scholarly journals Radiative and climate effects of stratospheric sulfur geoengineering using seasonally varying injection areas

2017 ◽  
Vol 17 (11) ◽  
pp. 6957-6974 ◽  
Author(s):  
Anton Laakso ◽  
Hannele Korhonen ◽  
Sami Romakkaniemi ◽  
Harri Kokkola
Keyword(s):  
Solar Radiation ◽  
Radiative Forcing ◽  
Climate Model ◽  
Cost Effective ◽  
Solar Radiation Management ◽  
Management Scenarios ◽  
Zonal Distribution ◽  
Climate Effects ◽  
Low Latitudes ◽  
Radiation Management

Abstract. Stratospheric sulfur injections have often been suggested as a cost-effective geoengineering method to prevent or slow down global warming. In geoengineering studies, these injections are commonly targeted to the Equator, where the yearly mean intensity of the solar radiation is the highest and from where the aerosols disperse globally due to the Brewer–Dobson Circulation. However, compensating for greenhouse gas-induced zonal warming by reducing solar radiation would require a relatively larger radiative forcing to the mid- and high latitudes and a lower forcing to the low latitudes than what is achieved by continuous equatorial injections. In this study we employ alternative aerosol injection scenarios to investigate if the resulting radiative forcing can be targeted to be zonally more uniform without decreasing the global the mean radiative forcing of stratospheric sulfur geoengineering. We used a global aerosol–climate model together with an Earth system model to study the radiative and climate effects of stratospheric sulfur injection scenarios with different injection areas. According to our simulations, varying the SO2 injection area seasonally would result in a similar global mean cooling effect as injecting SO2 to the Equator, but with a more uniform zonal distribution of shortwave radiative forcing. Compared to the case of equatorial injections, in the seasonally varying injection scenario where the maximum sulfur production from injected SO2 followed the maximum of solar radiation, the shortwave radiative forcing decreased by 27 % over the Equator (the latitudes between 20° N and 20° S) and increased by 15 % over higher latitudes. Compared to the continuous injections to the Equator, in summer months the radiative forcing was increased by 17 and 14 % and in winter months decreased by 14 and 16 % in Northern and Southern hemispheres, respectively. However, these forcings do not translate into as large changes in temperatures. The changes in forcing would only lead to 0.05 K warmer winters and 0.05 K cooler summers in the Northern Hemisphere, which is roughly 3 % of the cooling resulting from solar radiation management scenarios studied here.

scholarly journals Radiative and climate effects of stratospheric sulfur geoengineering using seasonally varying injection areas

2017 ◽  
Author(s):  
Anton Laakso ◽  
Hannele Korhonen ◽  
Sami Romakkaniemi ◽  
Harri Kokkola
Keyword(s):  
Temperature Gradient ◽  
Solar Radiation ◽  
Radiative Forcing ◽  
Climate Model ◽  
Cost Effective ◽  
Solar Radiation Management ◽  
Meridional Temperature Gradient ◽  
Management Scenarios ◽  
Zonal Distribution ◽  
Climate Effects

Abstract. Stratospheric sulfur injections have often been suggested as a cost effective geoengineering method to prevent or slow down global warming. In geoengineering studies these injections are commonly targeted to the equator, where the intensity of the solar radiation is highest. However, it may not be the most optimal aerosol injection strategy because the radiative forcing concentrating over the equator decreases the meridional temperature gradient. In this study we employ alternative aerosol injection scenarios to investigate if the resulting radiative forcing can be optimized to be zonally more uniform without decreasing the global efficacy. We used a global aerosol-climate model together with an Earth system model to study the radiative and climate effects of stratospheric sulfur injection scenarios with different injection areas. According to our simulations, varying the SO2 injection area seasonally would result in a similar global mean cooling effect as injecting SO2 to the equator, but with a more uniform zonal distribution of shortwave radiative forcing. Compared to the case of equatorial injections, in the optimized injection scenario where the maximum sulfur production from injected SO2 followed the maximum of solar radiation, the shortwave radiative forcing decreased by 27 % over the equator (between the latitudes between 20° N and 20° S) and increased by 15 % over higher latitudes. Compared to the continuous injections to equator, in summer months the radiative forcing was increased by 17 % and 14 % and winter months decreased by −14 % and −16 % at northern and southern hemispheres respectively. However, these forcings do not translate into very significant changes in temperatures. Based on ESM simulations, changes in forcing would lead only to 0.05 K warmer winters and 0.05 K cooler summers at the northern hemisphere which is roughly 3 % of the cooling resulted from solar radiation management scenarios studied here. At the same time the meridional temperature gradient was better maintained.

