"Long before it's in the papers"
June 04, 2013

RETURN TO THE WORLD SCIENCE HOME PAGE


Climate change to go on for at least “1,000 years”

Jan. 9, 2011
Courtesy University of Calgary
and World Science staff

Ris­ing car­bon di­ox­ide lev­els in the Earth’s at­mos­phere will cause un­stop­pa­ble changes to the cli­mate for at least the next 1,000 years, a new study sug­gests.

The find­ings have led re­search­ers to es­ti­mate a col­lapse of the West Ant­arc­tic ice sheet by the year 3000, and an even­tu­al rise in the glob­al sea lev­el of at least four me­tres (yards).

At the South Pole lies the An­tar­tic Ice Sheet, shaded in red in the above di­a­gram. It is con­si­dered vu­lner­able to melt­ing due to glob­al warm­ing (Cred­it: NA­SA/GSFC Sci­en­tif­ic Vis­u­al­i­za­tion Stu­dio )


The stu­dy, to ap­pear in the Jan. 9 ad­vance on­line edi­tion of the re­search jour­nal Na­ture Ge­o­sci­ence, is billed as the first full cli­mate mod­el sim­ula­t­ion to make pre­dic­tions so far ahead. It’s based on best-case, “zero-emis­sions” sce­nar­i­os sim­ulated by sci­ent­ists from the Ca­na­di­an Cen­tre for Cli­mate Mod­el­ling and Anal­y­sis at the Uni­vers­ity of Vic­to­ria, and at the Uni­vers­ity of Cal­ga­ry, al­so in Can­a­da.

“We cre­at­ed ‘what if’ sce­nar­i­os,” said re­searcher Shawn Mar­shall of the Uni­vers­ity of Cal­ga­ry. “What if we com­pletely stopped us­ing fos­sil fu­els and put no more [car­bon di­ox­ide] in the at­mos­phere? How long would it then take to re­verse cur­rent cli­mate change trends and will things first be­come worse?” 

Ex­cess car­bon di­ox­ide emis­sions, due to the burn­ing of oil and oth­er fos­sil fu­els, are widely blamed by sci­en­tists as the main cul­prit for glob­al warm­ing.

The re­search team ex­plored zero-emis­sions sce­nar­i­os be­gin­ning in 2010 and in 2100.

The North­ern Hem­i­sphere fares bet­ter than the south in the com­put­er sim­ula­t­ions, with pat­terns of cli­mate change re­vers­ing with­in the 1,000-year time­frame in places like Can­a­da. At the same time parts of North Af­ri­ca ex­pe­ri­ence de­ser­tifica­t­ion as land dries out by up to 30 per­cent. Mean­while, ocean warm­ing of up to five de­grees Cel­sius off of Ant­arc­tica is seen as likely to trig­ger wide­spread col­lapse of the West Ant­arc­tic ice sheet.

Re­search­ers hy­poth­e­size that one rea­son for the dif­fer­ence be­tween the North and South is the slow move­ment of ocean wa­ter from the North At­lanti c in­to the South At­lanti c. “The glob­al ocean and parts of the South­ern Hem­i­sphere have much more in­er­tia, such that change oc­curs more slow­ly,” said Mar­shall. “The in­er­tia in in­ter­me­dia and deep ocean cur­rents driv­ing in­to the South­ern At­lanti c means those oceans are only now be­gin­ning to warm… [due to] emis­sions from the last cen­tu­ry. The sim­ula­t­ion showed that warm­ing will con­tin­ue rath­er than stop or re­verse on the thousand-year time scale.”

Wind cur­rents in the South­ern Hem­i­sphere may al­so have an im­pact. Mar­shall said that winds in the glob­al south tend to strength­en and stay strong with­out re­vers­ing. “This in­creases the mix­ing in the ocean, bring­ing more heat from the at­mos­phere down and warm­ing the ocean.”


* * *

Send us a comment on this story, or send it to a friend









 

Sign up for
e-newsletter
   
 
subscribe
 
cancel

On Home Page         

LATEST

  • Meet­ing on­line may lead to hap­pier mar­riages

  • Pov­erty re­duction, environ­mental safe­guards go hand in hand: UN re­port

EXCLUSIVES

  • Was black­mail essen­tial for marr­iage to evolve?

  • Plu­to has even cold­er “twin” of sim­ilar size, studies find

  • Could simple an­ger have taught people to coop­erate?

  • Diff­erent cul­tures’ mu­sic matches their spe­ech styles, study finds

MORE NEWS

  • F­rog said to de­scribe its home through song

  • Even r­ats will lend a help­ing paw: study

  • D­rug may undo aging-assoc­iated brain changes in ani­mals

The impact of rising carbon dioxide levels in the Earth’s atmosphere will cause unstoppable changes to the climate for at least the next 1,000 years, a new study suggests. The findings have led researchers to estimate a collapse of the West Antarctic ice sheet by the year 3000, and an eventual rise in the global sea level of at least four metres (yards). The study, to appear in the Jan. 9 advance online edition of the research journal Nature Geoscience, is billed as the first full climate model simulation to make predictions so far ahead. It’s based on best-case, “zero-emissions” scenarios simulated by a team of researchers from the Canadian Centre for Climate Modelling and Analysis at the University of Victoria, and at the University of Calgary, also in Canada. “We created ‘what if’ scenarios,” said researcher Shawn Marshall of the University of Calgary. “What if we completely stopped using fossil fuels and put no more [carbon dioxide] in the atmosphere? How long would it then take to reverse current climate change trends and will things first become worse?” Excess carbon dioxide emissions, due to the burning of oil and other fossil fuels, are widely blamed by scientists as the main culprit for global warming. The research team explored zero-emissions scenarios beginning in 2010 and in 2100. The Northern Hemisphere fares better than the south in the computer simulations, with patterns of climate change reversing within the 1,000-year timeframe in places like Canada. At the same time parts of North Africa experience desertification as land dries out by up to 30 percent. Meanwhile, ocean warming of up to 5°C off of Antarctica is seen as likely to trigger widespread collapse of the West Antarctic ice sheet, a region the size of the Canadian prairies. Researchers hypothesize that one reason for the difference between the North and South is the slow movement of ocean water from the North Atlantic into the South Atlantic. “The global ocean and parts of the Southern Hemisphere have much more inertia, such that change occurs more slowly,” said Marshall. “The inertia in intermediate and deep ocean currents driving into the Southern Atlantic means those oceans are only now beginning to warm… [due to] emissions from the last century. The simulation showed that warming will continue rather than stop or reverse on the thousand-year time scale.” Wind currents in the Southern Hemisphere may also have an impact. Marshall said that winds in the global south tend to strengthen and stay strong without reversing. “This increases the mixing in the ocean, bringing more heat from the atmosphere down and warming the ocean.”