CMI Science focuses on how terrestrial vegetation and the oceans soak up carbon and thereby determine the fraction of the carbon dioxide (CO2) emitted into the atmosphere that actually stays there (the fraction is about one-half). CMI science increasingly features close collaboration with Princeton’s neighbor, the Geophysical Fluid Dynamics Laboratory (GFDL) of the US Department of Commerce. A recent and growing component of CMI addresses climate variability and departures from the historical frequency of extreme events, such as heat waves, droughts, and hurricanes.
Research Highlights – At a Glance
Stephen Pacala: Tropical forests represent a key terrestrial carbon sink, yet their levels of carbon storage have been challenging to estimate due to the multi-layered structure of tropical forest tree communities. The Pacala group has used data from Panama’s Barrow Colorado Island Rainforest to develop a model for investigating carbon storage in tropical forests with improved accuracy. Another challenge is understanding methane emissions from oil and gas infrastructure, due to the ephemeral nature of high-emitting sources. The Pacala group has created a new method for estimating methane emissions that combines systematic and biased sampling data with meteorological factors.
Jorge Sarmiento: Biological and geological processes occurring in the Southern Ocean around Antarctica have important impacts on global carbon and climate cycles. Recent modeling results show that the Southern Ocean acts as a key sink for atmospheric CO2, thus mitigating global temperature increases caused by rising levels of CO2. To examine the dynamics of these processes across space and time, Jorge Sarmiento is directing the world’s first large-scale deployment of robotic floats equipped with biogeochemical measurement instruments. The project will enable unprecedented observations of pH, biological productivity, carbon cycling, and phytoplankton dynamics in the Southern Ocean.
François Morel: Increasing concentrations of atmospheric CO2 lead to higher concentrations of dissolved CO2 in surface seawater. This results in ocean acidification, which may affect the growth of the photosynthetic phytoplankton that form the basis of marine food webs. The Morel group has conducted both field and laboratory experiments to examine the effects of acidification on phytoplankton productivity. The results will enable future assessments and predictions of how CO2 concentration changes impact marine ecosystems.
Michael Bender: Studies of ice cores from Greenland show that the Greenland ice sheet has persisted for at least 1 million years. This result puts limits on the sensitivity of the Greenland ice sheet to climate change, and provides a test for models of the ice sheet.
Stephen Pacala and Elena Shevliakova: Beyond assessing effects of greenhouse gas emissions on trends in global temperature increases, research efforts led by Pacala and Shevliakova have advanced analysis of extreme precipitation from observations and climate model simulations, as well as improved representation of processes that affect climate extremes on regional scales, such as urbanization and dust emissions.
Current Research Projects
- Modeling Tropical Forest Carbon Storage and Estimating Methane Emissions
- Update on the Southern Ocean Carbon and Climate Observations and Modeling Project
- The Greenland Ice Sheet, a Million-Year Record of Climate Change and Sea Level Rise
- Effects of Ocean Acidification on Marine Phytoplankton
- Climate Variability and Changes in Future Extremes
- Science Publications