Research

Pleistocene climate and carbon cycle variations
Measurements from Antarctic ice cores show that CO2 content in the atmosphere has varied by almost 100 ppm in tandem with glacial-interglacial global climate change.  Since the first discovery in the 1980s, this variation remains a mystery and is a target of our investigation. We are also interested in understanding the variations in ocean biogeochemistry and circulation, radiocarbon distribution, deep sea sedimentation, and land vegetation. These variations occur over glacial-interglacial time scale and during shorter, rapid climate change events. Our main tool of investigation is MESMO, an earth system model of intermediate complexity (see below).

 

Postindustrial climate and carbon cycle chanages
Fossil fuel burning and land use changes since the Industrial Revolution continue to emit a significant amount of CO2 into the atmosphere. This anthropogenic CO2 leads to global warming and ocean acidification. The severity of these environmental problems depends in part on the partitioning of the emitted CO2 between the major carbon reservoirs: the atmosphere, the world ocean, and terrestrial biosphere (trees and soils).  Using models and data analysis, we are attempting to quantify this partitioning and how it impacts the sensitivity of global climate change and ocean acidification.

 

Lake Superior's thermal bar, carbon, and ecosystem
Lake Superior is the largest lake in the world by surface area and contains about 10% of all surficial freshwaters.  It is minimally disturbed by development as compared to the other Laurentian Great Lakes. There is much that is poorly understood about the lake. We are interested in understanding its thermal evolution (e.g., the thermal bar), lake ice, carbon cycle, and ecosystem. To this end, we have recently developed a realistically configured, 3-dimensional physical model of Lake Superior based on the ROMS architecture. It includes a dynamic-thermodynamic model of ice and phosphate-based lower trophic level food web. At the same time, we are examing satellite data to gain observational constraints.

 

MESMO: Minnesota Earth System Model for Ocean biogeochemistry
The Minnesota Earth System Model for Ocean biogeochemistry (MESMO) is model of intermediate complexity based on the Grid ENabled Integrated Earth system model (GENIE-1). It is comprised of a 3D dynamical ocean, energy-moisture balance atmosphere, dynamic and thermodynamic sea ice, and marine biogeochemistry. The reduced spatial resolution renders it both computationally efficient while still retaining important dynamics. In MESMO2, a model of terrestrial biosphere is coupled, and ocean biogeochemistry has been extended to include iron and diatom growth with variable Si/N uptake rate. See more details and view movie