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Modeled changes to the earth’s climate under a simple geoengineering scheme and following geoengineering failure

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dc.contributor.author Shumlich, Michael John
dc.date.accessioned 2012-09-21T22:42:32Z
dc.date.available 2012-09-21T22:42:32Z
dc.date.copyright 2012 en_US
dc.date.issued 2012-09-21
dc.identifier.uri http://hdl.handle.net/1828/4290
dc.description.abstract Geoengineering is the intentional alteration of the Earth’s climate system. The international Geoengineering Model Intercomparison Project (GeoMIP) seeks to identify the potential benefits and side effects of geoengineering on the Earth's climate. This thesis examines the first two experiments from the contribution of the Canadian Centre for Climate Modelling and Analysis to GeoMIP. In the first experiment (G1), atmospheric carbon dioxide concentrations are quadrupled and the solar constant is reduced to offset the increased greenhouse gas forcing. In the second experiment (G2), atmospheric carbon dioxide concentrations are increased at the rate of 1% per year and the solar constant is incrementally reduced to offset the greenhouse gas forcing. In concert with these experiments, results from two other experiments were analyzed, one in which the atmospheric greenhouse gas concentrations are quadrupled one in which they are increased at the rate of 1% per. The results obtained are in broad agreement with earlier work, showing that solar radiation management geoengineering schemes can prevent an increase in mean global surface temperature as atmospheric carbon dioxide concentrations increase. Though the mean global temperature remains constant while geoengineering is employed, there are regional and zonal differences from the control climate, with high latitude warming and cooling in the tropical and subtropical regions. In particular, the meridional temperature gradient is reduced compared to that of the control climate. The G2 experiment was very similar to the G1 experiment in terms of the spatial surface temperature changes, though the changes seen in the G2 experiment were less pronounced and the regions of statistical significance were smaller. During the geoengineering period, seasonal changes and a statistically significant decrease in global precipitation, particularly over the ocean were apparent in the G1 run. As with temperature, the spatial pattern of precipitation changes during the geoengineering period for G2 are similar to the same period in G1, but reduced in magnitude. However, most of the spatial changes to precipitation in the G2 experiment during geoengineering deployment fail to be statistically significant. Following geoengineering termination, the G1 experiment responds rapidly, with surface and ocean temperatures, NH and SH summer sea ice volume, AMOC transport volume and global precipitation following the same time evolution and reaching those same values found in the 4 × CO2 experiment’s first 10 years. Following geoengineering failure, the G2 run also experiences rapid climate change in all of the variables studied, but does not approach the first 10 years of the 1%CO2yr-1 experiment, because the forcings are quite different in the two runs. Taken together, these results suggest that, while geoengineering to reduce incoming solar radiation could offset the global temperature increase due to increased atmospheric greenhouse gas concentrations, there would be regional warming and cooling, as well as both global and regional impacts on the hydrological cycle. These results also suggest that, should geoengineering suddenly stop, the Earth’s climate would react immediately, with rapid changes in nearly all of the climate variables examined. en_US
dc.language English eng
dc.language.iso en en_US
dc.subject Climate science en_US
dc.subject Geoengineering en_US
dc.subject GeoMIP en_US
dc.subject Atmosphere en_US
dc.subject Climate en_US
dc.subject Sulfate aerosol en_US
dc.subject Solar radiation management en_US
dc.subject Geoengineering failure en_US
dc.subject Geoengineering termination en_US
dc.title Modeled changes to the earth’s climate under a simple geoengineering scheme and following geoengineering failure en_US
dc.type Thesis en_US
dc.contributor.supervisor Gillett, Nathan
dc.contributor.supervisor Weaver, Andrew
dc.degree.department School of Earth and Ocean Sciences en_US
dc.degree.level Master of Science M.Sc. en_US
dc.rights.temp Available to the World Wide Web en_US
dc.description.scholarlevel Graduate en_US


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