Mixed phase regime cloud thinning over the polar oceans during winter

Atmosphere / solar radiation

Clouds play an important role in the Earth’s energy system. The effects of clouds are complex and diverse, often having simultaneous cooling and warming effects. Mixed-phase clouds (MPC) are clouds that contain water vapor, ice particles, and supercooled water droplets. MPCs are still poorly understood and 'notoriously difficult to represent in numerical weather prediction and climate models' (Korolev et al. 2017).

Villanueva et al. (2022) suggest that mixed-phase cloud thinning (MCT) could be a potential alternative cloud seeding measure alongside marine cloud brightening (MCB) and cirrus cloud thinning (CCT). The idea of MCT would be to thin MPCs during winter by seeding them. The effect of this thinning would likely be to reduce the capacity of clouds to trap heat and to reflect solar radiation (Villanueva et al. 2022).

Technological Readiness Level (TRL)

Low 1

This measure has only been suggested recently and has apparently not been explored since. As described elsewhere in this report, cloud seeding is already being done around the world. This might mean MCT could rely on already developed technologies.

Technological Readiness Level (TRL)

A technology with a TRL of 1-3: TRL 1 – Basic; TRL 2 – Concept formulated; TRL 3 – Experimental proof of concept

Scalability

Unknown 0

Timeliness for near-future effects

Unknown 0

Northern + Arctic potential

Unknown 0

Villanueva et al (2022) found a significant net positive cooling effect for their Arctic model scenario, with temperature decreases of roughly 0.5 to 0.1 degree C over the Arctic Ocean, and an increase in winter sea ice extent. In contrast to CCT, they also did not find a risk of adverse effects due to overseeding.

Global potential

Unknown 0

Cost - benefit

Unknown 0

Environmental risks

Unknown 0

Villanueva et al (2022) found a slight reduction in global precipitation rates in their model study.

Community impacts

Unknown 0

Ease of reversibility

Unknown 0

Villanueva et al (2022) state that MCT seeding aerosols have shorter lifetimes than in SAI, allowing for a more rapid reversal.

Risk of termination shock

Unknown 0

Legality/governance

Medium 2

Cloud seeding is already frequently done to enhance precipitation (see Cloud seeding). Such seeding falls under national or local legislative and governance structures, and MCT could potentially be considered similarly. However difficulties emerge with regards to deployment over the High Seas.

Legality/governance

Fits within existing structures to a certain degree, but some policy changes are needed to deploy at scale

Scientific/media attention

Low 1

This measure has only been suggested recently, and not received any substantial coverage.

Scientific/media attention

Very low attention from individuals and/or abandoned ideas; low media attention; no commercial interest.

References

Korolev, A., McFarquhar, G., Field, P. R., Franklin, C., Lawson, P., Wang, Z., ... & Wendisch, M. (2017). Mixed-phase clouds: Progress and challenges. Meteorological Monographs, 58, 5-1. https://doi.org/10.1175/AMSMONOGRAPHS-D-17-0001.1

Villanueva, D., Possner, A., Neubauer, D., Gasparini, B., Lohmann, U., & Tesche, M. (2022). Mixed-phase regime cloud thinning could help restore sea ice. Environmental Research Letters, 17(11), 114057. https://doi.org/10.1088/1748-9326/aca16d

Related ideas

Ice sheets and glaciers

Stabilizing glaciers by cloud seeding

Increasing precipitation on a glacier would add to the glacier's mass, thereby directly countering the melting. Also, the snow that falls would increase glacial albedo, and thereby reduce the amount of absorbed energy.

Blue Iceberg, Rødefjord, Northeast Greenland National Park

Sea ice & icebergs

Modular iceberg creation by submersibles

In 2019, an Indonesian design team came up with the idea of a submersible device that could take in sea water, desalinate it, and then have it freeze into a solid block they called a “new ice baby” (Griffiths, 2019).

Sea ice covered Coast in July, Sterlegova, Taymyr, Russia

Sea ice & icebergs

Sea ice thickening

Sea ice thickening is an idea to slow or reverse the decline of Arctic sea ice by artificially thickening it.

Sea ice melting, North of Dickson, Taymyr, Russia

Sea ice & icebergs

Pykrete usage

Pykrete is a 6:1 mix of ice and sawdust that has the property of melting slower than regular ice. Several references have been made online to the use of pykrete as an artificial barrier, as artificial sea ice, or as blockers of moulins.

Inuit hunter traveling by snow scooter on melting sea ice, Pond Inlet, Canada

Sea ice & icebergs

Sea ice albedo modification

Apart from thickening sea ice by directly adding mass to it (see sea ice thickening), it has been suggested that the ice could also be protected by increasing its albedo and thereby reducing the amount of absorbed energy (Field et al. 2018).

Land-based measures

Reindeer herding

In many Arctic and Northern regions, domesticated or semi-domesticated reindeer (Rangifer tarandus) are the only large herbivores (Uboni et al. 2016). Reindeer play a crucial role in these ecosystems and in the livelihoods and traditions of multiple local and indigenous populations. In light of the major impact of climate change in the Arctic, the capacity of large herbivores to mitigate some of these effects is being explored. Herbivores can have different climate positive effects as they can reduce shrubification and slow ecosystem responses to climate change (Olofsson and Post 2018; Happonen et al. 2021), modify summer and winter surface albedo (te Beest et al. 2016), trample winter snow to thicken permafrost (Beer et al. 2020; Windirsch et al. 2022), and increase biomass and soil carbon sequestration (Ylänne et al. 2018; Ylänne et al. 2021; see also soil management).

Oceans & marine

Promoting ocean calcifiers to sequester atmospheric carbon

Biotic processes play an important role in oceanic carbon uptake, with most attention going to carbon-consuming photosynthesising organisms. Moore et al. (2023) argue that the potential role of shellfish and other calcifiers in carbon sequestration is significantly overlooked in the CDR literature.

Nickel Smelters, Norilsk, Siberia, Russia

Industry

Carbon capture and storage

Both emission reductions and CDR measures that actively reduce carbon dioxide are essential to reduce the amount of GHGs in the atmosphere and mitigate the effects of climate change. However, some carbon emissions, especially in the industrial and energy sectors, will be difficult to fully decarbonise.