Geo-Engineering: tuning Earth's thermostats to cooler temperatures
Daniel Rosenfeld, The Hebrew Univ. of Jerusalem, Jerusalem, Israel
Aerosols have been observed to lower the Earth's temperature directly by reflecting solar radiation back to space or indirectly by enhancing clouds albedo and extending cloud cover, especially over ocean. The growing concern that the emissions of green house gases (GHG) drive the climate system to a state that is quickly approaching to a point of no return (e.g., committing the polar ice caps to melt, because once they start the process, a positive feedback sets in). One way to delay or avoid this is cooling the earth system artificially by dispersing aerosols.
Two main methods have been proposed:
1. Dispersing sulfate aerosols in the stratosphere, where they remain for many months and reflect effectively the solar radiation back to space, essentially mimicking the Pinatubo effect. The benefits and risks of this method will be addressed.
2. Seeding with small CCN aerosols marine stratocumulus, mimicking the effect of ship tracks. New ideas on the effectiveness of that method will be introduced.
Resorting to these methods meets objections on two grounds:
1. The concern that unexpected side effects of the seeding will induce greater problems than those that it is aimed to solve.
2. The concern that we will get addicted to that instead of biting the bullet and reducing the levels of the GHG in the atmosphere to safe levels. This will cause an increasingly unstable situation of a risk of abrupt warming without allowing any time for adaptation when the seeding will eventually stop for some reason.
These concerns will be addressed and ethical criteria will be proposed to how to deal with them.Recorded presentation
Session 1, New Mitigation Strategies to Combat Global Warming
Monday, 21 April 2008, 9:00 AM-10:00 AM, Standley I
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