Re­searchers back up claims of over­stated cli­mate change

The Washington Times Weekly - - National - BY VA­LERIE RICHARD­SON

When­ever cli­mate mod­els over­es­ti­mate tem­per­a­tures linked to ris­ing car­bon diox­ide lev­els in the at­mos­phere, sci­en­tists have pointed to a con­ve­nient fall guy: aerosols, which cool the planet and act as a coun­ter­weight to global warm­ing.

But what if the cool­ing in­flu­ence of aerosols isn’t as pow­er­ful as be­lieved? Pre­lim­i­nary find­ings from a ma­jor study by the Uni­ver­sity of Read­ing re­leased this week have pro­vided strong cor­rob­o­ra­tion for the ar­gu­ment that widely used cli­mate mod­els are over­stat­ing the im­pact of aerosols, mean­ing that the case for man-made global warm­ing is also be­ing over­sold.

Paul “Chip” Knap­pen­berger, as­sis­tant di­rec­tor for the Cen­ter of the Study of Sci­ence at the free mar­ket Cato In­sti­tute, called the study a po­ten­tial game-changer that chal­lenges the cat­a­strophic cli­mate change nar­ra­tive.

“It un­der­cuts cli­mate alarm,” said Mr. Knap­pen­berger, who de­scribes him­self as a cli­mate “luke­warmist.” “Those cli­mate model pro­jec­tions are what’s driv­ing cli­mate pol­icy. If those are two times too high, then it just takes a lot of the wind out of the need for a rapid and dra­matic cli­mate re­sponse.”

The find­ings are likely to rekin­dle the sharp de­bate spurred by a study from Bjorn Stevens of the Max Planck In­sti­tute for Me­te­o­rol­ogy in Ham­burg, Ger­many, who pub­lished a sim­i­lar anal­y­sis in June 2015 in the Amer­i­can Me­te­o­ro­log­i­cal So­ci­ety jour­nal.

Af­ter cli­mate change skep­tics trum­peted the find­ings, Mr. Stevens is­sued a disclaimer say­ing his study did not chal­lenge hu­man­caused cli­mate change, prompt­ing a round of claims of vin­di­ca­tion from ad­vo­cates of the cli­mate change con­sen­sus.

The lat­est study was con­ducted by Ni­co­las Bel­louin, a cli­mate pro­fes­sor af­fil­i­ated with the Eu­rope-based Coper­ni­cus At­mos­phere Mon­i­tor­ing Ser­vice, who dis­cussed his find­ings in a post on the uni­ver­sity’s me­te­o­rol­ogy blog. A fi­nal re­port is ex­pected in Au­gust.

“[T]here are rea­sons to ex­pect that aerosol-cloud in­ter­ac­tions are weaker than sim­u­lated by cli­mate mod­els — and per­haps even weaker than the pre­lim­i­nary CAMS es­ti­mate,” Mr. Bel­louin said in the post.

Us­ing the Stevens data, in­de­pen­dent re­searcher Nicholas Lewis con­cluded last year that the best es­ti­mate of cli­mate sen­si­tiv­ity now falls within the range of 1.2 to 1.8 de­grees Centi­grade, a sig­nif­i­cant drop from the U.N. In­ter­gov­ern­men­tal Panel on Cli­mate Change, which has an as­sessed range of 1.5 to 4.5 de­grees Centi­grade.

Mr. Lewis and Ju­dith Curry, a cli­ma­tol­o­gist at the Georgia In­sti­tute of Tech­nol­ogy, pub­lished the find­ings in Cli­mate Dy­nam­ics in Au­gust.

“The lower the cli­mate sen­si­tiv­ity, the less fu­ture warm­ing will re­sult from our green­house gas emis­sions, the smaller any re­sul­tant im­pact, and the less the ‘need’ to ‘do some­thing’ about it,” Mr. Knap­pen­berger said in a post co-au­thored by Cato’s Pa­trick Michaels.

“Lewis’ nar­row range of un­cer­tainty in­creases our con­fi­dence that cli­mate change will not be cat­a­strophic — that is, will not pro­ceed at a rate that ex­ceeds our abil­ity to keep up,” they wrote.

Blis­ter­ing back-and-forth

The Stevens pa­per touched off a blis­ter­ing back-and-forth last year af­ter the sci­en­tist’s find­ings made the rounds in the con­ser­va­tive me­dia.

Mr. Stevens said on the Max Planck web­site that “con­trary to some re­ports that have ap­peared in the me­dia, [man-made] cli­mate change is not called into ques­tion by my study.”

“I con­tinue to be­lieve that warm­ing of Earth’s sur­face tem­per­a­tures from ris­ing con­cen­tra­tions of green­house gases car­ries risks that so­ci­ety must take se­ri­ously, even if we are lucky and (as my work seems to sug­gest) the most cat­a­strophic warm­ing sce­nar­ios are a bit less likely,” Mr. Stevens said.

The lib­eral web­site Me­dia Mat­ters for Amer­ica fol­lowed up by ac­cus­ing web­sites such as Bre­it­bart and The Daily Caller of “grossly dis­tort­ing a re­cent study on aerosols’ cli­mate im­pact,” but that is not how Mr. Knap­pen­berger sees it.

“When Bjorn Stevens put out his study, we wrote a story called ‘Death knell to cli­mate alarm,’ and it got back to Stevens, and he said, ‘Whoa, hold on a sec­ond, these guys are per­haps adding in a bunch of stuff that I didn’t ac­tu­ally say,’” Mr. Knap­pen­berger said.


Par­tic­u­lates from an in­ver­sion fill in Utah. Al­though reg­u­la­tors are warn­ing about emis­sions, a study sug­gests that the Earth’s cli­mate is less sen­si­tive than thought.

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