Efficient formation of stratospheric aerosol for climate engineering by emission of condensible vapor from aircraft

Recent analysis suggests that the effectiveness of stratospheric aerosol climate engineering through emission of non-condensable vapors such as SO(2) is limited because the slow conversion to H(2)SO(4) tends to produce aerosol particles that are too large; SO(2) injection may be so inefficient that it is difficult to counteract the radiative forcing due to a CO(2) doubling. Here we describe an alternate method in which aerosol is formed rapidly in the plume following injection of H(2)SO(4), a condensable vapor, from an aircraft. This method gives better control of particle size and can produce larger radiative forcing with lower sulfur loadings than SO(2) injection. Relative to SO(2) injection, it may reduce some of the adverse effects of geoengineering such as radiative heating of the lower stratosphere. This method does not, however, alter the fact that such a geoengineered radiative forcing can, at best, only partially compensate for the climate changes produced by CO(2). Citation: Pierce, J. R., D. K. Weisenstein, P. Heckendorn, T. Peter, and D. W. Keith (2010), Efficient formation of stratospheric aerosol for climate engineering by emission of condensible vapor from aircraft, Geophys. Res. Lett., 37, L18805, doi: 10.1029/2010GL043975.