Comparing transient, accelerated, and equilibrium simulations of the last 30 000 years with the GENIE-1 model

• Main Authors: Lunt, D. J., Williamson, M. S., Valdes, P. J., Lenton, T. M.
• Other Authors: Bristol Research Initiative for the Dynamic Global Environment (BRIDGE), School of Geographical Sciences Bristol, University of Bristol Bristol -University of Bristol Bristol, School of Environmental Sciences Norwich, University of East Anglia Norwich (UEA), Tyndall Centre for Climate Change Research, Current affiliation: Quantum Information Group
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2006
• Subjects: [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Southern Ocean; ice core; Ice Sheet; Sea ice
• Online Access: https://hal.science/hal-00298130; https://hal.science/hal-00298130/document; https://hal.science/hal-00298130/file/cpd-2-267-2006.pdf

International audience We examine several aspects of the ocean-atmosphere system over the last 30 000 years, by carrying out simulations with prescribed ice-sheets, atmospheric CO 2 concentration, and orbital parameters. We use the GENIE-1 model with a geostrophic ocean, dynamic sea-ice, an energy balance atmosphere, and a land-surface scheme with fixed vegetation. A transient simulation, with boundary conditions derived from ice-core records and ice-sheet reconstructions, is compared with equilibrium snapshot simulations, including the Last Glacial Maximum (21 000 years before present; 21 kyrBP), mid-Holocene (6 kyrBP) and pre-industrial. The equilibrium snapshot surface temperatures are all very similar to their corresponding time period in the transient simulation, suggesting that in the last 30 000 years, the ocean-atmosphere system has been close to equilibrium with its boundary conditions. We investigate the method of accelerating the boundary conditions of a transient simulation and find that the Southern Ocean is the region most affected by the acceleration. The Northern Hemisphere, even with a factor of 10 acceleration, is relatively unaffected.