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7. Solar irradiance reduction via climate engineering: Impact of different techniques on the energy balance and the hydrological cycle

Author

Niemeier, U., Schmidt, H., https://orcid.org/0000-0001-7977-5041, Alterskjaer, K., and Kristjánsson, J.

Abstract

Different techniques of solar radiation management (SRM) have been suggested to counteract global warming, among them the injection of sulfur into the stratosphere, mirrors in space, and marine cloud brightening through artificial emissions of sea salt. This study focuses on to what extent climate impacts of these three methods would be different. We present results from simulations with an Earth system model where the forcing from the increase of greenhouse gases in a transient scenario (RCP4.5) was balanced over 50 years by SRM. While global mean temperature increases slightly due to the inertia of the climate system and evolves similar with time for the different SRM methods, responses of global mean precipitation differ considerably among the methods. The hydrological sensitivity is decreased by SRM, most prominently for aerosol-based techniques, sea salt emissions, and injection of sulfate into the stratosphere. Reasons for these differences are discussed through an analysis of the surface energy budget. Furthermore, effects on large-scale tropical dynamics and on regional climate are discussed. Key Points First comparison of climate impacts of three climate engineering techniques Global precipitation decreases with all CE methods but differs between methods Impact on tropical dynamics depends on SRM method ©2013. American Geophysical Union. All Rights Reserved.

Published
2013

8. The impact of abrupt suspension of solar radiation management (termination effect) in experiment G2 of the Geoengineering Model Intercomparison Project (GeoMIP)

Author

Jones, A., Haywood, J.M., Alterskjær, K., Boucher, Olivier, Cole, J.N.S., Curry, C.L., Irvine, P.J., Ji, D., Kravitz, B., Egill Kristjánsson, J., Moore, J.C., Niemeier, U., Robock, A., Schmidt, H., Singh, B., Tilmes, S., Watanabe, S., Yoon, J.-H., Met Office Hadley Centre, FitzRoy Road, Exeter, EX1 3PB, United Kingdom, College of Engineering, Mathematics and Physical Sciences [Exeter] (EMPS), University of Exeter, Department of Geosciences [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Canadian Centre for Climate Modelling and Analysis (CCCma), Environment and Climate Change Canada, School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada, Institute for Advanced Sustainability Studies [Potsdam] (IASS), State Key Laboratory of Earth Surface Processes and Resource Ecology (ESPRE), Beijing Normal University (BNU), Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory (PNNL), Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, Department of Environmental Sciences, Rutgers, The State University of New Jersey [New Brunswick] (RU), Rutgers University System (Rutgers)-Rutgers University System (Rutgers), National Center for Atmospheric Research [Boulder] (NCAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology
Abstract

International audience; We have examined changes in climate which result from the sudden termination of geoengineering after 50 years of offsetting a 1% per annum increase in CO2 concentrations by a reduction of solar radiation, as simulated by 11 different climate models in experiment G2 of the Geoengineering Model Intercomparison Project. The models agree on a rapid increase in global-mean temperature following termination accompanied by increases in global-mean precipitation rate and decreases in sea-ice cover. There is no agreement on the impact of geoengineering termination on the rate of change of global-mean plant net primary productivity. There is a considerable degree of consensus for the geographical distribution of temperature change following termination, with faster warming at high latitudes and over land. There is also considerable agreement regarding the distribution of reductions in Arctic sea-ice, but less so for the Antarctic. There is much less agreement regarding the patterns of change in precipitation and net primary productivity, with a greater degree of consensus at higher latitudes. Key Points Impacts of the abrupt termination of geoengineering are compared in 11 GCMsThe models agree on very rapid global-mean warming following terminationLevels of agreement vary on the geographic patterns of climatic change ©2013 Crown copyright. J. Geophys. Res. Atmos. ©2013 American Geophysical Union. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.

Published
2013

9. The hydrological impact of geoengineering in the Geoengineering Model Intercomparison Project (GeoMIP)

Author

Tilmes, S., Fasullo, J., Lamarque, J.-F., Marsh, D.R., Mills, M., Alterskjær, K., Muri, H., Kristjánsson, J.E., Boucher, Olivier, Schulz, M, Cole, J.N.S., Curry, C.L., Jones, A., Haywood, J., Irvine, P.J., Ji, D., Moore, J.C., Bou Karam, Diana, Kravitz, B., Rasch, P.J., Singh, B., Yoon, J.-H., Niemeier, U., Schmidt, H., Robock, A., Yang, S., Watanabe, S., National Center for Atmospheric Research [Boulder] (NCAR), Department of Geosciences [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Canadian Centre for Climate Modelling and Analysis (CCCma), Environment and Climate Change Canada, School of Earth and Ocean Sciences [Victoria] (SEOS), University of Victoria [Canada] (UVIC), Met Office Hadley Centre for Climate Change (MOHC), United Kingdom Met Office [Exeter], University of Exeter, Institute for Advanced Sustainability Studies [Potsdam] (IASS), State Key Laboratory of Earth Surface Processes and Resource Ecology (ESPRE), Beijing Normal University (BNU), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Pacific Northwest National Laboratory (PNNL), Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, Rutgers, The State University of New Jersey [New Brunswick] (RU), Rutgers University System (Rutgers), Danish Meteorological Institute (DMI), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract

