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 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 Heterogeneous reaction of ClONO<sub>2</sub> with TiO<sub>2</sub> and SiO<sub>2</sub> aerosol particles: implications for stratospheric particle injection for climate engineering

2016 ◽  
Vol 16 (23) ◽  
pp. 15397-15412 ◽  
Author(s):  
Mingjin Tang ◽  
James Keeble ◽  
Paul J. Telford ◽  
Francis D. Pope ◽  
Peter Braesicke ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Climate Model ◽  
Heterogeneous Reaction ◽  
Stratospheric Ozone ◽  
Aerosol Particles ◽  
Climate Engineering ◽  
Particle Injection ◽  
Stratospheric Chemistry ◽  
Significant Difference ◽  
Hydrolysis Of

Abstract. Deliberate injection of aerosol particles into the stratosphere is a potential climate engineering scheme. Particles injected into the stratosphere would scatter solar radiation back to space, thereby reducing the temperature at the Earth's surface and hence the impacts of global warming. Minerals such as TiO2 or SiO2 are among the potentially suitable aerosol materials for stratospheric particle injection due to their greater light-scattering ability than stratospheric sulfuric acid particles. However, the heterogeneous reactivity of mineral particles towards trace gases important for stratospheric chemistry largely remains unknown, precluding reliable assessment of their impacts on stratospheric ozone, which is of key environmental significance. In this work we have investigated for the first time the heterogeneous hydrolysis of ClONO2 on TiO2 and SiO2 aerosol particles at room temperature and at different relative humidities (RHs), using an aerosol flow tube. The uptake coefficient, γ(ClONO2), on TiO2 was ∼ 1.2 × 10−3 at 7 % RH and remained unchanged at 33 % RH, and increased for SiO2 from ∼ 2 × 10−4 at 7 % RH to  ∼ 5 × 10−4 at 35 % RH, reaching a value of  ∼ 6 × 10−4 at 59 % RH. We have also examined the impacts of a hypothetical TiO2 injection on stratospheric chemistry using the UKCA (United Kingdom Chemistry and Aerosol) chemistry–climate model, in which heterogeneous hydrolysis of N2O5 and ClONO2 on TiO2 particles is considered. A TiO2 injection scenario with a solar-radiation scattering effect very similar to the eruption of Mt Pinatubo was constructed. It is found that, compared to the eruption of Mt Pinatubo, TiO2 injection causes less ClOx activation and less ozone destruction in the lowermost stratosphere, while reduced depletion of N2O5 and NOx in the middle stratosphere results in decreased ozone levels. Overall, no significant difference in the vertically integrated ozone abundances is found between TiO2 injection and the eruption of Mt Pinatubo. Future work required to further assess the impacts of TiO2 injection on stratospheric chemistry is also discussed.

scholarly journals Heterogeneous reaction of ClONO<sub>2</sub> with TiO<sub>2</sub> and SiO<sub>2</sub> aerosol particles: implications for stratospheric particle injection for climate engineering

2016 ◽  
Author(s):  
M. J. Tang ◽  
J. Keeble ◽  
P. J. Telford ◽  
F. D. Pope ◽  
P. Braesicke ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Climate Model ◽  
Heterogeneous Reaction ◽  
Stratospheric Ozone ◽  
Aerosol Particles ◽  
Climate Engineering ◽  
Particle Injection ◽  
Stratospheric Chemistry ◽  
Significant Difference ◽  
Hydrolysis Of

Abstract. Deliberate injection of aerosol particles into the stratosphere is a potential climate engineering scheme. Introduction of particles into the stratosphere would scatter solar radiation back to space, thereby reducing the temperature at the Earth’s surface and hence the impacts of global warming. Minerals such as TiO2 or SiO2 are among the potentially suitable aerosol materials for stratospheric particle injection due to their greater light scattering ability compared to stratospheric sulfuric acid particles. However, the heterogeneous reactivity of mineral particles towards trace gases important for stratospheric chemistry largely remains unknown, precluding reliable assessment of their impacts on stratospheric ozone which is of key environmental significance. In this work we have investigated for the first time the heterogeneous hydrolysis of ClONO2 on TiO2 and SiO2 aerosol particles at room temperature and at different relative humidities (RH), using an aerosol flow tube. The uptake coefficient, γ(ClONO2), on TiO2 was ~ 1.2 × 10−3 at 7 % and remaining unchanged at 33 % RH, and increased for SiO2 from ~ 2 × 10−4 at 7 % RH to ~ 5 × 10−4 at 35 % RH, reaching a value of ~ 6 × 10−4 at 59 % RH. We have also examined the impacts of a hypothetical TiO2 injection on stratospheric chemistry using the UKCA chemistry-climate model in which heterogeneous hydrolysis of N2O5 and ClONO2 on TiO2 particles is considered. A TiO2 injection scenario with a solar radiation scattering effect very similar to the eruption of Mt. Pinatubo was constructed. It is found that compared to the eruption of Mt. Pinatubo, TiO2 injection causes less ClOx activation and less ozone destruction in the lowermost stratosphere, while reduced depletion of N2O5 and NOx in the middle stratosphere results in decreased ozone levels. Overall, no significant difference in the vertically integrated ozone abundancies is found between TiO2 injection and the eruption of Mt. Pinatubo. Future work required to further assess the impacts of TiO2 injection on stratospheric chemistry is also discussed.

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 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 North Atlantic Oscillation response in GeoMIP experiments G6solar and G6sulfur: why detailed modelling is needed for understanding regional implications of solar radiation management

2020 ◽  
Author(s):  
Andy Jones ◽  
Jim M. Haywood ◽  
Anthony C. Jones ◽  
Simone Tilmes ◽  
Ben Kravitz ◽  
...  
Keyword(s):  
Solar Radiation ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Winter Season ◽  
Solar Radiation Management ◽  
Positive Anomaly ◽  
Continental Scale ◽  
Detailed Modelling ◽  
Radiation Management ◽  
The Impact

Abstract. The realisation of the difficulty of limiting global mean temperatures to within 1.5 °C or 2.0 °C above pre-industrial levels stipulated by the 21st Conference of Parties in Paris has led to increased interest in solar radiation management (SRM) techniques. Proposed SRM schemes aim to increase planetary albedo to reflect more sunlight back to space and induce a cooling that acts to partially offset global warming. Under the auspices of the Geoengineering Model Intercomparion Project, we have performed model experiments whereby global temperature under the high forcing SSP5–8.5 scenario is reduced to follow that of the medium forcing SSP2–4.5 scenario. Two different mechanisms to achieve this are employed, the first via a reduction in the solar constant (experiment G6solar) and the second via modelling injections of sulfur dioxide (experiment G6sulfur) which forms sulfate aerosol in the stratosphere. Results from two state-of-the-art coupled Earth system models both show an impact on the North Atlantic Oscillation (NAO) in G6sulfur but not in G6solar. Both models show a persistent positive anomaly in the NAO during the Northern Hemisphere winter season in G6sulfur, suggesting an increase in zonal flow and an increase in North Atlantic storm track activity impacting the Eurasian continent leading to regional warming. These findings are broadly consistent with previous findings on the impact of stratospheric volcanic aerosol on the NAO and emphasise that detailed modelling of geoengineering processes is required if accurate impacts of SRM impacts are to be simulated. Differences remain between the two models in predicting regional changes over the continental USA and Africa, suggesting that more models need to perform such simulations before attempting to draw any conclusions regarding potential continental-scale climate change under SRM.

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