Brookhaven Lecture

Plants exchange huge quantities of carbon dioxide and water vapor with the atmosphere. Understanding and modeling these exchanges is key to projecting the response of plants and ecosystems to climate change, and is essential for reducing uncertainty in projections of future global change. Annually, plants take up about ten-times more carbon dioxide than we emit when we use of fossil fuels. Plants also absorb about one-third of the carbon dioxide released from combustion of fossil fuels. Therefore, uptake of carbon dioxide by photosynthesis is not only the largest flux of carbon dioxide on the planet, but also the gatekeeper process for the uncertain terrestrial carbon sink that currently subsidizes our use of fossil fuels. Many of the observed and projected impacts of global change portend increasing environmental and economic risk, yet the uncertainty surrounding the projection of our future climate remains unacceptably high. Model representation of the exchange and carbon dioxide and water vapor by plants has been shown to dominate uncertainty in key model outputs. Therefore, increasing confidence in model representation of photosynthesis is an essential part of reducing overall uncertainty in projections of global change. Focusing on leaf level physiology, Dr. Rogers will discuss how plants and photosynthesis are represented in climate models, and highlight how uncertainty in parameterization and process representation in climate models is being challenged by data from field work conducted in the Arctic and tropics.