International audience; The hydrological impact of enhancing Earth's albedo by solar radiation management is investigated using simulations from 12 Earth System models contributing to the Geoengineering Model Intercomparison Project (GeoMIP). We contrast an idealized experiment, G1, where the global mean radiative forcing is kept at preindustrial conditions by reducing insolation while the CO 2 concentration is quadrupled to a 4×CO2 experiment. The reduction of evapotranspiration over land with instantaneously increasing CO2 concentrations in both experiments largely contributes to an initial reduction in evaporation. A warming surface associated with the transient adjustment in 4×CO2 generates an increase of global precipitation by around 6.9% with large zonal and regional changes in both directions, including a precipitation increase of 10% over Asia and a reduction of 7% for the North American summer monsoon. Reduced global evaporation persists in G1 with temperatures close to preindustrial conditions. Global precipitation is reduced by around 4.5%, and significant reductions occur over monsoonal land regions: East Asia (6%), South Africa (5%), North America (7%), and South America (6%). The general precipitation performance in models is discussed in comparison to observations. In contrast to the 4×CO2 experiment, where the frequency of months with heavy precipitation intensity is increased by over 50% in comparison to the control, a reduction of up to 20% is simulated in G1. These changes in precipitation in both total amount and frequency of extremes point to a considerable weakening of the hydrological cycle in a geoengineered world.

Published
2013

10. Climate model response from the Geoengineering Model Intercomparison Project (GeoMIP)

Author

Kravitz, ., Caldeira, K., Boucher, O., Robock, A., Rasch, P., Alterskjær, K., Bou Karam, D., Cole, J., Curry, C., Haywood, J., Irvine, P., Ji, D., Jones, A., Kristjánsson, J., Lunt, D., Moore, J., Niemeier, U., Schmidt, H., Schulz, M., Singh, B., Tilmes, S., Watanabe, S., Yang, S., Yoon, J., Pacific Northwest National Laboratory (PNNL), Department of Global Ecology [Carnegie] (DGE), Carnegie Institution for Science, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Department of Environmental Sciences [New Brunswick], School of Environmental and Biological Sciences [New Brunswick], Rutgers, The State University of New Jersey [New Brunswick] (RU), Rutgers University System (Rutgers)-Rutgers University System (Rutgers)-Rutgers, The State University of New Jersey [New Brunswick] (RU), Rutgers University System (Rutgers)-Rutgers University System (Rutgers), Department of Geosciences [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Canadian Centre for Climate Modelling and Analysis (CCCma), Environment and Climate Change Canada, School of Earth and Ocean Sciences, University of Victoria, Victoria BC, Canada, Met Office Hadley Centre for Climate Change (MOHC), United Kingdom Met Office [Exeter], College of Engineering, Mathematics and Physical Sciences [Exeter] (EMPS), University of Exeter, Institute for Advanced Sustainability Studies [Potsdam] (IASS), State Key Laboratory of Earth Surface Processes and Resource Ecology (ESPRE), Beijing Normal University (BNU), University of Bristol [Bristol], Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, Norwegian Meteorological Institute [Oslo] (MET), National Center for Atmospheric Research [Boulder] (NCAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Danish Meteorological Institute (DMI), Carnegie Institution for Science [Washington], Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)

Subjects
model intercomparison, geoengineering, [SDU]Sciences of the Universe [physics], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Earth Science
Abstract

International audience; Solar geoengineering - deliberate reduction in the amount of solar radiation retained by the Earth - has been proposed as a means of counteracting some of the climatic effects of anthropogenic greenhouse gas emissions. We present results from Experiment G1 of the Geoengineering Model Intercomparison Project, in which 12 climate models have simulated the climate response to an abrupt quadrupling of CO2 from preindustrial concentrations brought into radiative balance via a globally uniform reduction in insolation. Models show this reduction largely offsets global mean surface temperature increases due to quadrupled CO2 concentrations and prevents 97% of the Arctic sea ice loss that would otherwise occur under high CO2 levels but, compared to the preindustrial climate, leaves the tropics cooler (-0.3 K) and the poles warmer (+0.8 K). Annual mean precipitation minus evaporation anomalies for G1 are less than 0.2 mm day-1 in magnitude over 92% of the globe, but some tropical regions receive less precipitation, in part due to increased moist static stability and suppression of convection. Global average net primary productivity increases by 120% in G1 over simulated preindustrial levels, primarily from CO2 fertilization, but also in part due to reduced plant heat stress compared to a high CO2 world with no geoengineering. All models show that uniform solar geoengineering in G1 cannot simultaneously return regional and global temperature and hydrologic cycle intensity to preindustrial levels. Key Points Temperature reduction from uniform geoengineering is not uniform Geoengineering cannot offset both temperature and hydrology changes NPP increases mostly due to CO2 fertilization ©2013. American Geophysical Union. All Rights Reserved.

