Ucwaningo olusha luveza ukuthi i-ice sheet yase-Antarctica yashintsha kungazelelwe eminyakeni eyisigidi edlule, lokhu okwenza ukuthi izintaba zeqhwa zibe sengozini enkulu ekushintsheni kwesimo sezulu. Lolu cwaningo, olushicilelwe kumagazini i-Nature Geoscience, lukhombisa ukuthi lapho izinga le-CO₂ lehlela ngaphansi kwama-240 ppm, ukuziphatha kweqhwa kwashintsha ngokuphelele. Kusukela ngaleso sikhathi, i-ice sheet yase-Antarctica yaba namandla okusabela ngamandla ezinguqukweni zemvelo, okungaguquki okukhulu emlandweni womhlaba. Lezi zinto zibalulekile ikakhulukazi mayelana nokwenyuka kwezinga lolwandle, okuyinkinga enkulu ezimodelini zanamuhla zesimo sezulu.
Uguquko Olungazelelwe Emlandweni Wesimo Sezulu
Lolu cwaningo lugxile esikhathini esaziwa ngokuthi i-Middle Pleistocene Transition, okwenzeka phakathi kweminyaka eyizigidi eziyi-1,2 kanye nezinkulungwane ezingama-700 edlule. Ngaphambi kwalolu shintso, imijikelezo yokubanda nokufudumala komhlaba yenzeka njalo eminyakeni engama-41 000, futhi yayilandelana ngendlela ebikezelwayo. Kodwa ngemuva kwalokho, le mijikelezo yaqala ukuthatha iminyaka engaba ngu-100 000, neziphetho ezipholileyo ezinde kakhulu. Nakuba ukuba khona kwalolu shintsho kwakwaziwa, ubufakazi obuningiliziwe ngokuthi izintaba zeqhwa zasabela kanjani ngesikhathi kusenomkhawulo wokungabikho kwamarekhodi esimo sezulu amadala kangako.
Iqhaza Lekhabhoni Diokside Ekuguquleni Isimo
Ukuze bagcwalise lesi sikhala, ithimba eliholwa ngu-Kyung-Sook Yun wase-Centre for Climate Physics eYunivesithi yase-Pusan eNingizimu Korea, basebenzise amamodeli ekhompyutha anobuchwepheshe obuphezulu. Abacwaningi bafaka idatha yezinga lokushisa nemvula emodelini ekhethekile wokulingisa ukuziphatha kwezintaba zeqhwa zase-Antarctica, okwazi ukulandela izinqubo ezinjengokugeleza, ukujiya, ukushisa ngaphakathi kanye nokusebenzisana nolwandle. Lokhu kulingisa kwadinga ukusetshenziswa kwesinye sezikhungo ezinamandla kakhulu zekhompyutha ezweni. Yilapho ososayensi bethola khona iphuzu lokuguquka elingaziwa ngaphambili: lapho ukugxila kwe-CO₂ emoyeni kwehlela ngaphansi kuka-240 ppm, i-calotte yaphayela yashintsha indlela yayo yokuphendula ngokuphelele.
Izinto Ezintathu Ezenza Ushintsho
Ngokusho kwababhali be-athikili, ushintsho aluzange lube ngokuhamba kancane kodwa lwenzeka ngokungazelelwe. Kusukela kulelo limitu le-CO₂, iqhwa laqala ukusabela ngendlela ekhuphukile ezingxenyeni zemvelo, okumelela ushintsho oluyisisekelo ekusebenzeni kwesistimu. Abacwaningi bakhomba izinto ezintathu eziyinhloko ezinikele kulokhu kuphenduka. Okokuqala, ukubanda kolwandle ngezikhathi eziqandayo, okwehle ukuncibilika kwesisekelo sezinguzunga zeqhwa. Okwesibili, ukwehla kwezinga lolwandle emhlabeni wonke, okususa umthwalo phezu koqweqwe lomhlaba, kwavumela ukuthi umhlaba ongaphansi kwe-Antarctica uphakame kancane.
Ukuphakama Kwezindawo Ezingxenyeni Zeqhwa
Lokhu kuphakama, kuhlangene namanzi abandayo, kwavuna ukunqwabelana kweqhwa ezindaweni ezingasogwini kanye nokwakheka kwezingqimba eziwugqinsi futhi ezinzile. Zonke lezi zinto ndawonye zakha isimo esisha sezulu, lapha i-ice sheet yaba nokuqina okukhulu futhi ngesikhathi esifanayo iba sengozini enkulu ekushintsheni kwezimo zemvelo. Ngokusho kososayensi, le nhlanganisela yaba nomthelela omkhulu ekuqhubeni iphuzu lokuguquka. Lokhu okutholakele, okushicilelwe ku-EurekAlert, kuqinisa umbono wokuthi izintaba zeqhwa ezinkulu zingaphendula ngendlela engeyona umugqa ezintweni ezingaphandle.
Izifundo Zamanje Nezesikhathi Esizayo
Yize izenzakalo ezihlaziyiwe zenzeka eminyakeni eyisigidi edlule, iziphetho zocwaningo zinokuhlobana okuqondile nesimo samanje. Ziqinisa ubukhona bamaphuzu okuguquka esimo sezulu, imingcele engaphezu kwayo isistimu ingashintsha ngokungazelelwe futhi ingakwazi ukubuyela emuva. Uma i-ice sheet yase-Antarctica yakwazi ukushintsha ubucayi bayo ngokuphendula ekupholiseni, nayo ingabonisa ushintsho olungazelelwe lapho kwenzeka ukufudumala komhlaba. Ngokusho kuka-Axel Timmermann, umbhali osebenzisana nabo, ucwaningo lukhombisa ukuthi iqhwa lase-Antarctica lingaphendula ngamandla amakhulu ezintweni ezingaphandle kunalokho okwakucatshangwa ngaphambili, okusikisela ukuthi ezinye izilinganiso zingase zingakwazi ukuthwebula ngokugcwele ushintsho olusheshayo kusistimu.
I-Antarctica ithathwa njengomthombo omkhulu wokungaqiniseki ezilinganisweni zokwenyuka kwezinga lolwandle kuleli khulu leminyaka. Ngakho-ke, ukuqonda izindlela zokuphendula kwe-ice sheet kubalulekile ekuthuthukiseni amamodeli esimo sezulu. Umthelela omkhulu walolu cwaningo ukuhlinzeka ubufakazi bokuthi iqhwa selike lwephula umkhawulo obalulekile esikhathini esedlule. Ngokuthola leli phuzu lokuguquka, ososayensi bathola ithuluzi elisha lokucubungula izibikezelo mayelana nekusasa lezindawo ezingasogwini emhlabeni ofudumalayo.