Climatic impacts of stratospheric geoengineering with sulfate, black carbon and titania injection

Abstract. In this paper, we examine the potential climatic effects of geoengineering by sulfate, black carbon and titania injection against a baseline RCP8.5 scenario. We use the HadGEM2-CCS model to simulate scenarios in which the top-of-the-atmosphere radiative imbalance due to rising greenhouse gas concentrations is offset by sufficient aerosol injection throughout the 2020–2100 period. We find that the global-mean temperature is effectively maintained at historical levels for the entirety of the period for all three aerosol-injection scenarios, though there is a wide range of side-effects which are discussed in detail. The most prominent conclusion is that although the BC injection rate necessary to produce an equivalent global mean temperature response is much lower, the severity of stratospheric temperature changes (> +70 °C) and precipitation impacts effectively exclude BC from being a viable option for geoengineering. Additionally, while it has been suggested that titania would be an effective particle because of its high scattering efficiency, it also efficiently absorbs solar ultraviolet radiation producing a significant stratospheric warming (> +20 °C). As injection rates and climatic impacts for titania are close to those for sulfate, there appears to be little benefit in terms of climatic influence of using titania when compared to the injection of sulfur dioxide, which has the added benefit of being well-modeled through extensive research that has been carried out on naturally occurring explosive volcanic eruptions.

[1]  Corinne Le Quéré,et al.  The challenge to keep global warming below 2 °C , 2013 .

[2]  Paul A. O'Gorman,et al.  An energetic perspective on the regional response of precipitation to climate change , 2011 .

[3]  V. Eyring.  Coupled Model Intercomparison Project Phase 6 (CMIP6) - an Overview of Activities , 2015 .

[4]  Robert Benjamin Lee,et al.  Radiometric Performance of the CERES Earth Radiation Budget Climate Record Sensors on the EOS Aqua and Terra Spacecraft through April 2007 , 2011 .

[5]  Luke D. Oman,et al.  Dispersion of the volcanic sulfate cloud from a Mount Pinatubo–like eruption , 2012 .

[6]  Lieven Clarisse,et al.  Observations of the eruption of the Sarychev volcano and simulations using the HadGEM2 climate model. , 2010 .

[7]  Philip J. Rasch,et al.  Explicit feedback and the management of uncertainty in meeting climate objectives with solar geoengineering , 2014 .

[8]  Shingo Watanabe,et al.  The hydrological impact of geoengineering in the Geoengineering Model Intercomparison Project (GeoMIP) , 2013 .

[9]  Shingo Watanabe,et al.  The Geoengineering Model Intercomparison Project Phase 6 (GeoMIP6): simulation design and preliminary results , 2015 .

[10]  E. Teller,et al.  Global warming and ice ages: I. prospects for physics based modulation of global change , 1996 .

[11]  V. Aquila,et al.  Stratospheric ozone response to sulfate geoengineering: Results from the Geoengineering Model Intercomparison Project (GeoMIP) , 2014 .

[12]  Mark Lawrence,et al.  An overview of the Geoengineering Model Intercomparison Project (GeoMIP) , 2013 .

[13]  C. Brühl,et al.  Multimodel assessment of the upper troposphere and lower stratosphere: Tropics and global trends , 2010 .

[14]  K. Rosenlof,et al.  Stratospheric water vapor feedback , 2013, Proceedings of the National Academy of Sciences.

[15]  K. Krüger,et al.  Variations of the residual circulation in the Northern Hemispheric winter , 2008 .

[16]  P. Crutzen.  Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution to Resolve a Policy Dilemma? , 2006 .

[17]  M. King,et al.  The effect of snow/sea ice type on the response of albedo and light penetration depth ( e -folding depth) to increasing black carbon , 2014 .

[18]  J. M. English,et al.  Microphysical simulations of sulfur burdens from stratospheric sulfur geoengineering , 2012 .

[19]  Martin Wild,et al.  The roles of aerosol, water vapor and cloud in future global dimming/brightening , 2011 .

[20]  Riko Oki,et al.  The EarthCARE Satellite: The Next Step Forward in Global Measurements of Clouds, Aerosols, Precipitation, and Radiation , 2015 .

[21]  Eric P. Shettle,et al.  Atmospheric Aerosols: Global Climatology and Radiative Characteristics , 1991 .

[22]  P. Rasch,et al.  An overview of geoengineering of climate using stratospheric sulphate aerosols , 2008, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[23]  F. Zwiers,et al.  Changes in temperature and precipitation extremes in the CMIP5 ensemble , 2013, Climatic Change.

[24]  D. Weisenstein,et al.  The impact of geoengineering aerosols on stratospheric temperature and ozone , 2009 .

[25]  O. Boucher,et al.  Aerosol forcing in the Climate Model Intercomparison Project (CMIP5) simulations by HadGEM2‐ES and the role of ammonium nitrate , 2011 .

[26]  C. Tebaldi,et al.  Long-term Climate Change: Projections, Commitments and Irreversibility , 2013 .

[27]  J. Shepherd,et al.  Geoengineering the Climate: Science, Governance and Uncertainty , 2009 .

[28]  Douglas G. MacMartin,et al.  Dynamics of the coupled human–climate system resulting from closed-loop control of solar geoengineering , 2014, Climate Dynamics.

[29]  B. Colle,et al.  Evaluation of Historical and Future Cool Season Precipitation over the Eastern United States and Western Atlantic Storm Track Using CMIP5 Models , 2015 .

