Climate variability involves strong interactions among these climate systems, and certain phenomena, such as El Niño, arise from the interaction that could not exist in the individual systems alone. The Climate Systems Interactions (CSI) group, led by Prof. J. David Neelin, develops theory and modeling aimed at understanding these interactions.  In studying these interactions, our group specializes in the application of hierarchical climate modeling: building a hierarchy of models of successively less complexity, until the phenomenon has been distilled down to it's essential elements. The more complex models aim to simulate the phenomena, while the simpler models allow theoretical understanding. Many climate research groups make some use of hierarchical modeling; a particular concern of this group is to practice it systematically and attempt to make the derivation of the simpler and intermediate complexity members of the hierarchy as clean as possible.

The Theoretical Climate Dynamics (TCD) group, led by Prof. Michael Ghil, studies climate dynamics on all time scales -- from intraseasonal, through interannual and interdecadal, to millenial -- using the methods of dynamical systems theory.  They apply these methods to observations, numerical models, and experiments concerning the climate system -- the atmosphere, ocean, bio- and cryosphere -- through collaboration with researchers in North America and on other continents.

The main goal of the Biogeochemistry Research Group, led by Prof. N. Gruber, is to gain a better understanding of the interactions between physical, chemical, and biological processes that control the distributions of these climatically improtant elemants and how they change through time.  To reach this goal they use a broad palatte of chemically and physically based methods, which range from model simulations, the imterpretation of numerous observational data to the application of very precise and accurate methods  to measure constituent and isotope concentrations.

Richard P. Turco is a founding director of the UCLA Institute of the Environment, and performs a variety of research including air quality assessment, cloud microphysics and aerosol research, remote sensing, and chemical modelling.