Page 237 - James Rodger Fleming - Fixing the sky

powder which might perhaps be dispersed in smaller quantities than the 1 to 1 ratio
hydrogen would require. Could you or your colleagues suggest suitable agents that
might do the job with maximum efficiency consistent with the least weight? 76

Bill Malkin suggested that Wexler might wish to raise the possibility with the
country’s national defense research arm, “that serious consideration be given to
the possibility of artificially and temporarily altering (up or down) the ozone con-
77
centration over an area, as a most effective weapon.” Using the radiation model
of Syukuro Manabe and F. Möller, Wexler was able to calculate a catastrophic
o
o
80 C (144 F) stratospheric cooling that would occur with no ozone layer. 78
Seeking further advice on how to cut a “hole” in the ozone layer, Wexler
turned to chemist oliver Wulf at Caltech, who suggested that “from a purely
79
chemical viewpoint, chlorine or bromine might be a ‘deozonizer.’” Wulf and
Wexler exchanged numerous letters between December 1961 and April 1962
and met face-to-face in March, and Wulf met with Chapman in April. All these
exchanges point to the conclusion (a stunning one, given the received history
of ozone depletion) that chlorine or bromine atoms might act in a catalytic
cycle with atomic oxygen to destroy thousands of ozone molecules. For exam-
ple, Wulf wrote in early January 1962, “chlorine or bromine photosensitized
decomposition [of ozone] might come closest to a reaction in which a small
amount of added material would cause a relatively large amount of decomposi-
80
tion.” Wexler replied immediately, adding that he even had a delivery system
in mind “à la West Ford dipoles” but had “no intention of suggesting or backing
any such proposal.” 81
Wexler estimated that a 100-kiloton bromine “bomb” would destroy all ozone
in the polar regions, and four times that amount would be needed near the equa-
tor. In a handwritten note composed in January 1962 he scrawled the follow-
ing (figure 7.6):

UV decomposes o → o in presence of a halogen like Br, Cl.
3
o → o and so prevents o from forming.
3
2
o
100,000 tons Br. could theoret[ically] prevent all o north of 65 N from
3
forming.
And in another note (figure 7.7):

Br → 2 Br in sunlight destroys o → o + Bro
2
2
3
These are essentially the basis of the modern ozone-depleting chemical reactions.

220 | fearS, fantaSieS, and PoSSibilitieS of Control