preventing the next mass extinction will require geo engineering

To find out how we’d shield our planet from sunlight, I visited the University of Oxford, winding my way through the city’s maze of pale gold spires and stone alleys to find an enclave of would-be geoengineers. Few deliberate geoengineering projects have been tried to date, but the mandate of the future-focused Oxford Martin School is to tackle scientific problems that will become important over the next century. One of its researchers is Simon Driscoll, a young geophysicist who divides his time between studying historic volcanic eruptions and figuring out how geoengineers could duplicate the effects of a volcano in the earth’s atmosphere without actually blowing anything up.

Driscoll  drew a model of the upper atmosphere on a whiteboard. “Here’s the  troposphere,” he said, drawing an arc. Above that he drew another arc  for the tropopause, which sits between the troposphere and the next arc,  the stratosphere. Most planes fly roughly in the upper troposphere,  occasionally entering the stratosphere. To cool the planet, Driscoll  explained, we’d want to inject reflective particles into the  stratosphere, because it’s too high for rain to wash them out. These  particles might remain floating in the stratosphere for up to two years,  reflecting the light and preventing the sun from heating up the lower  levels of the atmosphere, where we live. Driscoll’s passion is in  creating computer models of how the climate has responded to past  eruptions. He then uses those models to predict the outcomes of  geoengineering projects.

Harvard  physicist and public-policy professor David Keith has suggested that we  could engineer particles into tiny, thin discs with “self-levitating”  properties that could help them remain in the stratosphere for over 20  years. “There’s a lot of talk about ‘particle X,’ or the optimal  particle,” Driscoll said. “You want something that scatters light  without absorbing it.” He added that some scientists have suggested  using soot, a common volcanic byproduct, because it could be  self-levitating. The problem is that data from previous volcanic  eruptions show that soot absorbs low-wavelength light, which causes  unexpected atmospheric effects. If past eruptions like Krakatoa are any  indication—and they should be—massive soot injections would cool most of  the planet, but changes in stratospheric winds would mean that the area  over Eurasia’s valuable farmlands would get hotter. So the unintended  consequences could actually make food security much worse.

 

http://www.thedailybeast.com/newsweek/2013/05/06/the-sixth-mass-extinction-is-upon-us-can-humans-survive.html

For some strange reason wordpress disables the link below by adding some numbers to the link after the html, you need to take out the numbers, possibly in a text editor, then copy and paste the part that ends with “html”

anybody else found this problem when posting via the wordpress gadget?
http://www.thedailybeast.com/newsweek/2013/05/06/the-sixth-mass-extinction-is-upon-us-can-humans-survive.html”

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