Sci­en­tists: “Com­mit­ted warm­ing” can’t be stopped

The Denver Post - - NEWS - By Bruce Fin­ley

Earth rapidly is ap­proach­ing the point where the amount of warm­ing locked in by hu­man pol­lu­tion ex­ceeds the lim­its na­tions set last year at the in­ter- na­tional cli­mate meet­ing in Paris, ac­cord­ing to gov­ern­ment­backed re­search un­veiled Mon­day.

The planet faces “com­mit­ted warm­ing” by 2.7 de­grees be­fore 2100 if fos­sil fu­els are burned at cur­rent rates for another 15 years, the sci­en­tists based in Colorado and Ger­many de­ter­mined.

Even if peo­ple were able in­stantly to stop all fur­ther emis­sions of heat-trap­ping green­house gases, the tem­per­a­tures by the end of the cen­tury would in­crease by 2.3 de­grees, the sci­en­tists said in a peer-re­viewed anal­y­sis pub­lished Mon­day in the jour­nal Na­ture Cli­mate Change.

“Our work shows that there isn’t much more room for

emis­sions be­fore mak­ing those tar­gets un­achiev­able,” said Robert Pin­cus, an at­mo­spheric sci­en­tist with the Co­op­er­a­tive In­sti­tute for Re­search in En­vi­ron­men­tal Sciences, a part­ner­ship be­tween the Univer­sity of Colorado and the fed­eral Na­tional Oceanic and At­mo­spheric Ad­min­is­tra­tion.

This “com­mit­ted warm­ing” anal­y­sis in­creas­ingly is crit­i­cal be­cause it tells pol­i­cy­mak­ers around the world how long peo­ple have, given cur­rent rates of pol­lu­tion, be­fore tem­per­a­tures reach var­i­ous thresh­olds.

The re­search con­ducted by Pin­cus and at­mo­spheric sci­en­tist Thorsten Mau- rit­sen of Ger­many’s Max Planck In­sti­tute for Me­te­o­rol­ogy did not rely on com­puter model sim­u­la­tions, the ba­sis of ear­lier cli­mate change re­search. In­stead, the sci­en­tists used mea­sure­ments from the at­mos­phere and of tem­per­a­tures to cal­cu­late the ex­tent of fu­ture warm­ing. They fac­tored in the ca­pac­ity of oceans to ab­sorb car­bon pol­lu­tion. They in­cor­po­rated de­tailed data on the planet’s en­ergy im­bal­ance in which car­bon diox­ide, meth­ane and other heat-trap­ping gases build up in the at­mos­phere.

“Our es­ti­mates are based on things that have al­ready hap­pened, things we can ob­serve, and they point to the part of fu­ture warm­ing that is al­ready com­mit­ted to by past emis­sions,” Mau­rit­sen said. “Fu­ture car­bon diox­ide emis­sions will then add ex­tra warm­ing on top of that com­mit­ment.”

The find­ings sug­gest po­lit­i­cal lead­ers who hashed out the Paris agree­ment last year have fallen be­hind in ef­forts to ad­dress global warm­ing. Dur­ing those United Na­tions-backed meet­ings, lead­ers of 195 coun­tries, in­clud­ing the U.S., agreed to ac­tions to con­tain tem­per­a­ture in­creases this cen­tury to less than 3.6 de­grees above the av­er­age tem­per­a­tures in 1850. Na­tions agreed to work at lim­it­ing warm­ing to 3 de­grees.

Tem­per­a­tures since 1850 al­ready have in­creased by about 1.5 de­grees, the sci­en­tists said. They also noted that, his­tor­i­cally, hu­man emis­sions of green­house gases have in­creased ev­ery year. Even if pol­lu­tion stayed steady un­til 2053, they cal­cu­lated, there is a 50 percent chance of sur­pass­ing the Paris agree­ment tar­get of 3.6 de­grees.

The U.S. Depart­ment of En­ergy, Na­tional Sci­ence Foun­da­tion and Max Planck So­ci­ety funded the re­search be­fore Amer­i­cans elected Pres­i­dent Don­ald Trump.

Trump is try­ing to back the U.S. out of its com­mit­ments to help com­bat po­ten­tially ru­inous global warm­ing. White House of­fi­cials in June ini­ti­ated a process to with­draw from the Paris agree­ment. Trump has said the agree­ment im­poses in­tol­er­a­ble fi­nan­cial bur­dens. But other na­tions are mo­bi­liz­ing to try to re­duce pol­lu­tion and hold tem­per­a­ture in­creases to tol­er­a­ble lev­els.

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