We study the interactions between climate change and biogeochemical cycles, and focus on the processes that maintain and alter the composition of the atmosphere, and hence the climate.
A question driving my research is how will atmospheric CO2 and climate co-evolve, and what we can do about it. We continue to analyze atmospheric, land and ocean observations pertinent to the carbon cycle, and to synthesize them in atmospheric transport models to infer how CO2 sources and sinks have been changing. We are also using the coupled carbon-climate model at NCAR to project how land and ocean carbon sinks will change with accelerating global warming and with human activities. A not surprising finding is that the droughts have diminished, and will continue to diminish, the land uptake of CO2.
Our group has taken several approaches towards the hydrologic cycle. We have incorporated water isotopes into the NCAR atmospheric general circulation model to diagnose the water cycle. Dust links the carbon cycle and the hydrologic cycle, as dust arises from (certain) arid regions, their deposition to the ocean stimulates marine productivity (at least for 1-2 weeks), and they reflect and absorb radiation. To understand the life cycle of water itself and how plants both respond to and change the water in the soils, we have embarked on a new and exciting project – the HydroWatch Project – to monitor and model water in the atmosphere, trees, soils, rock fractures and streams. Our first deployment (in October 2007) was at the Eel River at the Angelo Coast Reserve, one of the UC Natural Reserves.
A new satellite, the Orbiting Carbon Observatory (OCO) is scheduled for launch in late 2008. OCO will collect an unprecedented volume of data on the CO2 mixing ratio in the atmospheric column. In collaboration with Eugenia Kalnay (U. Maryland), we plan to assimilate the OCO data in conjunction with meteorological observations into the global carbon-climate model. The goal is to use OCO data to constrain estimates about processes that exchange CO2 between the atmosphere and the surface (land and oceans).