Simulation of Greenhouse-Gas-Induced Climate Change

Research Objectives

The objectives of our research are to simulate and understand past, present and potential future climates and chemical compositions of the atmosphere.

Computational Approach

We employ finite-difference methods to solve in space and time the equations governing the large-scale motion of the atmosphere and ocean in spherical coordinates on the rotating earth, with parameterizations for the unresolved subgrid-scale processes. We use the Cray C-90 computer.

Accomplishments

With our atmospheric general circulation/mixed-layer ocean (AGC/MLO) model and our global ice-sheet/asthenosphere model, we simulated the onset of the last glacial climate 115,000 years ago. We used our AGC model to simulate and understand the observed tropical intraseasonal oscillation.

We performed simulations with the AGC/MLO model for the present climate; the equilibrium climate resulting from a doubling of the CO₂ concentration (2 x CO₂); and the equilibrium climates induced by the direct radiative forcing caused by the emission of sulfur dioxide (SO₂) gas, which is converted to sulfate aerosol in the atmosphere. We have performed two simulations for the worldwide emission of SO₂ -- one for the present emission rate and another for ten times this rate (10 x SO₄) -- and seven simulations for regional 10 x SO₄ emissions -- one each for Europe, North Africa, Russia, China, North America, and the Southern Hemisphere, and the seventh for all regions other than Europe. Using our simple climate/ocean model, we calculated trajectories of future global-mean surface-air temperature changes for the Intergovernmental Panel on Climate Change (IPCC) business-as-usual scenario and for two scenarios that stabilize the CO₂ concentration at 550 ppmv. We continued to develop and test our stratospheric-tropospheric general circulation/photochemical model and our coupled atmosphere/ocean general circulation model.

We developed a new hybrid numerical scheme for the transport of chemical species. From the observational temperature record, we estimated the climate sensitivity and sulfate-aerosol radiative forcing. We collaboratively developed an adaptive strategy for abating climate change, calculated the expected economic cost of protection or abandonment against sea-level rise in the United States, and calculated country-specific market impacts of climate change.

Significance

Our studies will facilitate the determination of the economic and ecological impacts of anthropogenic influences on atmospheric composition and climate, thereby facilitating development of rational mitigation and adaptation policies thereto.

Publications

Schlesinger, M. E., and M. Y. Verbitsky. 1996. Simulation of glacial onset with a coupled atmospheric general circulation/mixed-layer ocean-ice-sheet/asthenosphere model. Palaeoclimates -- Data and Modelling, 2:179-201.

Wang, W., and M. E. Schlesinger. N. d. The dependence on convection parameterization of the tropical intraseasonal oscillation simulated by the UIUC 11-layer atmospheric GCM. J. Climate, submitted.

Schlesinger, M. E., N. G. Andronova, A. Ghanem, S. Malyshev, E. Rozanov, W. Wang, and F. Yang. N. d. Geographical scenarios of greenhouse-gas and anthropogenic-sulfate-aerosol induced climate changes. In preparation.

URL

http://crga.atmos.uiuc.edu/

Geographical distribution of the difference in surface-air temperature between two scenarios that stabilize the CO₂ concentration at 550 ppmv for the year 2087, when the difference between the WRE (Wigley, Richels, Edmonds) and IPCC annual global-mean surface-air temperature changes reaches its maximum for a CO₂-doubling temperature sensitivity of 2.5 degrees C.