EARTHWEEK

Houston Chronicle Sunday - - SCIENCE | ENVIRONMENT -

Trop­i­cal cy­clones

Hur­ri­cane Eu­gene at­tained Cat­e­gory 3 force in the Pa­cific off Mex­ico. • Trop­i­cal Storm Fer­nanda be­came a hur­ri­cane as it moved west­ward between Mex­ico and Hawaii.

Longevity bar­rier?

New re­search sug­gests the max­i­mum hu­man life­span could far ex­ceed the 115-year limit cited in a pre­vi­ous study, af­ter decades of in­creas­ing longevity.

Ge­neti­cist Jan Vijg of New York’s Al­bert Ein­stein Col­lege of Medicine au­thored a con­tro­ver­sial re­port last year that says hu­mans have reached our max­i­mum al­lot­ted life­span for the first time.

But other re­searchers quickly ar­gued that Vijg’s find­ings were skewed by flawed cal­cu­la­tions.

Siegfried Hekimi from Mon­treal’s McGill Univer­sity ar­gues that un­der more op­ti­mistic in­ter­pre­ta­tions of longevity data, the old­est per­son alive in 2300 would be about 150 years old.

Ex­tinc­tion alarm

Sci­en­tists say Earth’s “sixth mass ex­tinc­tion” has been un­der­way over the past cen­tury in a “bi­o­log­i­cal an­ni­hi­la­tion” that has seen bil­lions of re­gional or lo­cal pop­u­la­tions lost.

Ger­ardo Ce­bal­los of the Na­tional Au­ton­o­mous Univer­sity of Mex­ico, who led a study, said: “The sit­u­a­tion has be­come so bad it would not be eth­i­cal not to use strong lan­guage.”

He found habi­tat de­struc­tion, over­hunt­ing, pol­lu­tion, in­va­sive species and cli­mate change had caused half of the 177 mam­mal species sur­veyed to lose more than 80 per­cent of their dis­tri­bu­tion between 1900 and 2015.

Warm­ing dead­line

The world must speed up the re­duc­tion of green­house gas emis­sions within three years to cap global warm­ing be­neath the 2 de­grees Cel­sius limit agreed to in the Paris cli­mate ac­cord, ac­cord­ing to a com­men­tary in the journal Na­ture.

For­mer U.N. cli­mate chief Chris­tiana Figueres, three top cli­mate sci­en­tists and two ex­perts from busi­ness signed the let­ter just be­fore the G-20 sum­mit.

The ar­ti­cle sug­gests no new coal power plants be ap­proved af­ter 2020, along with re­new­able en­ergy sources be­ing in­creased to pro­vide at least 30 per­cent of the world’s elec­tric­ity de­mand. The burn­ing of fos­sil fu­els also should be­gin a steep de­cline, the au­thors sug­gest.

Alaskan ash

Bo­goslof volcano spewed ash high into trans-Pa­cific air routes above the Aleu­tian Is­lands dur­ing the lat­est in a se­ries of erup­tions that be­gan last De­cem­ber.

The alert level for avi­a­tion was raised to red as the ash plume reached about 30,000 feet high.

Po­lar melt

Un­prece­dented Arc­tic warmth this year vir­tu­ally en­sures the sum­mer will bring the great­est melt of the Arc­tic’s sea ice on record.

Melt­ing as of July 2 had equaled that seen in 2012, which had the low­est sea ice cov­er­age ever ob­served.

But when sci­en­tists fac­tor in the thick­ness of the re­main­ing sum­mer ice cov­er­age this month, ice vol­ume is at a record-low level, ac­cord­ing to re­searchers from the Univer­sity of Washington.

A new study finds that Arc­tic win­ter warm­ing events have be­come more fre­quent and are last­ing longer than they did three decades ago.

Earth­quakes

The cen­tral Philip­pines is­land of Leyte was jolted for the sec­ond time within a week by a pow­er­ful tem­blor.

• Earth move­ments were also felt in far south­ern New Zealand, south­ern Ja­pan, north­ern Pak­istan, south-cen­tral Alaska and east­ern Ge­or­gia.

AVO

Ash soared to a height of ap­prox­i­mately 30,000 feet above the Aleu­tians dur­ing Bo­goslof’s erup­tion.

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