Published
2013

11. Solar irradiance reduction to counteract radiative forcing from a quadrupling of CO2 : climate responses simulated by four earth system models

Author

Schmidt, H., https://orcid.org/0000-0001-7977-5041, Alterskjaer, K., Bou Karam, D., Boucher, O., Jones, A., Kristjansson, J., Niemeier, U., Schulz, M., Aaheim, A., Benduhn, F., Lawrence, M., Timmreck, C., Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
lcsh:Geology, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:Dynamic and structural geology, lcsh:QE500-639.5, lcsh:QE1-996.5, lcsh:Q, lcsh:Science, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment
Abstract

International audience; Abstract. In this study we compare the response of four state-of-the-art Earth system models to climate engineering under scenario G1 of two model intercomparison projects: GeoMIP (Geoengineering Model Intercomparison Project) and IMPLICC (EU project "Implications and risks of engineering solar radiation to limit climate change"). In G1, the radiative forcing from an instantaneous quadrupling of the CO2 concentration, starting from the preindustrial level, is balanced by a reduction of the solar constant. Model responses to the two counteracting forcings in G1 are compared to the preindustrial climate in terms of global means and regional patterns and their robustness. While the global mean surface air temperature in G1 remains almost unchanged compared to the control simulation, the meridional temperature gradient is reduced in all models. Another robust response is the global reduction of precipitation with strong effects in particular over North and South America and northern Eurasia. In comparison to the climate response to a quadrupling of CO2 alone, the temperature responses are small in experiment G1. Precipitation responses are, however, in many regions of comparable magnitude but globally of opposite sign.

Published
2012

21. Can a reduction of solar irradiance counteract CO2-induced climate change? - Results from four Earth system models.

Author

Schmidt, H., Alterskjær, K., Karam, D. Bou, Boucher, O., Jones, A., Kristjansson, J. E., Niemeier, U., Schulz, M., Aaheim, A., Benduhn, F., Lawrence, M., and Timmreck1, C.

Subjects
*CLIMATE change, *GLOBAL warming, *ATMOSPHERIC temperature, *ENVIRONMENTAL engineering, *EVAPORATION (Meteorology)
Abstract

The article presents a study on the comparison of four Earth system models to climate engineering. The study compared the two couteracting forcings I G1 of the GeoMIP to the preindustrial climate. The result of the study shows that the reduction in evaporation compensated the reduction of the meridional temperature gradient in all models compared to the control simulation.

Published
2012
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22. Solar irradiance reduction to counteract radiative forcing from a quadrupling of CO2: climate responses simulated by four earth system models.

Author

Schmidt, H., Alterskjær, K., Bou Karam, D., Boucher, O., Jones, A., Kristjánsson, J. E., Niemeier, U., Schulz, M., Aaheim, A., Benduhn, F., Lawrence, M., and Timmreck, C.

Subjects
*CLIMATE change models, *SOLAR constant, *RADIATIVE forcing, *CARBON dioxide, *TEMPERATURE
Abstract

The article presents a study which focuses on the comparison of the response of four Earth system models to climate change engineering under the scenario G1 of the Geoengineering Model Intercomparison Project (GeoMIP). The study uses the reduction of the solar constant to balance the radiative forcing from an instantaneous quadrupling of the carbon dioxide (CO2) concentration in G1. Results show that temperature responses are small in G1 as compared with the CO2 alone.

Published
2012
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23. Sensitivity to deliberate sea salt seeding of marine clouds -- observations and model simulations.

Author

Alterskjær, K., Kristjánsson, J. E., and Seland, Ø.

Abstract

Sea salt seeding of marine clouds to increase their albedo is a proposed technique to counteract or slow global warming. In this study, we first investigate the susceptibility of marine clouds to sea salt injections, using observational data of cloud droplet number concentration, cloud optical depth, and liquid cloud fraction from the MODIS (Moderate Resolution Imaging Spectroradiometer) instruments on board the Aqua and Terra satellites. We then compare the derived susceptibility function to a corresponding estimate from the Norwegian Earth System Model (NorESM). Results compare well between simulations and observations, showing that stratocumulus regions of the west coast of the major continents along with large regions in the Pacific and the Indian Oceans are susceptible. We then carry out geo-engineering experiments with a uniform increase of 10-9 kg m-2 s-1 in emissions of sea salt particles with a modal radius of 0.13 µm. The increased sea salt concentrations and the resulting change in marine cloud properties lead to a globally averaged forcing of -4.8 W m-2 at the top of the atmosphere, more than cancelling a doubling of CO2 concentrations. The forcing is large in areas found to be sensitive by using the susceptibility function, confirming its usefulness as an indicator of where to inject sea salt for maximum effect. Results also show that the effectiveness of sea salt seeding is reduced because the injected sea salt provide a large surface area for water vapor and gaseous sulphuric acid to condense on, thereby lowering the maximum supersaturation and suppressing the formation and lifetime of sulphate particles. In some areas, our simulations show an overall reduction in the CCN concentration and the number of activated cloud droplets decreases, resulting in a positive globally averaged forcing. [ABSTRACT FROM AUTHOR]

Published
2011
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