Cli­mate change: how big a prob­lem?

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are still try­ing to pre­dict.

Theo­dosia Wade, se­nior lec­turer of bi­ol­ogy at Ox­ford Col­lege, wasn’t ini­tially con­vinced that global cli­mate change ex­isted when she first heard about it in 1988.

“We had a speaker from Emory and he was try­ing to con­vince the rest of us that global cli­mate change was a prob­lem. And I wasn’t sure,” Wade said. “I didn’t think there was enough sci­en­tific ev­i­dence to show us. I was one of the peo­ple that thought th­ese are nat­u­ral cy­cles.”

But she be­gan tak­ing a closer look at cli­mate change stud­ies in or­der to teach an en­vi­ron­men­tal science class.

What re­ally im­pressed Wade was

the data from the ini­tial re­port of the In­ter­gov­ern­men­tal Panel on Cli­mate Change in 1990, which she con­sid­ered a broad and rig­or­ous source, of ice core sam­ples show­ing the his­tor­i­cal cor­re­la­tion of car­bon diox­ide lev­els and tem­per­a­tures go­ing back 650,000 years.

“ Well, now, when the data came out show­ing car­bon diox­ide and the cor­re­la­tion, I’m like, ‘ OK, I’m con­vinced,’” she said

Signs and anec­dotes of cli­mate shifts dot the globe, from ac­tive hur­ri­cane sea­sons in the past sev­eral years to rapidly melt­ing Antarc­tic ice shelves, such as the Wilkins ice shelf which wasn’t es­ti­mated to be­gin break­ing for an­other 15 years, to changes in mi­gra­tory pat­terns of birds due to warmer weather.

But in its re­cently re­leased Fourth As­sess­ment Re­port of the IPCC, a panel of hun­dreds of sci­en­tists from around the world es­tab­lished in 1988 to ex­am­ine the sci­en­tific stud­ies, on cli­mate change, is­sued the strong­est state­ments yet on the con­di­tion of Earth’s cli­mate and mankind’s ef­fect.

Us­ing words like “ un­equiv­o­cal” and “ very likely” — terms sci­en­tists don’t use lightly — the re­port stated that the Earth is get­ting warmer and that green­house gasses gen­er­ated by hu­man ac­tiv­ity are “ very likely” ( or more than 90 per­cent prob­a­ble) the cause of the ris­ing tem­per­a­tures ex­pe­ri­enced in the last half of the 20th cen­tury.

The re­port noted the 11 hottest years on record for the last 150 years have oc­curred since 1995 and pre­dicted tem­per­a­tures would con­tinue to in­crease any­where from 2 to 4.5 de­grees Fahren­heit in the next cen­tury.

Al­though an in­crease of a few de­grees over a cen­tury may not seem like a huge dif­fer­ence to the lay per­son, the con­se­quences can be tremen­dous, said Ju­dith Curry, pro­fes­sor in the School of Earth and At­mo­spheric Sci­ences at Ge­or­gia In­sti­tute of Tech­nol­ogy.

The in­creased en­ergy in the at­mos­phere would likely bring about ex­tremes in weather, said Curry. For Ge­or­gia, that could mean more se­vere heat waves, heavy rain­fall events and more se­vere and longer droughts, such as last year’s drought and for­est fire which cost Ge­or­gia more than $ 1 bil­lion in dam­ages.

Warmer tem­per­a­tures and more hu­mid­ity also could bring more dis­eases car­ried by mos­qui­toes, such as yel­low fever and dengue.

“ In the end of the day, it’s go­ing to hit peo­ple in Ge­or­gia in the pock­et­book, if not more di­rectly by drought or hur­ri­cane or West Nile Virus,” Curry said.

Green­house gasses (GHGs), which in­clude wa­ter va­por, car­bon diox­ide, meth­ane, and ni­trous ox­ide, keep the earth at a hos­pitable tem­per­a­ture by act­ing as an in­vis­i­ble blan­ket or green­house around the earth, ex­plained Wade, al­low­ing in the sun’s rays but trap­ping some of the heat.

