His work focuses on the Earth's response to external and internal forcings that have time scales ranging from seconds to billions of years. He has written extensively on topics ranging from the connection of mantle convective flow to the geological record, the rotational stability of the Earth and other terrestrial planets, ice age geodynamics, and the geodetic and geophysical signatures of ice sheet melting in our progressively warming world. Sea-level change has served as the major theme of these studies, with particular emphasis on critical events in ice age climate and on the sea-level fingerprints of modern polar ice sheet collapse.