He is a fellow of the Royal Society of Canada, of the American Geophysical Union, of the American Meteorological Society, and of the Norwegian Academy of Science and Letters.. His research interests include: atmospheric and oceanic waves and turbulence, geophysical fluid dynamics, physics of the planetary interior, and planetary climate.
His gravitationally self-consistent global theory of Ice-Earth-Ocean interactions has become widely employed internationally in the explanation of the changes of sea level that accompany both the growth and decay of grounded ice on the continents, both during the Late Quaternary era of Earth history and under modern global warming conditions.
His models of the space-time variations of continental ice cover since the last maximum of glaciation are employed universally to provide the boundary conditions needed to enable modern coupled climate models to be employed to reconstruct past climate conditions.
A most notable contribution to work of this kind has been his theory of the so-called Dansgaard-Oeschger millennial timescale oscillation of glacial climate.
These models are important for the quantification of post-glacial rebound and late Pleistocene to Holocene variations in sea level.