[30]  Hauke Schmidt,et al.  Solar irradiance reduction via climate engineering: Impact of different techniques on the energy balance and the hydrological cycle , 2013 .

[31]  Rolando R. Garcia,et al.  Impact of very short-lived halogens on stratospheric ozone abundance and UV radiation in a geo-engineered atmosphere , 2012 .

[32]  Y. Kawatani,et al.  Weakened stratospheric quasibiennial oscillation driven by increased tropical mean upwelling , 2013, Nature.

[33]  D. Weisenstein,et al.  Solar geoengineering using solid aerosol in the stratosphere , 2015 .

[34]  G. Mann,et al.  An AeroCom Assessment of Black Carbon in Arctic Snow and Sea Ice , 2013 .

[35]  M. Petters,et al.  Hygroscopicity and cloud droplet activation of mineral dust aerosol , 2009 .

[36]  Ken Caldeira,et al.  Management of trade-offs in geoengineering through optimal choice of non-uniform radiative forcing , 2013 .

[37]  C. Bitz,et al.  Inability of stratospheric sulfate aerosol injections to preserve the West Antarctic Ice Sheet , 2015 .

[38]  Luke D. Oman,et al.  Modifications of the quasi‐biennial oscillation by a geoengineering perturbation of the stratospheric aerosol layer , 2014 .

[39]  Andrew Charlton-Perez,et al.  Stratospheric heating by potential geoengineering aerosols , 2011 .

[40]  R. Stolarski,et al.  Comparison of lower stratospheric tropical mean vertical velocities , 2008 .

[41]  E. Highwood,et al.  Weakened tropical circulation and reduced precipitation in response to geoengineering , 2014 .

[42]  J. Klett,et al.  Microphysics of Clouds and Precipitation , 1978, Nature.

[43]  A. Robock,et al.  Coupled Model Intercomparison Project 5 (CMIP5) simulations of climate following volcanic eruptions , 2012 .

[44]  C. Jones,et al.  The HadGEM2 family of Met Office Unified Model climate configurations , 2011 .

[45]  K. Taylor,et al.  The Geoengineering Model Intercomparison Project (GeoMIP) , 2011 .

[46]  James Hansen,et al.  An imperative to monitor Earth's energy imbalance , 2016 .

[47]  B. Kravitz,et al.  Sensitivity of stratospheric geoengineering with black carbon to aerosol size and altitude of injection , 2012 .

[48]  T. Mauritsen,et al.  Arctic amplification dominated by temperature feedbacks in contemporary climate models , 2014 .

[49]  K. Calvin,et al.  The RCP greenhouse gas concentrations and their extensions from 1765 to 2300 , 2011 .

[50]  Kevin Hamilton,et al.  The quasi‐biennial oscillation , 2001 .

[51]  Ning Pan,et al.  Studying the mechanisms of titanium dioxide as ultraviolet‐blocking additive for films and fabrics by an improved scheme , 2004 .

[52]  R. A. Cox,et al.  Heterogeneous reaction of N 2 O 5 with airborne TiO 2 particles and its implication for stratospheric particle injection , 2014 .

[53]  Andrew Gettelman,et al.  Impact of geoengineered aerosols on the troposphere and stratosphere , 2009 .

[54]  G. Mann,et al.  Aerosol microphysics simulations of the Mt.~Pinatubo eruption with the UM-UKCA composition-climate model , 2014 .

[55]  D. Weisenstein,et al.  Efficient formation of stratospheric aerosol for climate engineering by emission of condensible vapor from aircraft , 2010 .

[56]  C. Timmreck,et al.  The dependency of geoengineered sulfate aerosol on the emission strategy , 2011 .

[57]  Georgiy L. Stenchikov,et al.  Regional climate responses to geoengineering with tropical and Arctic SO2 injections , 2008 .

[58]  K. Taylor,et al.  Impact of geoengineering schemes on the global hydrological cycle , 2008, Proceedings of the National Academy of Sciences.

[59]  Karl E. Taylor,et al.  An overview of CMIP5 and the experiment design , 2012 .

[60]  C. Timmreck,et al.  Response of the middle atmosphere to anthropogenic and natural forcings in the CMIP5 simulations with the Max Planck Institute Earth system model , 2013 .

[61]  B. Kravitz,et al.  Arctic cryosphere response in the Geoengineering Model Intercomparison Project G3 and G4 scenarios , 2014 .

[62]  Andrew S. Jones,et al.  Asymmetric forcing from stratospheric aerosols impacts Sahelian rainfall , 2013 .

[63]  Y. Balkanski,et al.  Photoenhanced uptake of NO2 on mineral dust: Laboratory experiments and model simulations , 2008 .

[64]  R. A. Cox,et al.  Stratospheric aerosol particles and solar-radiation management , 2012 .

[65]  G. Mcfiggans,et al.  Ambient black carbon particle hygroscopic properties controlled by mixing state and composition , 2012 .

[66]  E. Fetzer,et al.  The Observed State of the Energy Budget in the Early Twenty-First Century , 2015 .

[67]  V. Ramaswamy,et al.  Arctic Oscillation response to the 1991 Mount Pinatubo eruption: Effects of volcanic aerosols and ozone depletion , 2002 .

[68]  J. Hansen,et al.  Radiative forcing and climate response , 1997 .

[69]  A. Robock,et al.  High‐latitude eruptions cast shadow over the African monsoon and the flow of the Nile , 2006 .

[70]  Duoying Ji,et al.  Impacts, effectiveness and regional inequalities of the GeoMIP G1 to G4 solar radiation management scenarios , 2015 .