A climate ‘bonbon’

Depressed by the gloomy alarm of Ross Gar­naut’s revised cli­mate review? 

Glob­al tem­per­a­tures con­tin­ue to rise around the mid­points of the range of the pro­jec­tions of the Inter­gov­ern­men­tal Pan­el on Cli­mate Change (IPCC) … It is an awful real­i­ty that no major devel­op­ments inthe sci­ence hold out real­is­tic hope that the judge­ments of the 2008 Review erred in the direc­tion of over­es­ti­mat­ing the risks of cli­mate change.” Extract from Gar­naut Review, “Update Paper 5: The Sci­ence of Clmate Change”

Well… Don’t Pan­ic!™ The sky is not about to fall-in no mat­ter how much Dr Gar­naut growls. In fact, the what you find by look­ing at the data rather than at a mod­el of the data is pret­ty encour­ag­ing.

Hansen Scenario C plus Feb 2011

Here’s an updat­ed ver­sion of a pic­ture that is a favorite of mine. It shows a graph­ic from a 2006 paper by NASA’s James Hansen et. al. —the alarmist-in-chief and his crew. This paper is itself an updat­ed ver­sion of the paper [warn­ing: 5 mb] that start­ed the polit­i­cal pan­ic back in 1988. Note, espe­cial­ly, “Sce­nario C”—a cli­mate mod­el­ling pro­jec­tion lat­er adopt­ed by the UN IPCC—that describes the out­look for the emis­sions tra­jec­to­ry that Hansen and the IPCC con­sid­ered least-like­ly: emis­sions held sta­ble at year-2000 lev­els. That is, the “no warm­ing” base-case.

Over the top of the Hansen graph I’ve drawn a dot rep­re­sent­ing NASA-GISSlat­est esti­mate of glob­al tem­per­a­ture anom­alies for Feb­ru­ary, 2011: 0.44°C. You can see that this observed tem­per­a­ture falls below the pro­jec­tions made for even “Sce­nario C”. It’s been that way for a while, now, and to me it looks like stay­ing that way for a while yet. 

NOAA Land Temperatures Jan 11Here is one rea­son for my opti­mism: my plot of NOAA’s lat­est land-tem­per­a­ture anom­alies (the Feb­ru­ary down-turn is not yet reflect­ed in this data). You can eas­i­ly see the un-alarm­ing trend over the past two decades for yourself.

By the way, the “Eemi­an” peri­od ref­er­enced in Hansen’s graph­ic was the last inter-glacial peri­od, about 125,000 years ago. It was a time when tem­per­a­tures were sta­ble but some 1 — 2°C high­er than they are today. We are now prob­a­bly com­ing to the end of the cur­rent inter-glacial peri­od on earth (glacia­tion has been occur­ring every 100k years-or-so asso­ci­at­ed with the move­ment of the solar sys­tem through the galaxy). So it’s a rea­son­able speculation—briefly can­vassed in the Hansen paper—that we’re expe­ri­enc­ing a slow glob­al warm­ing toward the same lev­els as occurred dur­ing the last inter-glacial.

But that spec­u­la­tion was dis­missed by Dr Hansen on account of “the mag­ni­tude of feed­backs under BAU [‘busi­ness-as-usu­al’] warm­ing, which is far out­side the range of inter­glacial tem­per­a­tures”. He argued that man’s eco­nom­ic activ­i­ties (BAU) will result in large green­house emis­sions that will dri­ve big pos­i­tive cli­mate feed­backs, con­demn­ing the earth to much higjher lev­els of warm­ing than in the Eemi­an period. 

We’ve been wait­ing to see evi­dence of Hansen’s “feed­back” for 22 years now, with no evi­dence stronger than the imag­i­nary traces of the cli­mate models.

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