Grants and Contributions:

Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023)

The research program is comprised of several linked components that address issues involving understanding climate-critical interactions that occur within the solid Earth and its atmosphere and oceans. Central components of the proposed research include (1) continuing development and application of the theory of Ice-Earth-Ocean interactions that describes the processes of glacial isostatic adjustment and relative sea level change. This unique contribution to the field will continue to lead to improved understanding of both the effective viscosity of the Deep Earth and of surface glaciation history, the latter required for model based reconstruction of past climates; (2) intensification of the work on the origins and nature of density stratified turbulence, work that has already led to significant advances in understanding the turbulent diffusion of mass that occurs in the global oceans. Since this diffusivity plays an important role in the mechanism whereby cold and salty (dense) water that descends to great depth at high latitudes is able to return to the surface, it is crucial to understanding the climatologically important thermohaline circulation. Proposed extensions of this work will focus upon the development of explicit models of the turbulence produced by tidally forced internal wave breaking under both modern and past conditions; (3) work on the further development of the theory of ice-age climate variability, as in the recent identification of the mechanism responsible for the previously unexplained millennium timescale Dansgaard-Oeschger oscillations that dominated climate variability between 60,000 and 30,000 years ago. These constitute an important example of the fact that climate change may occur extremely rapidly. In the next grant period this work will be extended to include complete glacial-interglacial integrations of the coupled climate system to resolve the entire sequence of rapid events that occurred between 21,000 and 10,000 years ago using boundary conditions provided by work under component (1); and (4) work directed towards understanding regional aspects of the global warming process and of the transition into this so-called Anthropocene period from the preceding millennium. Detailed regional analyses of the earlier transition from the medieval warm period into the little ice age have been produced and will be further refined using the highest resolution modern climate models available. This component of the program will also involve the application of dynamical downscaling techniques to the understanding of Anthropocene warming impacts at the regional scale that are important for the development of science based environmental policy. In this area recently published work on both the Great Lakes Basin of North America and on Western Canada will be extended to include Greenland, as well as Southeast Asia and the Tibetan Plateau.