These older papers appear to be of interest to geoengineers as they consider post-volcanic particulate response. By my understanding of the abstracts below, the climate response is less than expected.
Timmreck C et al. (2009) Geophys. Res. Lett. 36, doi:10.1029/2009GL040083 http://www.agu.org/pubs/crossref/2009/2009GL040083.shtml Timmreck C et al. (2010) Geophys. Res. Lett. 37, doi:10.1029/2010GL045464 http://www.agu.org/pubs/crossref/2010/2010GL045464.shtml A http://www.agu.org/pubs/crossref/2009/2009GL040083.shtml Limited temperature response to the very large AD 1258 volcanic eruption The large AD 1258 eruption had a stratospheric sulfate load approximately ten times greater than the 1991 Pinatubo eruption. Yet surface cooling was not substantially larger than for Pinatubo (∼0.4 K). We apply a comprehensive Earth System Model to demonstrate that the size of the aerosol particles needs to be included in simulations, especially to explain the climate response to large eruptions. The temperature response weakens because increased density of particles increases collision rate and therefore aerosol growth. Only aerosol particle sizes substantially larger than observed after the Pinatubo eruption yield temperature changes consistent with terrestrial Northern Hemisphere summer temperature reconstructions. These results challenge an oft-held assumption of volcanic impacts not only with respect to the immediate or longer-term temperature response, but also any ecosystem response, including extinctions. http://www.agu.org/pubs/crossref/2010/2010GL045464.shtml Aerosol size confines climate response to volcanic super-eruptions Extremely large volcanic eruptions have been linked to global climate change, biotic turnover, and, for the Younger Toba Tuff (YTT) eruption 74,000 years ago, near-extinction of modern humans. One of the largest uncertainties of the climate effects involves evolution and growth of aerosol particles. A huge atmospheric concentration of sulfate causes higher collision rates, larger particle sizes, and rapid fall out, which in turn greatly affects radiative feedbacks. We address this key process by incorporating the effects of aerosol microphysical processes into an Earth System Model. The temperature response is shorter (9–10 years) and three times weaker (−3.5 K at maximum globally) than estimated before, although cooling could still have reached −12 K in some midlatitude continental regions after one year. The smaller response, plus its geographic patchiness, suggests that most biota may have escaped threshold extinction pressures from the eruption. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
