Ukufudumala Komhlaba Wonke: Izinga lokuqedwa komhlaba alibonwa eminyakeni engama-200 emachibini angaphansi kwe-arctic

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Amachibi aseCanada Subartic

Ukwehla kwezulu ngesimo seqhwa esibonwe eminyakeni yamuva ku izindawo ezingaphansi kwe-arctic ICanada iholele ekomeni okukhathazayo eLake District.

Lesi kube yisiphetho esafinyelelwa abanye abacwaningi baseLaval University, iWilfrid Laurier University, iBrock University kanye neYunivesithi yaseWaterloo ocwaningweni olushicilelwe emasontweni ambalwa edlule ekhasini elisemthethweni lephephabhuku lezesayensi iGeophysical Research Letters. Kwembula obunye ubufakazi obengeziwe, uma ngabe namanje abwenele ngokusobala kwefayela le- ukufudumala kwezwe.

Abaphenyi bafinyelele kulesi siphetho ngemuva kokufunda amachibi angama-70 ngase-Old Crow, Yukon naseChurchill, Manitoba, Canada. Iningi lamachibi afundwayo ayengaphansi kwemitha elilodwa ukujula. Ngokuya ngokuhlaziya okwenziwe, ngaphezu kwengxenye yamachibi asezindaweni ezisicaba futhi ezungezwe amahlathi, akhombisa izimpawu zokwehliswa.

Le nkinga ivela kakhulu ekunciphiseni kwamanzi kusuka ku- ncibilikisa. Isibonelo, kusuka ngo-2010 kuya ku-2012 imvula ebusika ejwayelekile e-Churchil yehle ngama-76 mm uma kuqhathaniswa nezilinganiso ezirekhodiwe phakathi kuka-1971 no-2000. Ukomiswa kwamanye amachibi, abonakala ngeso lengqondo okokuqala ngqa ngo-2010, bekungaphezu kwalokho kubizwe ngo-2013.

Kulezi zinhlobo zamachibi, imvula enjengeqhwa imele phakathi kuka-30% no-50% wamanzi anikezwa minyaka yonke. Uhlobo lokomiswa olubonwe ngabaphenyi belungakaze lubonwe eminyakeni engu-200 edlule. Ngaphezu kwalokho, ukuhlaziywa kwe-isotopic okwenziwe kumathambo e-phytoplankton aqoqwe emibhedeni yamachibi kukhombisa ukuthi amachibi alondoloze ibhalansi ye-aquifer iminyaka engama-200.

Lokhu kuzinza kwaphazamiseka ngokuzumayo eminyakeni embalwa edlule. Uma isimo sehlobo esomile nesobusika esineqhwa elincane siqhubeka, njengoba kwabikezela isimo sezulu, amachibi amaningi angajulile aseningizimu ye-arctic angagcina esome ngokuphelele. Kunzima ukubikezela yonke imiphumela yokulahleka kwale ndawo, kepha kuyiqiniso ukuthi imiphumela yemvelo ibalulekile.

I-snowmelt ingumthombo obalulekile wamanzi emachibini amaningi angaphansi kwe-arctic, kepha amamodeli wesimo sezulu abikezela ukuthi imvula enesimo seqhwa izokwehla kwezinye izindawo, kube nemiphumela ebonakalayo kwezemvelo. Kulesi sihloko, kusetshenziswa amapharamitha amathathu, njenge-isotopic data yamachibi amanzi ndawonye, ​​ama-gradients wesembozo semifino yasemhlabeni (kusuka kuvundlile ovulekile kuya emahlathini avaliwe) kanye nokukhululeka kwendawo ukukhomba amachibi asengozini yokuchithwa ngaphansi kwezimo ukugeleza kwamanzi aphansi kwe-meltwater ezindaweni ezimbili ezingaphansi kwe-arctic - I-Old Crow Plains, iYukon, ne-Hudson Bay Shoals, eManitoba, eCanada.

Amachibi atholakala emachibini angajulile nasemathafeni avulekile e-tundra akhombisa isinxephezelo esihleliwe phakathi kwezilinganiso zezinkomba ze-paleoclimatic zamachibi amanzi oksijini isotopes (δ18O) ngaphezulu kwemikhankaso eminingi yesampula, ekhishwe kuselulosi etholakala ezindaweni zokugcina zamuva zomhlaba. Lesi sinxephezelo senziwa ngukuhwamuka okukhulu okwanothisa ngo-18O okuphendula ekugelezeni kwamanzi kweqhwa okuncane kunesilinganiso eminyakeni yamuva.

Kuyaphawuleka ukuthi amachibi amaningi asondela ekufinyeleleni ekuqothulweni ngokuphelele phakathi nehlobo lonyaka we-2010, okwalandela ubusika obunemvula ephansi ngendlela yeqhwa. Ngokuya ngamarekhodi e-paleoimnological alezi zinhlobo zamachibi, izimo ezomile ngokweqile zango-2010 kungenzeka azange zenzeke eminyakeni engama-200 edlule. Lezi ziphetho ziphakamisa ukukhathazeka ukuthi ukwehla kokugeleza okusuka ekuncibilikeni kweqhwa kuzoholela ekomeni okukhulu kwamachibi angajulile kulolu hlobo lwezwe.

Ukwaziswa okwengeziwe: I-WWF ikhathazekile ngejubane namandla okuguquka kwesimo sezuluIqhwa lase-Arctic liyanyamalala ngesilinganiso serekhodiUkunyamalala okukhathazayo kweqhwa e-Arctic

 

Fuentes: Izincwadi Zokucwaninga Zezepolitiki


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