Sci­ence un­der­mines ‘hockey-stick’ graph

The Washington Times Daily - - Opinion -

As of March 5, there have been 1,051 peer-re­viewed stud­ies rep­re­sent­ing 601 re­search in­sti­tu­tions and in­volv­ing 44 coun­tries cov­er­ing the Me­dieval Warm­ing Pe­riod (MWP) (“Slap-shot cli­mate sci­ence,” Com­men­tary, Wed­nes­day).

These stud­ies show that the MWP was global and as warm or warmer than our cur­rent tem­per­a­tures. These stud­ies ar­rived at their con­clu­sions us­ing many dif­fer­ent prox­ies for tem­per­a­ture, in­clud­ing coral, caves, pollen grains, ocean floor sed­i­ments, ice cores and di­atoms.

There is also con­firm­ing anec­do­tal ev­i­dence fur­ther strength­en­ing these stud­ies. Vik­ing burial lo­ca­tions have been found be­low the per­mafrost. An­tique vine­yards in Europe dat­ing to the pe­riod have shown up at lat­i­tudes where even to­day grapes can­not be grown. The Vik­ings were able to map the en­tire coast­line of Green­land, so it must have been close to ice-free dur­ing at least part of their stay.

Michael Mann’s hockey-stick graph, on the other hand, dis­missed en masse those stud­ies by re­duc­ing con­sid­er­ably the sig­nif­i­cance of the MWP and the sub­se­quent Lit­tle Ice Age. The graph also rel­e­gates both pe­ri­ods to no more than re­gional phe­nom­ena. Ac­cord­ing to Wil­liam Hap­per, a Prince­ton Univer­sity physi­cist, Mr. Mann’s hockey-stick graph seems to have to­tally left out Europe’s cli­mate dur­ing these two time pe­ri­ods. Had Mr. Mann treated these two pe­ri­ods as in­signif­i­cant, it likely would have brought on real prob­lems as Europe’s his­tory dur­ing that time is well­known.

Dis­re­gard­ing Mr. Mann’s study for the mo­ment, an ear­lier ques­tion arises once again: Since the MWP was at least as warm as cur­rent tem­per­a­tures, why couldn’t our cur­rent warm­ing also be just nat­u­ral vari­a­tion? There were many ear­lier pe­ri­ods dur­ing this cur­rent in­ter­glacial that were also ob­vi­ously be­cause of nat­u­ral vari­a­tion — and they were also likely warmer.

Our cur­rent warm­ing would have be­gun at the coolest point of the Lit­tle Ice Age, about 1680. But this is al­most 200 years be­fore there was any in­crease in car­bon diox­ide lev­els and long be­fore any in­dus­trial rev­o­lu­tion.

The only tem­per­a­ture in­crease we ex­pe­ri­enced into the mid-1900s ap­pears to be be­cause of nat­u­ral vari­a­tion. The 1940s to the 1970s was a cool­ing pe­riod, with warm­ing be­gin­ning again in 1975 and ex­tend­ing to about 1998. From then un­til now, tem­per­a­ture ba­si­cally has been flat de­spite car­bon-diox­ide emis­sions re­port­edly at their high­est lev­els and in­creas­ing slowly.

It is thus un­likely that Mr. Mann’s hockey- stick re­sults are valid. Mr. Mann him­self re­cently said his study is “not that im­por­tant.” The only pos­si­ble rea­son for such a com­ment would be to draw at­ten­tion away from re­sults that even Mr. Mann views as du­bi­ous. His study should be cast aside. It is highly im­prob­a­ble that 1,051 peer­re­viewed stud­ies are wrong. DENIS ABLES Vi­enna, Va.

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