A Zero-Radiation Pressure Sunshade for Supporting Climate Change Mitigation

[Geoeng Info]

https://arxiv.org/ftp/arxiv/papers/2112/2112.13652.pdf

A Zero-Radiation Pressure Sunshade for Supporting Climate Change Mitigation

Olivia Borgue and Andreas M. Hein

Abstract 

Limiting climate change to within the 2 °C limit requires net zero emissions of CO2 by 2050. However, the window of opportunity is closing fast. Geoengineering as the intentional and large scale manipulation of the environment and in particular the climate is increasingly discussed as a complement to ongoing mitigation efforts. As a particular geoengineering approach, space-based geoengineering blocks or dissipates a fraction of incoming sunlight via many occulting membranes, located close to the Sun - Earth Lagrange 1 point. However, the mass of the proposed sunshades, around 10^7 –10^8 tons, and their cost render them about 10³ times more costly than terrestrial alternatives. In this article, we propose a novel sunshade concept, which is between 10² to 10³ times lighter than the lightest existing sunshade concepts. This is achieved via a net zero radiation pressure design, based on the use of diffractive metamaterials, removing one of the major constraints to reducing sunshade mass. The whole sunshade system has a total mass of approximately 6.2 10^5 tons and its deployment requires between 10² to 10³ annual launches during a ten-year period. The achieved cost reduction might render space-based geoengineering competitive to terrestrial geoengineering approaches.