Econ­o­mists are out of touch with cli­mate change

The Pak Banker - - OPINION - Noah Smith

IN the de­bate over cli­mate change, there is one group you don't hear much from: econ­o­mists. The fail­ure of cli­mate eco­nom­ics to make a dif­fer­ence in the pub­lic dis­cus­sion about cli­mate pol­icy should be a con­cern for the pro­fes­sion. Cli­mate econ­o­mists are just as wor­ried as any­one about the prospect of global warm­ing. A re­cent sur­vey by the In­sti­tute for Pol­icy In­tegrity found that most cli­mate econ­o­mists be­lieve cli­mate change is a grave threat. Most sup­ported car­bon taxes or cap-and-trade pro­grams to limit emis­sions, even if th­ese ac­tions were taken uni­lat­er­ally by the U.S. The con­sen­sus view was that a cat­a­strophic loss of global gross do­mes­tic prod­uct -- a 25 per­cent de­cline or more -- is pos­si­ble un­der a "busi­ness as usual" sce­nario.

But for all this con­cern, cli­mate econ re­search has had lit­tle im­pact on the pub­lic de­bate. The prob­lem, as far as I can tell, is that there is a dis­con­nect be­tween cli­mate sci­ence and eco­nom­ics. This goes be­yond the out-of­date fore­cast­ing mod­els used by pol­icy mak­ers. Even within academia, re­search of­ten uses bad sci­ence.

The first cli­mate econ pa­per I ever read pro­vides a nice il­lus­tra­tion of this prob­lem. In 2007, Michael Green­stone of the Univer­sity of Chicago and Olivier Desch­enes of the Univer­sity of Cal­i­for­nia-Santa Bar­bara pub­lished a pa­per en­ti­tled "Cli­mate Change, Mor­tal­ity, and Adap­ta­tion: Ev­i­dence from An­nual Fluc­tu­a­tions in Weather in the US." The pa­per tried to es­ti­mate how many peo­ple would die as a re­sult of global warm­ing. To do this, the au­thors cal­cu­lated how many peo­ple now die from ran­dom tem­per­a­ture fluc­tu­a­tions, due to things like heat­stroke. They then ex­trap­o­lated this ef­fect us­ing the ex­pected tem­per­a­ture in­crease from cli­mate change, and found that the prob­a­ble in­crease in mor­tal­ity is small.

But there is an ob­vi­ous prob­lem with this type of anal­y­sis, which even a se­cond-year grad stu­dent took about five sec­onds to fig­ure out. Global warm­ing will prob­a­bly kill peo­ple a lot more ways than days of ex­treme heat do now. If the cli­mate changes a lot, floods will be­come more com­mon in low-ly­ing ar­eas. Hur­ri­cane Ka­t­rina pro­vided an ex­am­ple of how a large flood can cause a lot of deaths. This has noth­ing to do with the mech­a­nism stud­ied by Desch­enes and Green­stone -- the au­thors just leave it out. If they had paid more at­ten­tion to sci­ence, they would have taken more sources of mor­tal­ity into ac­count.

This pa­per demon­strates how cli­mate eco­nom­ics can go astray. But it is far from an un­usual or soli­tary ex­am­ple. In 2011, the Stock­holm En­vi­ron­ment In­sti­tute pub­lished a re­port that chided cli­mate econ­o­mists for their fail­ure to keep up with sci­en­tific ad­vances. They glumly re­port:

Re­gret­tably, cli­mate eco­nom­ics tends to lag be­hind cli­mate sci­ence, es­pe­cially in the slow-paced, peer-re­viewed eco­nom­ics lit­er­a­ture. The analy­ses rarely por­tray the most re­cent ad­vances in cli­mate sci­ence; in­stead, they of­ten in­cor­po­rate sim­pli­fied rep­re­sen­ta­tions of sci­en­tific knowl­edge that is out of date by sev­eral years, if not decades. More­over, cli­mate eco­nom­ics has of­ten been ham­pered by its un­crit­i­cal adop­tion of a tra­di­tional cost-ben­e­fit frame­work, min­i­miz­ing or over­look­ing the deep the­o­ret­i­cal prob­lems posed by un­cer­tainty, in­ter­gen­er­a­tional im­pacts, and long-term tech­no­log­i­cal change.

The dis­con­nect be­tween eco­nom­ics and nat­u­ral sci­ence is cer­tainly part of the prob­lem. Econ­o­mists are no­to­ri­ously un­will­ing to cite re­search in other so­cial sci­ence fields, and this in­su­lar­ity -- some­times called silo­ing -prob­a­bly leads them to ig­nore the nat­u­ral sci­ences as well. But many eco­nomic phe­nom­ena are crit­i­cally de­pen­dent on nat­u­ral phe­nom­ena, so ne­glect­ing sci­ence can make econ mod­els spit out lu­di­crous re­sults. Eco­nomic mod­els, like any other, are sub­ject to the prob­lem of garbage in, garbage out.

This short­com­ing plagued a se­cond pa­per by Desch­enes and Green­stone; when they tried to es­ti­mate the im­pact of cli­mate change on agri­cul­ture, they were crit­i­cized by some of their col­leagues for us­ing out-of-date sci­ence.

The Stock­holm En­vi­ron­ment In­sti­tute re­port goes on to de­tail a num­ber of ways in which econ could im­prove by pay­ing more at­ten­tion to the lat­est sci­ence.

Newspapers in English

Newspapers from Pakistan

© PressReader. All rights reserved.