Saturday Star - - METRO -

AL­LOW­ING the global tem­per­a­ture to tem­po­rar­ily ex­ceed or “over­shoot” 1.5ºc would mean a greater re­liance on tech­niques that re­move car­bon diox­ide from the at­mos­phere to re­turn global tem­per­a­ture to be­low 1.5°C by 2100.

“The ef­fec­tive­ness of such tech­niques are un­proven at large scale and some may carry sig­nif­i­cant risks for sus­tain­able devel­op­ment,” says the new IPCC re­port.

Its land­mark re­port cites how there are a num­ber of car­bon diox­ide re­moval meth­ods, “each with dif­fer­ent po­ten­tials for achiev­ing neg­a­tive emis­sions, as well as dif­fer­ent as­so­ci­ated costs and side ef­fects”.

One ex­am­ple in the demon­stra­tion phase is a process called Bioen­ergy with Car­bon Cap­ture and Stor­age (BECCS), in which at­mo­spheric CO² is ab­sorbed by plants and trees as they grow, and then the biomass is burned to pro­duce bioen­ergy.

“The CO² re­leased in the pro­duc­tion of bioen­ergy is cap­tured be­fore it reaches the at­mos­phere and is stored in ge­o­log­i­cal for­ma­tions deep un­der­ground on very long timescales. Since the plants ab­sorb the CO² as they grow and the process does not emit CO², the over­all ef­fect can be to re­duce at­mo­spheric CO².”

But David Hal­lowes, a lo­cal ground­work re­searcher, says: “Some of the IPCC path­ways rely on car­bon re­moval through BECCS in the sec­ond half of the cen­tury. This is a kind of sci­en­tific fairy story and the IPCC is clearly un­con­vinced by it.

“Gov­ern­ments should not make car­bon re­moval with BECCS an al­ibi for not re­duc­ing emis­sions now.

“It is par­tic­u­larly dan­ger­ous for Africa. It would re­quire grow­ing trees and other crops on vast ar­eas of land and it may be pre­dicted that the land would be grabbed from poor peo­ple in the third world.” | Sheree Bega


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