scholarly journals Solar geoengineering using solid aerosol in the stratosphere

2015 ◽  
Vol 15 (20) ◽  
pp. 11835-11859 ◽  
Author(s):  
D. K. Weisenstein ◽  
D. W. Keith ◽  
J. A. Dykema
Keyword(s):  
Radiative Forcing ◽  
Injection Rate ◽  
Sulfate Aerosols ◽  
Limited Data ◽  
Aerosol Model ◽  
Alumina Particles ◽  
Solar Geoengineering ◽  
Almost All ◽  
The Tropics ◽  
Solid Aerosol

Abstract. Solid aerosol particles have long been proposed as an alternative to sulfate aerosols for solar geoengineering. Any solid aerosol introduced into the stratosphere would be subject to coagulation with itself, producing fractal aggregates, and with the natural sulfate aerosol, producing liquid-coated solids. Solid aerosols that are coated with sulfate and/or have formed aggregates may have very different scattering properties and chemical behavior than uncoated non-aggregated monomers do. We use a two-dimensional (2-D) chemistry–transport–aerosol model to capture the dynamics of interacting solid and liquid aerosols in the stratosphere. As an example, we apply the model to the possible use of alumina and diamond particles for solar geoengineering. For 240 nm radius alumina particles, for example, an injection rate of 4 Tg yr−1 produces a global-average shortwave radiative forcing of −1.2 W m−2 and minimal self-coagulation of alumina although almost all alumina outside the tropics is coated with sulfate. For the same radiative forcing, these solid aerosols can produce less ozone loss, less stratospheric heating, and less forward scattering than sulfate aerosols do. Our results suggest that appropriately sized alumina, diamond or similar high-index particles may have less severe technology-specific risks than sulfate aerosols do. These results, particularly the ozone response, are subject to large uncertainties due to the limited data on the rate constants of reactions on the dry surfaces.

scholarly journals Solar geoengineering using solid aerosol in the stratosphere

2015 ◽  
Vol 15 (8) ◽  
pp. 11799-11851 ◽  
Author(s):  
D. K. Weisenstein ◽  
D. W. Keith
Keyword(s):  
Radiative Forcing ◽  
Transport Model ◽  
Injection Rate ◽  
Sulfate Aerosols ◽  
Limited Data ◽  
Chemical Transport Model ◽  
Solar Geoengineering ◽  
Almost All ◽  
The Tropics ◽  
Solid Aerosol

Abstract. Solid aerosol particles have long been proposed as an alternative to sulfate aerosols for solar geoengineering. Any solid aerosol introduced into the stratosphere would be subject to coagulation with itself, producing fractal aggregates, and with the natural sulfate aerosol, producing liquid-coated solids. Solid aerosols that are coated with sulfate and/or have formed aggregates may have very different scattering properties and chemical behavior than do uncoated non-aggregated monomers. We use a two-dimensional chemical transport model to capture the dynamics of interacting solid and liquid aerosols in the stratosphere. As an example, we apply the model to the possible use of alumina and diamond particles for solar geoengineering. For 240 nm radius alumina particles, for example, an injection rate of 4 Mt yr−1 produces a global-average radiative forcing of 1.3 W m−2 and minimal self-coagulation of alumina yet almost all alumina outside the tropics is coated with sulfate. For the same radiative forcing, these solid aerosols can produce less ozone loss, less stratospheric heating, and less forward scattering than do sulfate aerosols. Our results suggest that appropriately sized alumina, diamond or similar high-index particles may have less severe technology-specific risks than do sulfate aerosols. These results, particularly the ozone response, are subject to large uncertainties due the limited data on the rate constants of reactions on the dry surfaces.

scholarly journals Possible influence of anthropogenic aerosols on cirrus clouds and anthropogenic forcing

2009 ◽  
Vol 9 (3) ◽  
pp. 879-896 ◽  
Author(s):  
J. E. Penner ◽  
Y. Chen ◽  
M. Wang ◽  
X. Liu
Keyword(s):  
Biomass Burning ◽  
Radiative Forcing ◽  
Fossil Fuel ◽  
Ice Nucleation ◽  
Cirrus Clouds ◽  
Solid Particles ◽  
Sulfate Aerosols ◽  
Anthropogenic Aerosols ◽  
Upper Troposphere ◽  
Aerosol Model

Abstract. Cirrus clouds have a net warming effect on the atmosphere and cover about 30% of the Earth's area. Aerosol particles initiate ice formation in the upper troposphere through modes of action that include homogeneous freezing of solution droplets, heterogeneous nucleation on solid particles immersed in a solution, and deposition nucleation of vapor onto solid particles. Here, we examine the possible change in ice number concentration from anthropogenic soot originating from surface sources of fossil fuel and biomass burning, from anthropogenic sulfate aerosols, and from aircraft that deposit their aerosols directly in the upper troposphere. We use a version of the aerosol model that predicts sulfate number and mass concentrations in 3-modes and includes the formation of sulfate aerosol through homogeneous binary nucleation as well as a version that only predicts sulfate mass. The 3-mode version best represents the Aitken aerosol nuclei number concentrations in the upper troposphere which dominated ice crystal residues in the upper troposphere. Fossil fuel and biomass burning soot aerosols with this version exert a radiative forcing of −0.3 to −0.4 Wm−2 while anthropogenic sulfate aerosols and aircraft aerosols exert a forcing of −0.01 to 0.04 Wm−2 and −0.16 to −0.12 Wm−2, respectively, where the range represents the forcing from two parameterizations for ice nucleation. The sign of the forcing in the mass-only version of the model depends on which ice nucleation parameterization is used and can be either positive or negative. The magnitude of the forcing in cirrus clouds can be comparable to the forcing exerted by anthropogenic aerosols on warm clouds, but this forcing has not been included in past assessments of the total anthropogenic radiative forcing of climate.

scholarly journals Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

2017 ◽  
Author(s):  
Ulrike Niemeier ◽  
Hauke Schmidt
Keyword(s):  
Solar Radiation ◽  
Radiative Forcing ◽  
Transport Processes ◽  
Radiative Heating ◽  
Solar Radiation Management ◽  
Aerosol Layer ◽  
Sulfate Aerosols ◽  
Quasi Biennial Oscillation ◽  
The Tropics ◽  
Injection Rates

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. Sulfate aerosol scatters solar radiation and absorbs infrared radiation, which warms the stratospheric sulfur layer. Simulations with the general circulation model ECHAM5-HAM, including aerosol microphysics, show consequences of this warming, including changes of the quasi biennial oscillation (QBO) in the tropics. The QBO slows down after an injection of 4 Tg(S) yr−1 and completely shuts down after an injection of 8 Tg(S) yr−1. Transport of species in the tropics and sub-tropics depends on the phase of the QBO. Consequently, the heated aerosol layer not only impacts the oscillation of the QBO but also the meridional transport of the sulfate aerosols. The stronger the injection, the stronger the heating and the simulated impact on the QBO and equatorial wind systems. With increasing injection rate the velocity of the equatorial jet streams increases, and less sulfate is transported out of the tropics. This reduces the global distribution of sulfate and decreases the radiative forcing efficiency of the aerosol layer by 10 % to 14 % compared to simulations with low vertical resolution and without generated QBO. Increasing the height of the injection increases the radiative forcing only for injection rates below 10 Tg(S) yr−1 (8–10 %), a much smaller value than the 50 % calculated previously. Stronger injection rates at higher levels even result in smaller forcing than the injections at lower levels.

scholarly journals Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

2017 ◽  
Vol 17 (24) ◽  
pp. 14871-14886 ◽  
Author(s):  
Ulrike Niemeier ◽  
Hauke Schmidt
Keyword(s):  
Solar Radiation ◽  
Radiative Forcing ◽  
Transport Processes ◽  
Radiative Heating ◽  
Solar Radiation Management ◽  
Aerosol Layer ◽  
Sulfate Aerosols ◽  
Quasi Biennial Oscillation ◽  
The Tropics ◽  
Injection Rates

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. Sulfate aerosol scatters solar radiation and absorbs infrared radiation, which warms the stratospheric sulfur layer. Simulations with the general circulation model ECHAM5-HAM, including aerosol microphysics, show consequences of this warming, including changes of the quasi-biennial oscillation (QBO) in the tropics. The QBO slows down after an injection of 4 Tg(S) yr−1 and completely shuts down after an injection of 8 Tg(S) yr−1. Transport of species in the tropics and sub-tropics depends on the phase of the QBO. Consequently, the heated aerosol layer not only impacts the oscillation of the QBO but also the meridional transport of the sulfate aerosols. The stronger the injection, the stronger the heating and the simulated impact on the QBO and equatorial wind systems. With increasing injection rate the velocity of the equatorial jet streams increases, and the less sulfate is transported out of the tropics. This reduces the global distribution of sulfate and decreases the radiative forcing efficiency of the aerosol layer by 10 to 14 % compared to simulations with low vertical resolution and without generated QBO. Increasing the height of the injection increases the radiative forcing only for injection rates below 10 Tg(S) yr−1 (8–18 %), a much smaller value than the 50 % calculated previously. Stronger injection rates at higher levels even result in smaller forcing than the injections at lower levels.

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.

scholarly journals The Toba supervolcano eruption caused severe tropical stratospheric ozone depletion

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Sergey Osipov ◽  
Georgiy Stenchikov ◽  
Kostas Tsigaridis ◽  
Allegra N. LeGrande ◽  
Susanne E. Bauer ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Water Cycle ◽  
Stratospheric Ozone ◽  
System Model ◽  
Earth System ◽  
Sulfate Aerosols ◽  
Winter Conditions ◽  
Attenuation Mechanism ◽  
The Tropics ◽  
Sulfur Emissions

AbstractSupervolcano eruptions have occurred throughout Earth’s history and have major environmental impacts. These impacts are mostly associated with the attenuation of visible sunlight by stratospheric sulfate aerosols, which causes cooling and deceleration of the water cycle. Supereruptions have been assumed to cause so-called volcanic winters that act as primary evolutionary factors through ecosystem disruption and famine, however, winter conditions alone may not be sufficient to cause such disruption. Here we use Earth system model simulations to show that stratospheric sulfur emissions from the Toba supereruption 74,000 years ago caused severe stratospheric ozone loss through a radiation attenuation mechanism that only moderately depends on the emission magnitude. The Toba plume strongly inhibited oxygen photolysis, suppressing ozone formation in the tropics, where exceptionally depleted ozone conditions persisted for over a year. This effect, when combined with volcanic winter in the extra-tropics, can account for the impacts of supereruptions on ecosystems and humanity.

scholarly journals Revisiting the Agung 1963 volcanic forcing – impact of one or two eruptions

2019 ◽  
Author(s):  
Ulrike Niemeier ◽  
Claudia Timmreck ◽  
Kirstin Krüger
Keyword(s):  
Radiative Forcing ◽  
Injection Rate ◽  
Data Sets ◽  
Meridional Transport ◽  
Emission Data ◽  
Volcanic Clouds ◽  
Different Seasons ◽  
Future Emission ◽  
Volcanic Emission ◽  
The Individual

Abstract. In 1963 a series of eruptions of Mt. Agung, Indonesia, resulted in the 3rd largest eruption of the 20th century and claimed about 1900 lives. Two eruptions of this series injected SO2 into the stratosphere, a requirement to get a long lasting stratospheric sulfate layer. The first eruption on March 17th injected 4.7 Tg SO2 into the stratosphere, the second eruption 2.3 Tg SO2 on May, 16th. In recent volcanic emission data sets these eruption phases are merged together to one large eruption phase for Mt. Agung in March 1963 with an injection rate of 7 Tg SO2. The injected sulfur forms a sulfate layer in the stratosphere. The evolution of sulfur is non-linear and depends on the injection rate and aerosol background conditions. We performed ensembles of two model experiments, one with a single and a second one with two eruptions. The two smaller eruptions result in a lower burden, smaller particles and 0.1 to 0.3 Wm−2 (10–20 %) lower radiative forcing in monthly mean global average compared to the individual eruption experiment. The differences are the consequence of slightly stronger meridional transport due to different seasons of the eruptions, lower injection height of the second eruption and the resulting different aerosol evolution. The differences between the two experiments are significant but smaller than the variance of the individual ensemble means. Overall, the evolution of the volcanic clouds is different in case of two eruptions than with a single eruption only. We conclude that there is no justification to use one eruption only and both climatic eruptions should be taken into account in future emission datasets.

Improved estimates of future fire emissions under CMIP6 scenarios and implications for aerosol radiative forcing

2021 ◽  
Author(s):  
Matthew Kasoar ◽  
Douglas Hamilton ◽  
Daniela Dalmonech ◽  
Stijn Hantson ◽  
Gitta Lasslop ◽  
...  
Keyword(s):  
Machine Learning ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Learning Methods ◽  
Aerosol Radiative Forcing ◽  
Fire Emissions ◽  
Machine Learning Methods ◽  
The Tropics ◽  
In Fire ◽  
Aerosol Radiative

