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Pleistocene atmospheric pCO2 variations
Measurements from Antarctic ice cores show that CO2 content in the atmosphere has varied regularly by almost 100 ppm in tandem with global climate change. Since the first discovery in the 1980s, this variation remains a mystery. We are investigating the cause of this variation by forcing a global biogeochemical ocean model with various biological and physical forcings. Also, we are focusing on the nature of the response of sediments (chemical and isotopic composition) to large CO2 changes in order to constrain possible explanations.
Postindustrial change in the natural carbon cycle of the ocean
Fossil fuel burning and land use changes since the Industrial Revolution have emitted significant amounts of CO2 to the atmosphere. Various estimates indicate that roughly half of the total emitted CO2 has remained in the atmosphere, while the oceans and terrestrial biosphere (trees and soils) have absorbed the rest. It is important to obtain an accurate and precise partitioning of this anthropogenic CO2, because future uptake depends on how much has been absorbed by the oceans and terrestrial biosphere until now. We are using a biogeochemical climate model to better quantify this uptake. We also analyze measurements to constrain our estimates.
Carbon cycling of Lake Superior
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. Currently available data-based estimates of carbon fluxes for Lake Superior are inconsistent: best estimates indicate carbon losses (e.g., respiration) exceed inputs (e.g., biological production) by a factor of 2 to 6. We are developing a phosphate-based lower trophic level food web model within the framework of a high resolution physical model to provide a consistent carbon budget of Lake Superior.
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. Recent developments have been geared particularly to address biological components of the global ocean carbon cycle. See more details and view movie
Long-Term Model Intercomparison Project (LTMIP)
We are participating with MESMO in LTMIP, an intercomparison of model results to examine the long-term uptake of anthropogenic carbon emissions. Experiments include historical and prescribed pulses of CO2 into the atmosphere to understand the extent of the subsequent neutralization. Access MESMO results
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