scholarly journals Interactions between reducing CO 2 emissions, CO 2 removal and solar radiation management

2012 ◽  
Vol 370 (1974) ◽  
pp. 4343-4364 ◽  
Author(s):  
Naomi E. Vaughan ◽  
Timothy M. Lenton
Keyword(s):  
Carbon Dioxide ◽  
Solar Radiation ◽  
Carbon Dioxide Emissions ◽  
Radiative Forcing ◽  
Carbon Capture ◽  
Climate Model ◽  
Carbon Capture And Storage ◽  
Solar Radiation Management ◽  
Radiation Management ◽  
And Storage

We use a simple carbon cycle–climate model to investigate the interactions between a selection of idealized scenarios of mitigated carbon dioxide emissions, carbon dioxide removal (CDR) and solar radiation management (SRM). Two CO 2 emissions trajectories differ by a 15-year delay in the start of mitigation activity. SRM is modelled as a reduction in incoming solar radiation that fully compensates the radiative forcing due to changes in atmospheric CO 2 concentration. Two CDR scenarios remove 300 PgC by afforestation (added to vegetation and soil) or 1000 PgC by bioenergy with carbon capture and storage (removed from system). Our results show that delaying the start of mitigation activity could be very costly in terms of the CDR activity needed later to limit atmospheric CO 2 concentration (and corresponding global warming) to a given level. Avoiding a 15-year delay in the start of mitigation activity is more effective at reducing atmospheric CO 2 concentrations than all but the maximum type of CDR interventions. The effects of applying SRM and CDR together are additive, and this shows most clearly for atmospheric CO 2 concentration. SRM causes a significant reduction in atmospheric CO 2 concentration due to increased carbon storage by the terrestrial biosphere, especially soils. However, SRM has to be maintained for many centuries to avoid rapid increases in temperature and corresponding increases in atmospheric CO 2 concentration due to loss of carbon from the land.

scholarly journals Heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> with airborne TiO<sub>2</sub> particles and its implication for stratospheric particle injection

2014 ◽  
Vol 14 (4) ◽  
pp. 4421-4456 ◽  
Author(s):  
M. J. Tang ◽  
P. J. Telford ◽  
F. D. Pope ◽  
L. Rkiouak ◽  
N. L. Abraham ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Climate Model ◽  
Heterogeneous Reaction ◽  
High Refractive Index ◽  
Heterogeneous Reactions ◽  
Solar Radiation Management ◽  
Particle Injection ◽  
Stratospheric Chemistry ◽  
Radiation Management ◽  
The Impact

Abstract. Injection of aerosol particles (or their precursors) into the stratosphere to scatter solar radiation back into space, has been suggested as a solar-radiation management scheme for the mitigation of global warming. TiO2 has recently been highlighted as a possible candidate particle because of its high refractive index, but its impact on stratospheric chemistry via heterogeneous reactions is as yet unknown. In this work the heterogeneous reaction of airborne sub-micrometre TiO2 particles with N2O5 has been investigated for the first time, at room temperature and different relative humidities (RH), using an atmospheric pressure aerosol flow tube. The uptake coefficient of N2O5 onto TiO2, γ(N2O5), was determined to be ∼ 1.0 × 10−3 at low RH, increasing to ∼ 3 × 10−3 at 60% RH. The uptake of N2O5 onto TiO2 is then included in the UKCA chemistry climate model to assess the impact of this reaction on stratospheric chemistry. While the impact of TiO2 on the scattering of solar radiation is chosen to be similar to the aerosol from the Mt. Pinatubo eruption, the impact of TiO2 injection on stratospheric N2O5 is much smaller.

scholarly journals Field experiments on solar geoengineering: report of a workshop exploring a representative research portfolio

