HR: 15:25h
AN: OS12B-07    [PDF]
TI: The Sensitivity of Ocean Circulation and Carbon Uptake to the Rate of CO2 Increase and the Resultant Changes in Climate and Hydrological Cycle
AU: * Cao, L
EM: longcao@atmos.uiuc.edu
AF: University of Illinois, department of atmospheric science, 105 S. Gregory Street, Urbana, IL 61801 United States
AU: Jain, A K
EM: jain@atmos.uiuc.edu
AF: University of Illinois, department of atmospheric science, 105 S. Gregory Street, Urbana, IL 61801 United States
AB: We investigate an important feedback loop in the climate-carbon cycle system that involves increase in atmospheric CO2 and the resulting changes in temperature, the hydrological cycle, ocean circulation, and oceanic carbon uptake. This study is conducted using the coupled atmosphere-ocean-carbon cycle component of the Integrated Science Assessment Model (ISAM). The coupled model includes an energy-moisture balance atmosphere module, a thermodynamic sea-ice module, and a zonal mean ocean module. The ocean component resolves major ocean basins and is based on the balance equations of momentum, temperature, salinity and carbon and its isotopes. The coupled model has the ability to successfully simulate historical and current climates, the ocean thermohaline circulation (THC), oceanic carbon uptake, and bomb 14C. Global warming may cause a weakening or even a collapse of the THC through the increased sea surface temperature and an enhanced hydrological cycle, which can reduce oceanic carbon uptake, thus accelerate the global warming. Recent studies find that the change in the THC is dependent not only on the concentration of atmospheric CO2, but also on the rate of CO2 increase. Using a variety of CO2 increase scenarios (e.g., 0.5%, 1%, 2%/yr CO2 increase from present concentration to the level of doubling or quadrupling of CO2), we extend previous studies by assessing the effect of the rate of CO2 increase, temperature, and hydrological cycle not only on the THC but also on the oceanic carbon uptake. We also explore the threshold values of the rate of CO2 increase and the absolute amount of atmospheric CO2 that are likely to induce the collapse of the North Atlantic Deep Water (NADW) formation, which can have dramatic effects on oceanic uptake of CO2.
DE: 1803 Anthropogenic effects
DE: 4203 Analytical modeling
DE: 4255 Numerical modeling
DE: 4504 Air/sea interactions (0312)
DE: 4806 Carbon cycling
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting