Knowledge Gaps
Physical science / mechanism
Version published:
September 13, 2024 - 10:41pm
- More research on cirrus clouds is needed to accurately represent them in models. Currently there are conflicting results in models that depend on how models represent cirrus clouds (Gasparini et al. 2020). In particular, more observations of cirrus clouds are needed (Gasparini et al. 2020), including improved satellite retrievals and in situ aircraft or drone data. These measurements can be challenging because observing platforms may disturb the cloud environment.
- Due to model discrepancies, there is still a lot of uncertainty as to whether or not CCT would generate cooling globally or in the Arctic region (Gasparini and Lohmann 2016, Gasparini et al. 2020, Tully et al. 2023). Further model development, based on observations of cirrus clouds, is needed.
- In addition to lack of knowledge about cirrus clouds, interactions between aerosols and ice-clouds are still highly uncertain, and this uncertainty impacts the ability to assess efficacy of CCT (Tully et al. 2023). Large-eddy model studies focused on cirrus formation, evolution, and aerosol-cloud interactions would be helpful.
- Ice nucleating particles
- Mineral dust is the globally prevalent ice nucleating particle for heterogeneous nucleation of cirrus clouds, however, it is unclear what role mineral dust aerosols play in the Arctic (Tully et al. 2023).
- More research is needed into which particles would work best for seeding (Lohmann and Gasparini 2017) and the properties of the seeded particles (Gasparini et al. 2020).
- Need to determine if ice-nucleating particles used for seeding would impact lower altitude clouds (mixed-phase clouds), and whether or not that impacts effect of CCT (Gasparini et al. 2017 cited in Lohmann and Gasparini 2017, Tully et al. 2023).
- Need to determine seeding frequency (Lohmann and Gasparini 2017) and injection strategies (Gasparini et al. 2020).
- Need to determine ideal target regions (Lohmann and Gasparini 2017).
- SRM simultaneously alters top of atmosphere (TOA) and surface radiation. Global cooling or warming is mostly based on TOA effects, but Arctic/regional effects will depend a lot on the surface forcing, including sea ice melting. How can we better estimate the impacts on sea ice?
- More research on cirrus clouds is needed to accurately represent them in models. Currently there are conflicting results in models that depend on how models represent cirrus clouds (Gasparini et al. 2020). In particular, more observations of cirrus clouds are needed (Gasparini et al. 2020), including improved satellite retrievals and in situ aircraft or drone data. These measurements can be challenging because observing platforms may disturb the cloud environment.
- Due to model discrepancies, there is still a lot of uncertainty as to whether or not CCT would generate cooling globally or in the Arctic region (Gasparini and Lohmann 2016, Gasparini et al. 2020, Tully et al. 2023). Further model development, based on observations of cirrus clouds, is needed.
- In addition to lack of knowledge about cirrus clouds, interactions between aerosols and ice-clouds are still highly uncertain, and this uncertainty impacts the ability to assess efficacy of CCT (Tully et al. 2023). Large-eddy model studies focused on cirrus formation, evolution, and aerosol-cloud interactions would be helpful.
- Ice nucleating particles
- Mineral dust is the globally prevalent ice nucleating particle for heterogeneous nucleation of cirrus clouds, however, it is unclear what role mineral dust aerosols play in the Arctic (Tully et al. 2023).
- More research is needed into which particles would work best for seeding (Lohmann and Gasparini 2017) and the properties of the seeded particles (Gasparini et al. 2020).
- Need to determine if ice-nucleating particles used for seeding would impact lower altitude clouds (mixed-phase clouds), and whether or not that impacts effect of CCT (Gasparini et al. 2017 cited in Lohmann and Gasparini 2017, Tully et al. 2023).
- Need to determine seeding frequency (Lohmann and Gasparini 2017) and injection strategies (Gasparini et al. 2020).
- Need to determine ideal target regions (Lohmann and Gasparini 2017).
- SRM simultaneously alters top of atmosphere (TOA) and surface radiation. Global cooling or warming is mostly based on TOA effects, but Arctic/regional effects will depend a lot on the surface forcing, including sea ice melting. How can we better estimate the impacts on sea ice?
- More research on cirrus clouds is needed to accurately represent them in models. Currently there are conflicting results in models that depend on how models represent cirrus clouds (Gasparini et al. 2020). In particular, more observations of cirrus clouds are needed (Gasparini et al. 2020), including improved satellite retrievals and in situ aircraft or drone data. These measurements can be challenging because observing platforms may disturb the cloud environment.
- Due to model discrepancies, there is still a lot of uncertainty as to whether or not CCT would generate cooling globally or in the Arctic region (Gasparini and Lohmann 2016, Gasparini et al. 2020, Tully et al. 2023). Further model development, based on observations of cirrus clouds, is needed.
- In addition to lack of knowledge about cirrus clouds, interactions between aerosols and ice-clouds are still highly uncertain, and this uncertainty impacts the ability to assess efficacy of CCT (Tully et al. 2023). Large-eddy model studies focused on cirrus formation, evolution, and aerosol-cloud interactions would be helpful.