&lt;p&gt;The CMIP6 Shared Socioeconomic Pathway (SSP) scenarios include projections of future changes in anthropogenic biomass-burning.&amp;#160; Globally, they assume a decrease in total fire emissions over the next century under all scenarios.&amp;#160; However, fire regimes and emissions are expected to additionally change with future climate, and the methodology used to project fire emissions in the SSP scenarios is opaque.&lt;/p&gt;&lt;p&gt;We aim to provide a more traceable estimate of future fire emissions under CMIP6 scenarios and evaluate the impacts for aerosol radiative forcing. &amp;#160;We utilise interactive wildfire emissions from four independent land-surface models (CLM5, JSBACH3.2, LPJ-GUESS, and ISBA-CTRIP) used within CMIP6 ESMs, and two different machine-learning methods (a random forest, and a generalised additive model) trained on historical data, to predict year 2100 biomass-burning aerosol emissions consistent with the CMIP6-modelled climate for three different scenarios: SSP126, SSP370, and SSP585.&amp;#160; This multi-method approach provides future fire emissions integrating information from observations, projections of climate, socioeconomic parameters and changes in vegetation distribution and fuel loads.&lt;/p&gt;&lt;p&gt;Our analysis shows a robust increase in fire emissions for large areas of the extra-tropics until the end of this century for all methods.&amp;#160; Although this pattern was present to an extent in the original SSP projections, both the interactive fire models and machine-learning methods predict substantially higher increases in extra-tropical emissions in 2100 than the corresponding SSP datasets.&amp;#160; Within the tropics the signal is mixed. Increases in emissions are largely driven by the temperature changes, while in some tropical areas reductions in fire emissions are driven by human factors and changes in precipitation, with the largest reductions in Africa. The machine-learning methods show a stronger reduction in the tropics than the interactive fire models, however overall there is strong agreement between both the models and the machine-learning methods.&lt;/p&gt;&lt;p&gt;We then use additional nudged atmospheric simulations with two state-of-the-art composition-climate models, UKESM1 and CESM2, to diagnose the impact of these updated fire emissions on aerosol burden and radiative forcing, compared with the original SSP prescribed emissions.&amp;#160; We provide estimates of future fire radiative forcing, compared to modern-day, under these CMIP6 scenarios which span both the severity of climate change in 2100, and the rate of reduction of other aerosol species.&lt;/p&gt;

In vitro effectiveness of biapenem against IMP-producing Enterobacteriaceae

2021 ◽  
Vol 70 (10) ◽  
Author(s):  
Kazuyoshi Gotoh ◽  
Makoto Miyoshi ◽  
I Putu Bayu Mayura ◽  
Koji Iio ◽  
Osamu Matsushita ◽  
...  
Keyword(s):  
Therapeutic Option ◽  
Small Data ◽  
Limited Data ◽  
Data Set ◽  
Content Type ◽  
Link Type ◽  
Almost All ◽  
New Treatments ◽  
Time Kill

The options available for treating infections with carbapenemase-producing Enterobacteriaceae (CPE) are limited; with the increasing threat of these infections, new treatments are urgently needed. Biapenem (BIPM) is a carbapenem, and limited data confirming its in vitro killing effect against CPE are available. In this study, we examined the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of BIPM for 14 IMP-1-producing Enterobacteriaceae strains isolated from the Okayama region in Japan. The MICs against almost all the isolates were lower than 0.5 µg ml−1, indicating susceptibility to BIPM, while approximately half of the isolates were confirmed to be bacteriostatic to BIPM. However, initial killing to a 99.9 % reduction was observed in seven out of eight strains in a time–kill assay. Despite the small data set, we concluded that the in vitro efficacy of BIPM suggests that the drug could be a new therapeutic option against infection with IMP-producing CPE.

scholarly journals Volcanic impact on the climate – the stratospheric aerosol load in the period 2006–2015

2018 ◽  
Vol 18 (15) ◽  
pp. 11149-11169 ◽  
Author(s):  
Johan Friberg ◽  
Bengt G. Martinsson ◽  
Sandra M. Andersson ◽  
Oscar S. Sandvik
Keyword(s):  
Radiative Forcing ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Temperature Threshold ◽  
Data Set ◽  
Volcanic Impact ◽  
Almost All ◽  
Stratospheric Clouds ◽  
Correct Data

Abstract. We present a study on the stratospheric aerosol load during 2006–2015, discuss the influence from volcanism and other sources, and reconstruct an aerosol optical depth (AOD) data set in a resolution of 1∘ latitudinally and 8 days timewise. The purpose is to include the “entire” stratosphere, from the tropopause to the almost particle-free altitudes of the midstratosphere. A dynamic tropopause of 1.5 PVU was used, since it enclosed almost all of the volcanic signals in the CALIOP data set. The data were successfully cleaned from polar stratospheric clouds using a temperature threshold of 195 K. Furthermore, a method was developed to correct data when the CALIOP laser beam was strongly attenuated by volcanic aerosol, preventing a negative bias in the AOD data set. Tropospheric influence, likely from upwelling dust, was found in the extratropical transition layer in spring. Eruptions of both extratropical and tropical volcanoes that injected aerosol into the stratosphere impacted the stratospheric aerosol load for up to a year if their clouds reached lower than 20 km altitude. Deeper-reaching tropical injections rose in the tropical pipe and impacted it for several years. Our AODs mostly compare well to other long-term studies of the stratospheric AOD. Over the years 2006–2015, volcanic eruptions increased the stratospheric AOD on average by ∼40 %. In absolute numbers the stratospheric AOD and radiative forcing amounted to 0.008 and −0.2 W m−2, respectively.

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