[ RadSafe ] Nuke exchange would shred ozone layer

[Susan Gawarecki]

Nuke exchange would shred ozone layer: study - Urban fires seen 
spreading damage
http://www.world-science.net/othernews/080407_nuke-ozone
April 7, 2008
Courtesy PNAS and World Science staff

A re­gion­al nu­clear ex­change could wipe out most of the Earth’s 
pro­tect­ive ozone lay­er, re­search­ers re­port. The lay­er is a part 
of the at­mos­phere that con­tains enough ozone to block most of the 
sun’s ul­tra­vi­o­let radia­t­ion, which burns the skin and can cause 
skin can­cer.

Mi­chael Mills of the Uni­ver­s­ity of Col­o­rado, Boul­der, and 
col­leagues con­clud­ed from sim­ula­t­ions that a con­flict in­volv­ing 
the ex­change of 100 Hiroshima-equivalent bombs would cause ur­ban fires 
whose smoke would dec­i­mate the ozone lay­er.

The fires would loft as much as five mil­lion met­ric tonnes of soot 
in­to the trop­o­sphere, the low­est at­mos­pher­ic lay­er, the 
re­search­ers ar­gued. So­lar heat­ing, they added, would then boost the 
soot in­to the strat­o­sphere, a high­er lay­er.

Up to about 60 km (40 miles) high the soot would ab­sorb so­lar 
radia­t­ion and heat the sur­round­ing gas­es, thus speed­ing up 
chem­i­cal re­ac­tions that break down ozone, the sci­en­tists said.

They used a mod­el that linked cli­mate to at­mos­pher­ic chem­is­try to 
con­duct 10-year sim­ula­t­ions. Their mod­el pre­dicts that in a 
nu­clear con­flict be­tween In­dia and Pa­ki­stan, at­mos­pher­ic 
cur­rents would likely spread soot around the globe, re­sult­ing in 
lo­cal at­mos­pher­ic warm­ing of up to 30-60 de­grees Cel­si­us.

Some ozone-destroying re­ac­tions would ac­cel­er­ate at the high­er 
tem­per­a­tures, the re­search­ers con­tin­ued. In both hemi­spheres, 
they ad­dded, the ozone from 20 de­grees north or south lat­i­tude to 
the poles would thin be­low the thresh­old de­fin­ing a cur­rently 
ex­ist­ing Ant­arc­tic ozone hole. The mod­el pre­dicts that the 
at­mos­phere would beg­in to re­cov­er in five to eight years.

The study is to ap­pear in this week’s early on­line edi­tion of the 
re­search jour­nal Pro­ceed­ings of the Na­tio­n­al Aca­de­my of Sci­en­ces.