Njengoba kushiwo kwezinye izikhathi, ulwandle ngeke lukhuphuke kancane kancane noma ngokuqinile njengoba isikhathi siqhubeka. Uma ukugxila kwegesi ebamba ukushisa kuqhubeka kanjena, ukukhuphuka kolwandle kanye namazinga okushisa eplanethi kuzoshesha futhi kusheshe.
Ucwaningo luye lwahlaziya ukukhula kolwandle ngokuhamba kwesikhathi futhi seluphethe ngokuthi lukhuphuke ngo-2014 ngama-50% ngokushesha kunango-1993. Yini ebangele ukuba ulwandle lukhuphuke ngokushesha okungaka?
Ukuncibilika kwamaqhwa eqhwa asezindaweni ezibandayo
Izinga lezilwandle likhuphuka ngokushesha okukhulu. Ngaphezu kwalokho, kunezindawo okuthi, ngenxa yokuba khona kwezimo zezulu ezimbi kakhulu ezifana neziphepho neziphepho ezishisayo, zidudule amanzi olwandle maphakathi nezwe futhi zishiye izindawo eziningi ezingasogwini zingakwazi ukuhlala.
Ucwaningo luthole isizathu sokuthi kungani ulwandle lukhuphuka ngokukhulu ukushesha. Imayelana nokuncibilika kweqhwa laseGreenland. Ukwanda kwamazinga okushisa aphakathi komhlaba ngenxa yokukhishwa kwegesi ebamba ukushisa okubangelwa yimisebenzi yabantu kubangela ukwanda okungama-25% kwejubane lokukhuphuka kolwandle. Eminyakeni engama-20 eyedlule, ukuncibilika kweGreenland kubange kuphela ukwanda kolwandle olungu-5%.
Lokhu kungasenza sizindle ngejubane okwenzeka ngalo imicimbi yemvelo. Sikhuluma ngeqiniso lokuthi eminyakeni engama-21 nje kuphela, ijubane lokuncibilika kweGreenland liyashesha. Kulinganiselwa ukuthi ngonyaka ka-2050, Ngeke lisaba neqhwa ehlobo eNyakatho Pole. Lokhu kungasho ukunyamalala kwezigidi zamadolobha asogwini emhlabeni wonke.
Ngo-2014, izinga lolwandle lakhuphuka cishe 3,3 mm / ngonyaka kuqhathaniswa no-2,2 mm / ngonyaka ngo-1993, kusho abaphenyi bephephabhuku i-Nature Climate Change. Lezi ziphetho zomsebenzi zibaluleke impela ngoba zenza ukubonwa okuqaphele kakhulu kokukhuphuka kolwandle esikhathini esizayo. Kulinganiselwa ukuthi ngasekupheleni kwekhulu leminyaka, kulindeleke ukuthi kube nokwanda kwamasentimitha angama-60 kuye kwangama-90.
Ukuphakama kwezinga lolwandle ubufakazi
Ubufakazi bokuthi ukuncibilika kweGreenland ne-Antarctica kuyasheshisa ukukhuphuka kwamazinga olwandle buyacindezela kakhulu futhi kuyabonakala. Ngaphezu kwalokho, iGreenland iyodwa iqukethe amanzi anele afriziwe okwenyusa izinga lolwandle ngamamitha angaba yisikhombisa, ngakho-ke ingozi yokuncibilika ngokuphelele kwalezi zinhlokomo inkulu kakhulu. Iningi lososayensi abafunda ngokuncibilika nokwenyuka kwamazinga olwandle balinganisela ukuthi ngasekupheleni kwekhulu leminyaka ngokuqinisekile lizobe selikhule ngaphezu kwemitha.
Ekuqaleni kwawo-1990, isigamu sokwanda sichazwe ngokwanda ngenxa yokufudumala, uma kuqhathaniswa neminyaka engama-30% engama-20 kamuva, ngokusho kwabaphenyi. IGreenland ineqhaza kulokhu kukhuphuka namuhla ngama-25% ngokuqhathaniswa nama-5% eminyakeni engamashumi amabili edlule. Lolu cwaningo lusize okokuqala ngqa ukuthola izindlela ezimbili ezihlukene ukuze zikwazi ukukala izinga lolwandle.
Izindlela zokulinganisa ukukhuphuka kwezinga lolwandle
Indlela yokuqala yokukala izinga lolwandle ukuhlola umnikelo kulokhu kuphakama kwezinto ezintathu: ukwanda kolwandle ngenxa yesivuvujikelele, izinguquko enanini lamanzi eligcinwe emhlabathini bese liyancibilika kusuka ezinguzungeni zeqhwa kanye neqhwa eGreenland nase-Antarctica.
Ngakolunye uhlangothi, indlela yesibili isebenzisa i-satellite altimetry. Lokhu kulinganisa ibanga phakathi kwesathelayithi nobuso bolwandle. Ngale ndlela, uma ibanga liyancipha, kungukuthi izinga lolwandle likhuphukile. Kuze kube manje, imininingwane enikezwe yi-satellite altimetry ikhombise ushintsho oluncane eminyakeni engama-20 edlule.
Njengoba ukwazi ukubona, ukukhuphuka kwamazinga olwandle kumele kufundwe ngokujulile ngoba kunezinhlekelele eziningi ezingadala ezindaweni ezisogwini nakwezomnotho emazweni amaningi.