Umfanekiso-umfanekiso
Umkhenkce waseArctic uyanyibilika, kwaye yenza njalo ngesantya esikhawulezayo kangangokuba inokuphela inyamalale kumashumi nje ambalwa eminyaka. Kwaye kukuba, njengoko isijikelezi-langa sifudumala, umaleko womkhenkce odadayo kuLwandlekazi iArctic nakwiilwandle ezingqonge loo nto awunakuqhubeka ubakho.
Kude kube ngoku siyayazi ukuba umkhenkce omncinci, oko kukuthi, umkhenkce oneminyaka nje embalwa ubudala, uyanyibilika ngokulula kwihlobo elishushu. Kodwa ngelishwa, kwakhona »umkhenkce omdala» uyanyamalala.
Imilinganiselo yomkhenkce wolwandle i-Arctic ayigqitywanga, ke abaphandi be-NASA basebenzise indlela ephuhliswe yiDyunivesithi yaseColorado (eUnited States) ebavumela ukuba babe nembono engacacanga okanye engacacanga yendlela umaleko oguquke ngayo ngumkhenkce ukusuka ngo-1984 ukuza kuthi ga ngoku , ukusukela Unokulinganisa ubushushu, ubutyuwa, ukuthungwa kunye nekhephu leyo iphumla emkhenkceni ngenxa yezixhobo zesatellite ziziimowudu.
Ke, bayila oopopayi ababonisa ukuba umkhenkce ubukhula njani kwaye ungena kwisivumelwano kule minyaka ingama-32 idlulileyo.
Akunakuze kubekho isixa somkhenkce esilinganayo. Unyaka ngamnye, iyanda ebusika kwaye iyancipha ehlotyeni. Oku kuqhelekile. Umkhenkce ophilayo ebusika uya utyeba njengoko ixesha lihamba, ukwazi ukukhula phakathi kwe-1 kunye ne-3 yeemitha kwiminyaka yokuqala, naphakathi kwe-3 kunye ne-4 yeemitha xa "sele ngumkhenkce omdala". Ezi zamva, ngenxa yoko, ziyamelana nefuthe lamaza okanye izaqhwithi; Nangona kunjalo, akukho nto ibakhusela kumaqondo obushushu anyukayo.
UWalt Meier, umphandi kwiziko le-NASA Goddard eMaryland, eUnited States, utshilo inkoliso yomkhenkce omdala ilahlekile, kwaye ndongeza:
Ngo-1980 izigaba zeminyaka emininzi zenza ngaphezulu kwama-20% e-inshorensi yomkhenkce. Namhlanje bafikelela kwi-3% kuphela.
Ukuba imeko ayitshintshi, iArctic kunokwenzeka ukuba ibe nehlobo elingena mkhenkce kungekudala.