Scientists: Risky schemes may be only hope for cooling planet
swift and cheap to deploy, good for biodiversity. AGAINST: Only limited potential for carbon removal, potential conflicts over land use (forests vs. food crops).
Solar radiation management
These are schemes that would cool the planet by reducing heat from the Sun rather than by curbing fossil-fuel pollution.
Some of these could have a quick cooling effect, but would not address CO2 buildup, which causes ocean acidification and other problems. They may also have a potential for causing massive environmental problems.
As a result, solar radiation management is less preferable than carbon dioxide removal, says the report. It should only be applied in an emergency and for a limited time, and in any case should accompany reductions in carbon emissions. The principal schemes:
- Albedo (reflective materials: Cover desert areas with reflecting film or generate white clouds over parts of the oceans through spray generators aboard “cloud ships.” FOR: Quick to implement and rapidly effective. AGAINST: Desert albedo would have a major impact on desert eco-systems, ocean albedo could affect weather patterns and ocean currents. Both very expensive.
- Stratospheric aerosols: Mimicking the dust spewed from volcanoes, these would be fine, white particles of sulphate that would be scattered into the stratosphere to reflect sunlight. FOR: Technically feasible, highly effective (could start to reduce temperatures within one year), can be deployed quickly and at low cost. AGAINST: Possible impact on ozone layer, high-altitude clouds, may disrupt regional rainfall patterns.
- Space sunshade: Place reflectors in orbit that would reduce the amount of solar radiation reaching Earth by one or two percent. FOR: Highly effective, and no theoretical limit on potential cooling. AGAINST: Would take decades to deploy; huge cost; potential effects on regional climate; impact of reduced sunlight on ecosystem unknown.
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