Raymond Pierrehumbert

Senior Fellow


At present, my central interest is in how climate works as a system. I wish to develop idealized mathematical models that can be used to address the big questions of climate science: How did the earth keep from freezing over during the Faint Young sun period in its history? Why did Earth keep its water while Venus got trapped in a runaway greenhouse? What possible past climates could exist on Mars? Why was the Eocene so warm on Earth? What was tropical sea surface temperature doing during the Last Glacial Maximum? This involves work at the interface of fluid dynamics and radiative transfer. My philosophy is to approach this using simplified models (albeit often ones involving some degree of computation) that can be understood completely, rather than full-blown General Circulation Models. A recurrent theme in much of this work is the determination of the Earth's relative humidity distribution, which is the key to many climate change problems.

Although I consider myself primarily a theoretician, modern network and computer facilities make data readily accessible, and I try to provide my students easy access to a variety of data sets and computational resources. We have links to the broader observational and modelling community through a number of collaborative efforts.

I have also maintained an interest in more traditional areas of geophysical fluid dynamics, particularly as related to baroclinic instability, storm track structure, and planetary wave propagation. I am also actively engaged in fluid mechanical research of a more abstract nature, particularly as related to two-dimensional turbulence and mixing in two-dimensional area-preserving flows. In this work there has proved to be good cross-fertilization with ideas generated in active nonlinear research groups in Physics and Astrophysics.