The authors are apparently unaware that clouds act as the Earth's negative feedback cooling mechanism and have maintained relatively stable Earth temperatures for millions of years without any evidence of net positive feedback "tipping points." Not to mention, the scheme is irreversible if solar activity enters a lull such as the Maunder or Dalton minimums, and is an irreversible hazard to satellites and space travel.
Publication date: 1 April 2013 [any coincidence that this is April fool's day?]
Source:Advances in Space Research, Volume 51, Issue 7
This paper examines the concept of a Sun-pointing elliptical Earth ring comprised of dust grains to offset global warming. A new family of non-Keplerian periodic orbits, under the effects of solar radiation pressure and the Earth’s J 2 oblateness perturbation, is used to increase the lifetime of the passive cloud of particles and, thus, increase the efficiency of this geoengineering strategy. An analytical model is used to predict the orbit evolution of the dust ring due to solar-radiation pressure and the J 2 effect. The attenuation of the solar radiation can then be calculated from the ring model. In comparison to circular orbits, eccentric orbits yield a more stable environment for small grain sizes and therefore achieve higher efficiencies when the orbit decay of the material is considered. Moreover, the novel orbital dynamics experienced by high area-to-mass ratio objects, influenced by solar radiation pressure and the J 2 effect, ensure the ring will maintain a permanent heliotropic shape, with dust spending the largest portion of time on the Sun facing side of the orbit. It is envisaged that small dust grains can be released from a circular generator orbit with an initial impulse to enter an eccentric orbit with Sun-facing apogee. Finally, a lowest estimate of 1×1012 kg of material is computed as the total mass required to offset the effects of global warming.