- Ice nucleating particles
- Mineral dust is the globally prevalent ice nucleating particle for heterogeneous nucleation of cirrus clouds, however, it is unclear what role mineral dust aerosols play in the Arctic (Tully et al. 2023).
- More research is needed into which particles would work best for seeding (Lohmann and Gasparini 2017) and the properties of the seeded particles (Gasparini et al. 2020).
- Need to determine if ice-nucleating particles used for seeding would impact lower altitude clouds (mixed-phase clouds), and whether or not that impacts effect of CCT (Gasparini et al. 2017 cited in Lohmann and Gasparini 2017, Tully et al. 2023).
- Need to determine seeding frequency (Lohmann and Gasparini 2017) and injection strategies (Gasparini et al. 2020)
- Need to determine ideal target regions (Lohmann and Gasparini 2017)
- SRM simultaneously alters top of atmosphere (TOA) and surface radiation. Global cooling or warming is mostly based on TOA effects, but Arctic/regional effects will depend a lot on the surface forcing, including sea ice melting. How can we better estimate the impacts on sea ice?
Engineering needs (technical feasibility)
Version published:
September 4, 2024 - 6:26pm
- Engineering needs have not been addressed in the scientific literature.
- Need to determine transport mechanisms for ice nucleating particles (Lohmann and Gasparini 2017). Research is needed into how to deliver seeding particles, and how the delivery mechanisms interact with clouds. Using aircraft could emit soot, with unknown interactions with cirrus clouds, but unmanned drones might be too expensive. There may also be issues with turbulence induced by aircraft leading to locally large ice supersaturations.
- Engineering needs have not been addressed in the scientific literature.
- Need to determine transport mechanisms for ice nucleating particles (Lohmann and Gasparini 2017). Research is needed into how to deliver seeding particles, and how the delivery mechanisms interact with clouds. Using aircraft could emit soot, with unknown interactions with cirrus clouds, but unmanned drones might be too expensive. There may also be issues with turbulence induced by aircraft leading to locally large ice supersaturations.
Environmental risks / benefits
Version published:
September 13, 2024 - 6:46pm
- Should we be designing CCT for a different target rather than global temperature (e.g., preserving biomes and ecoregions, preserving cold winter temperatures in temperate and polar regions)? See Zarnetske et al. (2021) for the same question raised about stratospheric aerosol injection.
- UN Sustainable Development Goals (or other biodiversity goals) could inform targets.
- Should we be designing CCT for a different target rather than global temperature (e.g., preserving biomes and ecoregions, preserving cold winter temperatures in temperate and polar regions)? See Zarnetske et al. (2021) for the same question raised about stratospheric aerosol injection.
- UN Sustainable Development Goals (or other biodiversity goals) could inform targets.
- Should we be designing CCT for a different target rather than global temperature (e.g., preserving biomes and ecoregions, preserving cold winter temperatures in temperate and polar regions)? See Zarnetske et al. (2021) for the same question raised about stratospheric aerosol injection.
- UN Sustainable Development Goals (or other biodiversity goals) could inform targets
Governance
Version published:
September 13, 2024 - 6:47pm
- Who would decide to deploy SRM (C2G 2021 Evidence Brief)?
- How much cooling might be appropriate (C2G 2021 Evidence Brief)?
- How would liability for (perceived) damages be dealt with and how might ‘losers’ be compensated (C2G 2021 Evidence Brief)?
- Can Indigenous rights and perspectives be incorporated in governance of climate solutions when solutions are implemented in the name of global environmental protection (Chuffart et al. 2023)?
- Who would decide to deploy SRM (C2G 2021 Evidence Brief)?
- How much cooling might be appropriate (C2G 2021 Evidence Brief)?
- How would liability for (perceived) damages be dealt with and how might ‘losers’ be compensated (C2G 2021 Evidence Brief)?
- Can Indigenous rights and perspectives be incorporated in governance of climate solutions when solutions are implemented in the name of global environmental protection (Chuffart et al. 2023)?
- Who would decide to deploy SRM? (C2G 2021 Evidence Brief)
- How much cooling might be appropriate? (C2G 2021 Evidence Brief)
- How would liability for (perceived) damages be dealt with and how might ‘losers’ be compensated? (C2G 2021 Evidence Brief)
- Can Indigenous rights and perspectives be incorporated in governance of climate solutions when solutions are implemented in the name of global environmental protection? (Chuffart et al. 2023)
- Who would decide to deploy SRM? (C2G 2021 Evidence Brief)
- How much cooling might be appropriate? (C2G 2021 Evidence Brief)
- How would liability for (perceived) damages be dealt with and how might ‘losers’ be compensated? (C2G 2021 Evidence Brief)
- Can Indigenous rights and perspectives be incorporated in governance of climate solutions when solutions are implemented in the name of global environmental protection? (Chuffart et al. 2023)
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