Car­bon in at­mos­phere is ris­ing, even as emis­sions sta­bi­lize, sci­en­tists say

Tehran Times - - SCIENCE -

On the best days, the wind howl­ing across this rugged promon­tory has not touched land for thou­sands of miles, and the ar­riv­ing air seems as if it should be the clean­est in the world.

But on a cliff above the sea, in­side a low-slung gov­ern­ment build­ing, a bank of so­phis­ti­cated ma­chines sniffs that air day and night, re­veal­ing tell­tale in­di­ca­tors of the way hu­man ac­tiv­ity is al­ter­ing the planet on a ma­jor scale.

For more than two years, the mon­i­tor­ing sta­tion here, along with its coun­ter­parts across the world, has been flash­ing a warn­ing: The ex­cess car­bon diox­ide scorch­ing the planet rose at the high­est rate on record in 2015 and 2016. A slightly slower but still un­usual rate of in­crease has con­tin­ued into 2017.

Cli­mate cri­sis

Sci­en­tists are con­cerned about the cause of the rapid rises be­cause, in one of the most hope­ful signs since the global cli­mate cri­sis be­came widely un­der­stood in the 1980s, the amount of car­bon diox­ide that peo­ple are pump­ing into the air seems to have sta­bi­lized in re­cent years, at least judg­ing from the data that coun­tries com­pile on their own emis­sions.

That raises a co­nun­drum: If the amount of the gas that peo­ple are putting out has stopped ris­ing, how can the amount that stays in the air be go­ing up faster than ever? Does it mean the nat­u­ral sponges that have been ab­sorb­ing car­bon diox­ide are now chang­ing?

Sci­en­tists have spent decades mea­sur­ing what was hap­pen­ing to all of the car­bon diox­ide that was produced when peo­ple burned coal, oil and nat­u­ral gas. They es­tab­lished that less than half of the gas was re­main­ing in the at­mos­phere and warm­ing the planet. The rest was be­ing ab­sorbed by the ocean and the land sur­face, in roughly equal amounts.

Nat­u­ral sponges

In essence, th­ese nat­u­ral sponges were do­ing hu­man­ity a huge ser­vice by dis­pos­ing of much of its gaseous waste. But as emis­sions have risen higher and higher, it has been un­clear how much longer the nat­u­ral sponges will be able to keep up.

The record in­creases of air­borne car­bon diox­ide in 2015 and 2016 thus raise the ques­tion of whether this has now come to pass. Sci­en­tists are wor­ried, but they are not ready to draw that con­clu­sion, say­ing more time is needed to get a clear pic­ture.

Many of them sus­pect an El Niño cli­mate pat­tern that spanned those two years, one of the strong­est on record, may have caused the faster-than-usual rise in car­bon diox­ide, by dry­ing out large parts of the trop­ics. The dry­ing con­trib­uted to huge fires in In­done­sia in late 2015 that sent a pulse of car­bon diox­ide into the at­mos­phere. Past El Niños have also produced rapid in­creases in the gas, though not as large as the re­cent ones.

Sci­en­tists have spent decades mea­sur­ing what was hap­pen­ing to all of the car­bon diox­ide that was produced when peo­ple burned coal, oil and nat­u­ral gas.

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