdoctoral fellow Emmanuel Schertzer. CBC also welcomes new postdoctoral fellows Erol Akcay and Malin Pinsky. Akcay, Levin, and Politics Professors Adam Meirowitz and Kris Ramsay are the recipients of a new NSF grant, “The Evolution of Incentives and Social Structure Under Imperfect Information.” Finally, we bid adieu to Guy Ziv, who left to take up a position as Scientific Development Lead for the Natural Capital Project at Stanford.

Carbon Mitigation Initiative (CMI)

The Carbon Mitigation Initiative (CMI) has expanded the scope of its core areas of research by awarding three new research projects this fall. David Medvigy and Lars Hedin will coordinate field- and modelbased assessments of the response and resilience of tropical ecosystems to global environmental change. Athanassios Panagiotopoulos, Pablo Debenedetti, and Jeroen Tromp will develop molecularbased computational tools for predicting the physical and chemical behavior of systems relevant to carbon capture and sequestration. Alexander Glaser and M.V. Ramana will focus on emerging nuclear technologies that emphasize small-scale solutions and will examine how nuclear power potentially fits into a modern low-carbon energy system — one that may be more decentralized than today’s system.

The three awards are for two years and total $400,000. The new projects were selected through a CMI-run universitywide competition that included a review of all submitted proposals by a faculty committee. “The latest internal CMI competition brought forth terrific proposals,” said Robert Socolow, professor of mechanical and aerospace engineering and co-director of CMI. “The three winning projects bring outstanding new senior and junior faculty under the CMI tent.” For additional information about the selected research projects, see full article on CMI website: pei_cer.php. Robert Socolow served on the committees of external reports “America’s Climate Choices” and “Direct Air Capture of CO2 with Chemicals,” both published in May 2011. On May 18, 2011, Francois Morel received the Einstein Chair Professorship from the Chinese Academy of Sciences.

The Cooperative Institute for Climate Science (CICS)

An interdisciplinary team of Princeton scientists including Mechanical and Aerospace Engineering (MAE) graduate student Lauren Padilla, CICS associate director Geoff Vallis, and MAE associate professor Clarence W. Rowley, addresses the impact of forcing uncertainty and internal variability on estimates of transient climate sensitivity (TCS) (the double CO2 response of globally averaged surface temperature on short time scales) in a recent study published in the Journal of Climate. Using methodology from control theory, they compute a range of probabilistic estimates of TCS while varying the underlying assumptions about the nature of forcing uncertainty and climate variability. Additionally, the authors calculate how quickly the uncertainty in TCS may be expected to diminish in the future as additional observations become available.

According to the authors, given their most plausible uncertainty assumptions, the fast response of global average surface temperature to CO2 doubling will be between 1.3-2.6K at 90% confidence. And this uncertainty range increases with increasing uncertainty in historical climate forcing and natural variability. They also find that uncertainty range may be reduced by approximately 45% given an additional 20 years of observations. However, the authors emphasize that due to the great thermal inertia of the ocean, their results are applicable only to the short to medium term climate response and not the equilibrium response to sustained CO2 increases.

An online release can be found here: 10.1175/2011JCLI3989.1