Slim chance of dim­ming sun

Weekend Argus (Saturday Edition) - - WORLD -

OSLO: The idea of spray­ing a haze of sun-dim­ming chem­i­cals high above Earth as a quick way to slow global warm­ing faces so many ob­sta­cles it may not be fea­si­ble, a leaked draft UN re­port says.

The UN re­view of a plan­e­tary sun­shade, mim­ick­ing how a big vol­canic erup­tion can cool the planet with a veil of de­bris, is part of a broad study of cli­mate tech­nolo­gies or­dered by al­most 200 na­tions in the 2015 Paris Agree­ment.

Pro­pos­als by sci­en­tists to spray chem­i­cals high in the at­mos­phere from planes have at­tracted more at­ten­tion since Paris as a rel­a­tively cheap fix, cost­ing per­haps $1 bil­lion (R12bn) to $10bn a year.

But such geo- en­gi­neer­ing might be “eco­nom­i­cally, so­cially and in­sti­tu­tion­ally in­fea­si­ble”, ac­cord­ing to the draft on the risks of droughts, floods, heat waves and storms.

The draft, by the In­ter­gov­ern­men­tal Panel on Cli­mate Change (IPCC) about ways to limit warm­ing to 1.5°C above pre-in­dus­trial times, is due for pub­li­ca­tion in Oc­to­ber.

It could still change sub- stan­tially, the IPCC said.

Prob­lems with “so­lar ra­di­a­tion man­age­ment” in­clude test­ing and work­ing out rules for a tech­nol­ogy that could be de­ployed by a sin­gle na­tion, or even a com­pany, and might dis­rupt global weather pat­terns.

It “would re­sult in an ‘ad­dic­tion prob­lem’; once started, it’s hard to stop”, the draft says. A halt af­ter sev­eral years could lead to a jump in tem­per­a­tures be­cause green­house gases would con­tinue to build up.

David Keith, fac­ulty di­rec­tor of Har­vard Univer­sity’s so­lar geo-en­gi­neer­ing re­search pro­gramme, which is work­ing for a tiny out­door ex­per­i­ment to dim sun­shine, said there was a mis­guided “taboo” against ex­am­in­ing the tech­nol­ogy.

“We need a se­ri­ous re­search ef­fort to un­der­stand its risks and po­ten­tial ben­e­fits. Then we will be able to write in­formed as­sess­ments,” he said.

But many sci­en­tists are scep­ti­cal. “To de­ploy it safely would take many decades,” said Myles Allen, a pro­fes­sor of geosys­tem sci­ence at Ox­ford Univer­sity. – Reuters

PIC­TURE: REUTERS

A plan to weaken the sun’s im­pact on earth, to com­bat cli­mate change, might never see the light of day.

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