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ukuguquguquka kobunjalozwe — isiZulu
Lokhu kusho ukuquguka kwesimo sezulu esijwayelekile, okukhudlwana impela, okwenzeka endaweni ethile noma ezindaweni ezithile. Kusukela ekudalweni kohlelo lomkhathi womhlaba (Earth-atmosphere system) eminyakeni eyizigidi eziyizi-4 500 eyadlula kulokhu kuguquke njalo ukwakheka komkhathi. Ubufakazi bezimo zezulu zasemandulo buyabonakala emadwaleni akhe ungqimba lomhlaba (Earth’s crust). Amarekhodi amadwala ayabonisa ukuthi kwaguquka kakhulu ukwakheka komkhathi emva kokuvela kwezinto eziphilayo eminyakeni eyizigidi eziyizi-2 300 eyadlula. Ubunjalozwe obujwayelekile esibubonayo kulezi zinsuku buyingxenye yakamuva nje yemvelo yomhlaba; empeleni, lesi simo sineminyaka yobudala engekho ngaphezu kwezigidi ezintathu noma ezine. Kepha-ke kuleso sikhathi isimo sezulu somhlaba besilokhu siguquke njalo. Amarekhodi ejiyoloji (ukwakheka kwamadwala), isayensi yezitshalo namathambo asemandulo anamathele emadwaleni (izinsalela zamathambo nezitshalo zasemandulo) kanye nesayensi ephathelene nemivukubulo yasemandulo (izinto zobungcweti zasemandulo) abonisa ngokucacile imithelela yobunjalozwe obulokhu buguquke njalo. Ubunjalozwe buyinqubo ejwayelekile eyenzeka ngokwemvelo futhi buvamise ukwenzeka ngesivinini esincane. Ngokusebenzisa amathuluzi esimanjemanje ezobuchwepheshe sikwazile ukubona nokuhlonza izinguquko ezinohlonze ezenzeke esimweni sokwakheka komkhathi, usayizi kanye nogqinsi lwezindunduma zeqhwa emhlabeni, kanye nezinguquko ezenzekile kwizingakushisa loqobo eliqoshiwe ezindaweni ezihlukahlukene emhlabeni kule minyaka engama-50 edlule. Ngokwalezi zilinganiso, ubunjalozwe obukhona njengamanje emhlabeni bubonakala buguquka kakhulu futhi lokhu kwenzeka ngokwezinga elishaqisayo impela. Isimo sezulu somhlaba sibonisa ukushisa okungaphezulu kwezinga esilijwayele (bheka i-“global warming”). Kuyiqiniso elinobufakazi obuqanda ikhanda ukuthi umthamo wezinye zezinsalela zamakhemikhali ezithoIakala emkhathini (ikakhulukazi umthamo ophezulu wesikhutha) ulokhu ukhuphuke njalo kusukela ngeminyaka yawo-1850 (okusho ukuthi, kusukela ngesikhathi se-Industrial Revolution). Kulezi zinsuku, ziningi impela izinhlelo zamazwe ngamazwe eziqhutshwayo njengomzamo wokunqanda nokunciphisa ngenkuthalo umthamo wesikhutha esikhishwa ngabantu esingena emkhathini, kodwa-ke kuze kube manje kunongabazane mayelana nempumelelo yale mizamo. (Bheka i-“climate variability”.)
