Isikimu somhlaba wonke samanje se-thermohaline
Ukubukeza amamephu womhlaba wonke wemvula yomhlaba singabona iningi le- imvula eshisayo zenzeka enyakatho Nenkabazwe. IPalmyra Atoll, ebangeni elingu-6 degrees enyakatho, ithola cishe imvula engama-445 cm ngonyaka, kanti enye indawo, eseningizimu efanayo ne-equator, ithola u-114 cm kuphela.
Ososayensi bakholelwa ukuthi kwakuyi-quirk ye-geometry yeplanethi yomhlaba, ngoba amachibi asolwandle atshekele eceleni lapho iplanethi ijikeleza, iqhubekela phambili imvula yemvula eshisayo enyakatho ye-equator. Kepha isifundo esisha esivela eNyuvesi yaseWashington sisikhombisa ukuthi isizathu sihlobene kakhulu nemisinga yolwandle eyenziwe ezigxotsheni, izinkulungwane zamakhilomitha kude.
Lo mbhalo, ushicilelwe ngo-Okthoba 20 ngo Nature, ichaza esinye sezici eziyinhloko zesimo sezulu samaplanethi, futhi ikhombisa ukuthi amanzi aneqhwa ezigxotsheni athinta izimvula zonyaka, kubalulekile ekukhuleni kokusanhlamvu ezindaweni ezifana nesifunda sase-Sahel sase-Afrika naseningizimu yeNdiya.
Ngokuvamile, izindawo ezishisa kakhulu zinomswakama kakhulu ngoba umoya oshisayo ukhuphuka ngokushesha futhi namanzi aqukethe imvula.
Le mvula yenzeka kakhulu enyakatho Nenkabazwe ngoba ifudumele. Umbuzo uthi, yini eyenza iNyakatho Nenkabazwe ishise? Futhi kuye kwabonwa ukuthi kungenxa yokusakazwa kolwandle.
Abaqondisi balolu cwaningo (Frierson phakathi kwabanye) basebenzise izilinganiso eziningiliziwe zeziphuphutheki zeRadiant Energy System of the Earth kanye namafu eNASA (CERES), ukubona ukuthi ukukhanya kwelanga kubanga umnikelo omkhulu wokushisa eningizimu yezwe. Ngale ndlela, uma singabheka kuphela imisebe yasemkhathini, i-hemisphere eseningizimu kufanele ibe nomswakama kakhulu.
Kusetshenziswa ukubuka ukunquma ukuthuthwa kokushisa kolwandle nokusebenzisa amamodeli ekhompiyutha ukukhombisa indima esemqoka yamandla amakhulu we-thermohaline ocwila ngaseGreenland, ahamba phansi olwandle aye e-Antarctica, bese enyukela phezulu futhi akhukhuleke ngasenyakatho. Uma besingaqeda lo mkhuba, izibopho zemvula eshisayo zingahlala eningizimu yezwe.
Lokhu kungenxa yokuthi lapho amanzi ejikeleza enyakatho amashumi eminyaka ayafudumala kancane kancane, asuse amandla azungeze ama-Watts wamandla ayizigidi eziyizinkulungwane ezingama-400 asuka eningizimu yezwe aye enyakatho enqamula enkabazwe.
Sekuyiminyaka eminingi ukwehla kolwandle kube yisizathu esamukelekile se-asymmetry ezivunguvungwini ezishisayo. Kepha ngasikhathi sinye, abacwaningi abaningi abakaze bathathe le ncazelo njengevumelekile njengoba kuyimpikiswano enzima kakhulu futhi imvamisa ekuziphatheni okufana nalokhu, kunencazelo elula.
Okwamanje abazimisele njengokuzibophezela kwaziswe umphakathi jikelele kwifilimu ethi "The day after tomorrow", lapho kwakukhona khona ukuthi lo msinga ubiziwe ukusakazwa kwe-thermohaline iyeka ukubandisa iNew York. Ukunyamalala okuphelele nokungazelelwe akulindelekile njengakwifilimu, kodwa ukwehla kancane kancane kulindelekile, kubika i-United Nations futhi kulindeleke ngonyaka ka-2100, lokhu kungashintsha izimvula ezishisayo ziye eningizimu, njengoba kubonakala kukhonjiswa yirekhodi lokwakheka komhlaba okwenzekile esikhathini esedlule.
Ukwehla kwemisinga kubikezelwa ngale ndlela elandelayo: lapho kunokwanda kwezulu, amanzi ahlanzekile, futhi ukuwa eNyakatho ye-Atlantic kunganciphisa ukuminyana kwamanzi olwandle, lokhu uma kuminyene kungaba kuncane ukucwila.
Lokhu kungenye nje yobuningi bobufakazi obuye bavela eminyakeni eyi-10-15 edlule obonisa ukuthi zibaluleke kangakanani izingqimba eziphakeme emhlabeni wonke.
Imisebenzi yangaphambilini kaFrierson ikhombisa ukuthi ushintsho ebhalansi lokushisa phakathi kwama-hemispheres luyithonya kanjani imvula eshisayo. Ucwaningo lwakamuva olwenziwe nguye nabasebenzisana naye lubheka ukuthi ukungcoliswa komhlaba okuvela kwi-Industrial Revolution kwavimbela kanjani ukukhanya kwelanga enyakatho yezwe ngeminyaka yama-70 kanye nawo-80 futhi kwahlehlisa nezimvula ezishisayo zaseningizimu.
Izinguquko eziningi esikhathini esedlule bezidalwe ukungcola. Ikusasa lizoncika ekungcolisweni komoya kanye nokufudumala kwembulunga yonke, kanye nezinguquko ekujikelezeni kwezilwandle. Zonke lezi zinto zenza izimvula ezishisayo kube nzima kakhulu ukuzibikezela.
Imininingwane engaphezulu: Ukudangala kweshumi okwenzeka ezindaweni ezishisayo zesizini kusuka eGulf of Mexico, Ngabe ukufudumala kwembulunga yonke kumile unomphela?