I think it's worth noting that the magnitude of the feedback is small. Their order-of-magnitude estimate is -0.01 W m-2 K-1. Locally it gets larger, and the idea is very interesting, but I'm not sure how 'useful' this could be.
On Tuesday, 2 July 2013 13:12:02 UTC+1, andrewjlockley wrote: > > Poster's note : This important new result shows a useful negative > feedback, which could be enhanced by geoengineering. Potentially, terpenes > etc can be manufactured artificially and released, but more likely it would > be simpler to use genetic engineering or selective breeding to achieve this > using plants. There's also a chance that natural selection might do this > job for us, as temperatures rise, with plants that can control temperatures > naturally evolving. > > http://www.nature.com/ngeo/journal/v6/n6/abs/ngeo1800.html > > Warming-induced increase in aerosol number concentration likely to > moderate climate change > > Nature Geoscience 6, 438-442 (2013) > > doi:10.1038/ngeo1800 > > Published online 28 April 2013 > > Abstract > > Atmospheric aerosol particles influence the climate system directly by > scattering and absorbing solar radiation, and indirectly by acting as cloud > condensation nuclei. Apart from black carbon aerosol, aerosols cause a > negative radiative forcing at the top of the atmosphere and substantially > mitigate the warming caused by greenhouse gases1. In the future, tightening > of controls on anthropogenic aerosol and precursor vapour emissions to > achieve higher air quality may weaken this beneficial effect. Natural > aerosols, too, might affect future warming. Here we analyse long-term > observations of concentrations and compositions of aerosol particles and > their biogenic precursor vapours in continental mid- and high-latitude > environments. We use measurements of particle number size distribution > together with boundary layer heights derived from reanalysis data to show > that the boundary layer burden of cloud condensation nuclei increases > exponentially with temperature. Our results confirm a negative feedback > mechanism between the continental biosphere, aerosols and climate: aerosol > cooling effects are strengthened by rising biogenic organic vapour > emissions in response to warming, which in turn enhance condensation on > particles and their growth to the size of cloud condensation nuclei. This > natural growth mechanism produces roughly 50% of particles at the size of > cloud condensation nuclei across Europe. We conclude that > biosphere-atmosphere interactions are crucial for aerosol climate effects > and can significantly influence the effects of anthropogenic aerosol > emission controls, both on climate and air quality. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/groups/opt_out.
