A central theme of my research is the identification of the conditions that maintain the habitability of a planet (including our own Earth), and understanding the robustness or otherwise of these conditions in the face of environmental perturbations ranging from evolutionary innovations or asteroid impacts, to the global warming occasioned by human-caused disruption of the carbon cycle. I maintain research programs concerned with the Early Earth climate, notably the enigmatic extreme glacial climates of the Proterozoic, as well as climates of Venus, Mars and Titan and hypothetical climates of the newly discovered exoplanets. Nearer to home, I am conducting research related to human-caused global change on the century to millennium scale, and especially the nature of the Anthropocene. This work includes such topics as the comparison of climate effects of methane abatement vs carbon dioxide abatement, and the effect of agricultural production on climate. Although I employ complex general circulation models when required, the bulk of my work involves construction of small idealized models based on fundamental principles of radiative transfer, thermodynamics and fluid dynamics. Although I am receptive to advising DTP students across the full spectrum of my research interests, the two particular subjects I am particularly interested in pursuing are: (1) Development of the use of idealized models of oceanic heat and carbon uptake which go beyond the diffusive models currently in use, and exploring their implications for the Cumulative Carbon concept, and (2) Examining the implications of various possible behaviors of the terrestrial carbon cycle for the connection between cumulative carbon emissions and climate.