Simulated Climate Response to Long-term Solar Geoengineering
Abstract
Many climate modeling studies have been conducted to explore various climate effects of solar geoengineering. However, most studies, including the GeoengineeringModel Intercomparison Project (GeoMIP), conducted geoengineering simulations for only several decades, and thus neglect feedbacks from the deep ocean dynamics. Given the long lifetime of anthropogenic CO2 and long-term climate commitment to CO2 emissions, there is a need to understand climate response to solar geoengineering over long terms. For example, The National Research Council's report on solar geoengineering wrote, "Because the GeoMIP simulations are of limited duration (under a century), the deep ocean does not have time to come into equilibrium with the climate forcing. These G1 (simulations in which solar irradiance is reduced uniformly to offset warming effect from 4 × CO2) and 4 × CO2 simulations therefore do not provide an indication of how the climate would evolve if the albedo modification was maintained for centuries, allowing the deep ocean to respond …". We used Hadley Center Climate model, HadCM3L, to perform a 1000-year idealized solar geoengineering simulation in which solar irradiance is uniformly reduced by 4% to approximately offset global mean warming resulting from an abrupt quadrupling of atmospheric CO2. We contrast this solar geoengineering simulation with the control preindustrial simulation and the 4×CO2 simulation. Our results show that during the 1000 year simulation period, modeled global climate, including temperature, hydrological cycle, sea ice, and ocean circulation of the high-CO2 simulation departs substantially from that of the control preindustrial simulation, whereas the climate of the geoengineering simulation remains much closer to that of the preindustrial state with little drift. In particular, solar geoeningeering simulation stabilizes large-scale ocean meridional circulation throughout the 1000-year period. We do not use the simulation results to argue that we should implement solar geoengineering for a long period. Instead, our simulations indicate that solar geoengineering, if implemented continuously, may be able to stabilize many aspects of CO2-induced climate change over long terms.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMGC33B1234C
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 1622 Earth system modeling;
- GLOBAL CHANGEDE: 1630 Impacts of global change;
- GLOBAL CHANGEDE: 6304 Benefit-cost analysis;
- POLICY SCIENCES