If steps aren’t taken soon to com­bat cli­mate change, there may be no to­mor­row

The Denver Post - - OPINION -

If any­thing, the In­ter­gov­ern­men­tal Panel on Cli­mate Change (IPCC) has a habit of un­der­state­ment. The U.N. group is­sues re­ports so thor­oughly scrubbed that they seem cau­tious in the mo­ment and down­right timid in ret­ro­spect. That gives their lat­est and most dire warn­ing added force.

The new IPCC re­port ad­vises global lead­ers that the oft­cited goal of keep­ing warm­ing be­low 2 de­grees Cel­sius is riskier than many imag­ine. A 1.5­de­gree goal would be far less dan­ger­ous, but the world has only about a decade to make the “rapid and far­reach­ing” changes re­quired to meet that goal.

The dif­fer­ence be­tween 1.5 de­grees and 2 de­grees would be sub­stan­tial. Coral reefs would go from mostly gone to al­most en­tirely gone. More sea­level rise would put up to 10 mil­lion more peo­ple in dan­ger. High heat would kill more peo­ple. It would be much hot­ter on land and in cities. Deadly mos­quito­borne ill­nesses such as malaria and dengue fever would spread far­ther. Droughts would be more likely. So would del­uges. Trop­i­cal fish­eries would empty fur­ther. Sta­ple crop yields, par­tic­u­larly in some of the world’s poor­est na­tions, would de­cline more. Dis­as­trous loss of the Antarc­tic ice sheet would be more likely.

Feed­back loops could push warm­ing fur­ther than an­tic­i­pated, as, for ex­am­ple, thaw­ing per­mafrost re­leases gases the frozen ground has trapped for cen­turies. Up to nearly 1 mil­lion ad­di­tional square miles of per­mafrost would thaw at 2 de­grees of warm­ing.

The risk of ac­ti­vat­ing such a feed­back loop is one rea­son it would be so fool­ish and ir­re­spon­ sible to breach the 1.5­de­gree thresh­old. Ex­tinct species and oblit­er­ated ecosys­tems would be im­pos­si­ble to re­vive. Workarounds that do not in­volve rapidly slash­ing emis­sions — such as in­no­va­tive ways of send­ing more sun­light back into space by, for ex­am­ple, seed­ing the skies with ma­te­ri­als that re­flect so­lar ra­di­a­tion — would not stop the oceans from acid­i­fy­ing.

If fol­lowed through, the emis­sions­re­duc­tion com­mit­ments coun­tries pledged in the Paris agree­ment would help avert cat­a­strophic warm­ing. But they would still only re­strain warm­ing to 3 de­grees by the end of the cen­tury, bar­ring more am­bi­tion in the next decade and af­ter. Global green­house gas emis­sions must fall by 45 per­cent of 2010 lev­els by 2030 and de­cline sharply there­after to avoid blow­ing past 1.5 de­grees.

Yet, at the mo­ment, they con­tinue to rise.

Rad­i­cally chang­ing the tra­jec­tory would re­quire a com­bi­na­tion of strate­gies. Hu­mans would need to waste far less en­ergy. Forests would have to be pre­served and ex­panded. Emis­sions­free re­new­ables would have to ramp up — to around three­quar­ters of global elec­tric­ity de­mand by 2050 — with an as­sist from nu­clear and still­nascent car­bon­cap­ture tech­nol­ogy that se­questers emis­sions from tra­di­tional fos­sil fuel burn­ing. Ex­tra­dirty coal, which still pro­duces more elec­tric­ity than any other sin­gle source, would have to be fi­nally phased out. The tran­si­tion would re­quire in­vest­ment of about 2.5 per­cent of world GDP through 2035.

This would be dif­fi­cult but not im­pos­si­ble, if we tried. His­to­ri­ans will look in ab­so­lute as­ton­ish­ment at an Amer­i­can ad­min­is­tra­tion that not only failed to try but ac­tu­ally pushed in the wrong di­rec­tion. Mem­bers of The Den­ver Post’s ed­i­to­rial board are Me­gan Schrader, ed­i­tor of the ed­i­to­rial pages; Lee Ann Co­la­cioppo, ed­i­tor; Justin Mock, CFO; Bill Reynolds, vice pres­i­dent of cir­cu­la­tion and pro­duc­tion; Bob Kin­ney, vice pres­i­dent of in­for­ma­tion tech­nol­ogy; and TJ Hutchin­son, sys­tems ed­i­tor.

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