2014 ◽  
Vol 372 (2031) ◽  
pp. 20140175 ◽  
Author(s):  
David W. Keith ◽  
Riley Duren ◽  
Douglas G. MacMartin
Keyword(s):  
Solar Radiation ◽  
Radiative Forcing ◽  
Field Experiments ◽  
Field Research ◽  
Research Programme ◽  
Solar Radiation Management ◽  
Systematic Research ◽  
Cirrus Cloud ◽  
Solar Geoengineering ◽  
Radiation Management

We summarize a portfolio of possible field experiments on solar radiation management (SRM) and related technologies. The portfolio is intended to support analysis of potential field research related to SRM including discussions about the overall merit and risk of such research as well as mechanisms for governing such research and assessments of observational needs. The proposals were generated with contributions from leading researchers at a workshop held in March 2014 at which the proposals were critically reviewed. The proposed research dealt with three major classes of SRM proposals: marine cloud brightening, stratospheric aerosols and cirrus cloud manipulation. The proposals are summarized here along with an analysis exploring variables such as space and time scale, risk and radiative forcing. Possible gaps, biases and cross-cutting considerations are discussed. Finally, suggestions for plausible next steps in the development of a systematic research programme are presented.

scholarly journals Substantial Climate Response outside the Target Area in an Idealized Experiment of Regional Radiation Management

Climate ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 66
Author(s):  
Sudhakar Dipu ◽  
Johannes Quaas ◽  
Martin Quaas ◽  
Wilfried Rickels ◽  
Johannes Mülmenstädt ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Heat Waves ◽  
Climate Impacts ◽  
The Arctic ◽  
Solar Radiation Management ◽  
Target Area ◽  
Local Cooling ◽  
Target Region ◽  
Radiation Management

Radiation management (RM) has been proposed as a conceivable climate engineering (CE) intervention to mitigate global warming. In this study, we used a coupled climate model (MPI-ESM) with a very idealized setup to investigate the efficacy and risks of CE at a local scale in space and time (regional radiation management, RRM) assuming that cloud modification is technically possible. RM is implemented in the climate model by the brightening of low-level clouds (solar radiation management, SRM) and thinning of cirrus (terrestrial radiation management, TRM). The region chosen is North America, and we simulated a period of 30 years. The implemented sustained RM resulted in a net local radiative forcing of −9.8 Wm−2 and a local cooling of −0.8 K. Surface temperature (SAT) extremes (90th and 10th percentiles) show negative anomalies in the target region. However, substantial climate impacts were also simulated outside the target area, with warming in the Arctic and pronounced precipitation change in the eastern Pacific. As a variant of RRM, a targeted intervention to suppress heat waves (HW) was investigated in further simulations by implementing intermittent cloud modification locally, prior to the simulated HW situations. In most cases, the intermittent RRM results in a successful reduction of temperatures locally, with substantially smaller impacts outside the target area compared to the sustained RRM.

scholarly journals What is the limit of stratospheric sulfur climate engineering?

2015 ◽  
Vol 15 (7) ◽  
pp. 10939-10969 ◽  
Author(s):  
U. Niemeier ◽  
C. Timmreck
Keyword(s):  
Sulfur Dioxide ◽  
Solar Radiation ◽  
Radiative Forcing ◽  
Stratospheric Aerosol ◽  
Solar Radiation Management ◽  
Aerosol Layer ◽  
Aerosol Model ◽  
Model Studies ◽  
Radiation Management ◽  
Business As Usual

Abstract. The injection of sulfur dioxide (SO2) into the stratosphere to form an artificial stratospheric aerosol layer is considered as an option for solar radiation management. The related reduction in radiative forcing depends upon the amount injected of sulfur dioxide but aerosol model studies indicate a decrease in forcing efficiency with increasing injection magnitude. None of these studies, however, consider injection strengths greater than 10 Tg(S) yr-1. This would be necessary to counteract the strong anthropogenic forcing expected if "business as usual" emission conditions continue throughout this century. To understand the effects of the injection of larger amounts of SO2 we have calculated the effects of SO2 injections up to 100 Tg(S) yr-1. We estimate the reliability of our results through consideration of various injection strategies, and from comparison with results obtained from other models. Our calculations show that the efficiency of the aerosol layer, expressed as the relationship between sulfate aerosol forcing and injection strength, decays exponentially. This result implies that the solar radiation management strategy required to keep temperatures constant at that anticipated for 2020, whilst maintaining "business as usual" conditions, would require atmospheric injections of the order of 45 Tg(S) yr-1 which amounts to 6 times that emitted from of the Mt. Pinatubo eruption each year.