Nor­mally, the GHG level is reg­u­lated by a process of ex­change be­tween land, wa­ter, air and an­i­mal and plant mat­ter, but in the last sev­eral cen­turies, pri­mar­ily be­cause of burn­ing fos­sil fu­els for in­dus­try and trans­porta­tion, along with agri­cul­ture and land use changes such as de­for­esta­tion, hu­man ac­tiv­i­ties have in­tro­duced a huge amount of green­house gasses into the at­mos­phere, over­load­ing the nat­u­ral sys­tem.

From 1970 to 2004, the amount of car­bon diox­ide in the at­mos­phere in­creased by 80 per­cent, ac­cord­ing to the IPCC re­port, and the con­cen­tra­tion is now more than 380 parts per mil­lion in the at­mos­phere, or about 100 ppm more than the pre- in­dus­trial av­er­age.

The U. S., which has about five per­cent of the world’s pop­u­la­tion, pro­duced about 20 per­cent of the world’s car­bon emis­sions in 2005.

But China re­cently took the lead as top car­bon diox­ide emit­ter in 2007, ac­cord­ing to a study by the Nether­lands En­vi­ron­men­tal As­sess­ment Agency, pro­duc­ing 6.23 bil­lion met­ric tons or 7.5 per­cent more than the U. S.

But, per per­son, the U. S. still pro­duced four times as much as China.

Al­though the IPCC con­cluded global tem­per­a­tures would con­tinue to in­crease at present GHG lev­els, there’s un­cer­tainty in the de­gree and sever­ity of the in­crease, said Ju­dith Curry

Some of the un­known fac­tors in­clude eco­nomic and po­lit­i­cal sit­u­a­tions, es­pe­cially of de­vel­op­ing coun­tries like China and In­dia.

Other sources of un­cer­tainty are feed­back pro­cesses, touched off by the warmer tem­per­a­tures. One ex­am­ple is the melt­ing ice caps, which re­duce the amount of light re­flected back into space and in­creases the heat ab­sorbed by the earth, which fur­ther ac­cel­er­ates the melt­ing process.

“ Feed­backs are very com- plex,” Curry said. She pointed out there were both pos­i­tive and neg­a­tive feed­back pro­cesses that could am­plify or level them­selves out.

Dr. David Stooks­bury, state cli­ma­tol­o­gist, said while the av­er­age global cli­mate might have warmed, Ge­or­gia and the South­east re­gion has cooled, in part be­cause of the land­scape change dur­ing the last cen­tury from row crops to forests.

“ What we see on the lo­cal scale and global scale may not be in step with each other,” Stooks­bury said.

Last year’s drought was in line with Ge­or­gia’s cli­mate vari­abil­ity, said Stooks­bury, and was sim­i­lar to a drought ex­pe­ri­enced in the 1950s. He said he hadn’t fol­lowed the IPCC re­ports, but es­ti­mates that hu­man ac­tiv­ity is re­spon­si­ble for about 30 to 70 per­cent of the cli­mate change seen. Both Curry and Stooks­bury agree there needs to be more plan­ning tak­ing into ac­count cli­mate pre­dic­tions and bet­ter man­age­ment of re­sources.

To that end, Curry is help­ing to or­ga­nize a one- day “ Ge­or­gia Cli­mate Change Sum­mit” at Ge­or­gia Tech on May 6, to bring to­gether sci­en­tist, in­dus­try lead­ers and pub­lic of­fi­cials to dis­cuss cli­mate change and its pos­si­ble im­pacts on health, in­dus­try, sea lev­els and other re­lated top­ics.

“ The South­east is be­hind in deal­ing with this is­sue,” said Curry. “ One of the things we want to do with the cli­mate change sum­mit is to start peo­ple talk­ing about this.”

More in­for­ma­tion on the sum­mit is avail­able at cli­mate­sum­mit. gat­ech. edu.

To ac­cess the IPCC Fourth As­sess­ment Re­port, visit www. ipcc. ch.

The above schematic draw­ing is a rep­re­sen­ta­tion of the var­i­ous com­po­nents that af­fect cli­mate and how those com­po­nents in­ter­act.

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