El Nino-fu­eled CO2 spike tied to plant harm, fires

Honolulu Star-Advertiser - - NEWS - By Seth Borenstein

WASH­ING­TON >> A new NASA satel­lite has found an­other thing to blame on El Nino: A re­cent record high in­crease of car­bon diox­ide in the air.

The su­per-sized El Nino a cou­ple of years ago led to an in­crease of 3 bil­lion tons of car­bon in the air, most from trop­i­cal land ar­eas. The El Nino made it more dif­fi­cult for plants to suck up man-made car­bon emis­sions and sparked fires that re­leased more car­bon into the at­mos­phere.

The ef­fect was so large that it was the main fac­tor in the big­gest one-year jump in heat-trap­ping gas lev­els on record, NASA sci­en­tists said.

Sci­en­tists have long known that car­bon diox­ide lev­els spike dur­ing an El Nino, the nat­u­ral oc­ca­sional warm­ing of parts of the cen­tral Pa­cific that causes droughts in some places, floods in oth­ers and gen­er­ally adds to warmer tem­per­a­tures world­wide. Data from NASA’s Or­bit­ing Car­bon Ob­ser­va­tory-2, which was launched in 2014, pro­vides more specifics on how that hap­pens, by con­ti­nent. Re­searchers found that in drought-stricken parts of South Amer­ica plants grew less, there were more fires in Asia, and there was an in­creased rate of leaf de­cay in Africa. The find­ings were pub­lished Thurs­day in the jour­nal Sci­ence.

That 3 bil­lion tons of car­bon, while sig­nif­i­cant, is still dwarfed by the 10 bil­lion tons a year that comes from the burn­ing of coal, oil and gas, said Scott Den­ning, a Colorado State Univer­sity at­mo­spheric sci­en­tist. Study co-au­thor An­n­marie Elder­ing, NASA’s deputy project sci­en­tist for the satel­lite, said the new re­sults show how El Nino can coun­ter­act ef­forts to re­duce car­bon emis­sions.

Hu­man-caused car­bon diox­ide emis­sions were roughly flat in 2014, 2015 and 2016, but Na­tional Oceanic and At­mo­spheric Ad­min­is­tra­tion fig­ures show that 2015 saw a rise in car­bon in the air of 3.03 parts per mil­lion, the largest since sci­en­tists started track­ing emis­sions in Hawaii in 1959.

Nor­mally about 25 per­cent of the hu­man-caused car­bon emis­sions are sucked up by plants on land, but dur­ing this pow­er­ful El Nino that was only 5 per­cent, said Jun­jie Liu, a NASA sci­en­tist and study lead au­thor.

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