scholarly journals Impacts, effectiveness and regional inequalities of the GeoMIP G1 to G4 solar radiation management scenarios

2015 ◽  
Vol 129 ◽  
pp. 10-22 ◽  
Author(s):  
Xiaoyong Yu ◽  
John C. Moore ◽  
Xuefeng Cui ◽  
Annette Rinke ◽  
Duoying Ji ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Solar Radiation Management ◽  
Management Scenarios ◽  
Regional Inequalities ◽  
Radiation Management

scholarly journals Heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> with airborne TiO<sub>2</sub> particles and its implication for stratospheric particle injection

2014 ◽  
Vol 14 (12) ◽  
pp. 6035-6048 ◽  
Author(s):  
M. J. Tang ◽  
P. J. Telford ◽  
F. D. Pope ◽  
L. Rkiouak ◽  
N. L. Abraham ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Climate Model ◽  
Heterogeneous Reaction ◽  
High Refractive Index ◽  
Heterogeneous Reactions ◽  
Solar Radiation Management ◽  
Particle Injection ◽  
Stratospheric Chemistry ◽  
Radiation Management ◽  
The Impact

Abstract. Injection of aerosol particles (or their precursors) into the stratosphere to scatter solar radiation back into space has been suggested as a solar-radiation management scheme for the mitigation of global warming. TiO2 has recently been highlighted as a possible candidate particle because of its high refractive index, but its impact on stratospheric chemistry via heterogeneous reactions is as yet unknown. In this work the heterogeneous reaction of airborne sub-micrometre TiO2 particles with N2O5 has been investigated for the first time, at room temperature and different relative humidities (RH), using an atmospheric pressure aerosol flow tube. The uptake coefficient of N2O5 onto TiO2, γ(N2O5), was determined to be ~1.0 × 10−3 at low RH, increasing to ~3 × 10−3 at 60% RH. The uptake of N2O5 onto TiO2 is then included in the UKCA chemistry–climate model to assess the impact of this reaction on stratospheric chemistry. While the impact of TiO2 on the scattering of solar radiation is chosen to be similar to the aerosol from the Mt Pinatubo eruption, the impact of TiO2 injection on stratospheric N2O5 is much smaller.

scholarly journals What is the limit of climate engineering by stratospheric injection of SO<sub>2</sub>?

2015 ◽  
Vol 15 (16) ◽  
pp. 9129-9141 ◽  
Author(s):  
U. Niemeier ◽  
C. Timmreck
Keyword(s):  
Sulfur Dioxide ◽  
Solar Radiation ◽  
Radiative Forcing ◽  
Stratospheric Aerosol ◽  
Injection Rate ◽  
Solar Radiation Management ◽  
Aerosol Layer ◽  
Aerosol Model ◽  
Radiation Management ◽  
Business As Usual

Abstract. The injection of sulfur dioxide (SO2) into the stratosphere to form an artificial stratospheric aerosol layer is discussed as an option for solar radiation management. The related reduction of radiative forcing depends upon the injected amount of sulfur dioxide, but aerosol model studies indicate a decrease in forcing efficiency with increasing injection rate. None of these studies, however, consider injection rates greater than 20 Tg(S) yr−1. But this would be necessary to counteract the strong anthropogenic forcing expected if "business as usual" emission conditions continue throughout this century. To understand the effects of the injection of larger amounts of SO2, we have calculated the effects of SO2 injections up to 100 Tg(S) yr−1. We estimate the reliability of our results through consideration of various injection strategies and from comparison with results obtained from other models. Our calculations show that the efficiency of such a geoengineering method, expressed as the ratio between sulfate aerosol forcing and injection rate, decays exponentially. This result implies that the sulfate solar radiation management strategy required to keep temperatures constant at that anticipated for 2020, while maintaining business as usual conditions, would require atmospheric injections of approximately 45 Tg(S) yr−1 (±15 % or 7 Tg(S) yr−1) at a height corresponding to 60 hPa. This emission is equivalent to 5 to 7 times the Mt. Pinatubo eruption each year.

Sign in / Sign up

Export Citation Format

Share Document