Ku wa mbere, abahanga mu bya leta ya Amerika bavuze ko gupakira ibibarafu mu nyanja ya Arctique byagabanutse kugera ku rwego rwa kabiri rwo hasi kuva aho ibyogajuru byatangiriye mu 1979.
Kugeza muri uku kwezi, rimwe gusa mu myaka 42 ishize igihanga cyakonje cyisi cyarenze kilometero kare miliyoni 4 (kilometero kare 1.5).
Arctic ishobora kubona icyi cyayo cya mbere kitagira urubura guhera mu 2035, abashakashatsi batangaje mu kwezi gushize mu kinyamakuru Nature Climate Change.
Ariko ibintu byose bishonga urubura na barafu ntibizamura urwego rwinyanja, nkuko gushonga urubura ntirisuka ikirahuri cyamazi, kibaza ikibazo kitoroshye: Ninde ubitayeho?
Tuvugishije ukuri, iyi ni inkuru mbi kubidubu, nkuko ubushakashatsi buherutse kubigaragaza, bimaze kugenda.
Nibyo, ibi rwose bivuze impinduka zimbitse z’ibinyabuzima byo mu karere, kuva phytoplankton kugera kuri baleine.
Nkuko bigaragara, hari impamvu nyinshi zo guhangayikishwa ningaruka zo kugabanuka kwurubura rwo mu nyanja ya Arctique.
Abahanga mu bya siyansi bavuga ko ahari igitekerezo cy'ibanze ari uko kugabanuka kw'ibarafu atari ikimenyetso cy'ubushyuhe bukabije ku isi, ahubwo ko ari imbaraga zibitera inyuma.
Umuhanga mu bumenyi bwa geofiziki Marco Tedesco wo mu kigo cy’isi cya kaminuza ya Columbia yabwiye AFP ati: "Gukuraho urubura rwo mu nyanja byerekana inyanja yijimye, itanga uburyo bukomeye bwo gutanga ibitekerezo."
Ariko iyo indorerwamo yasimbujwe amazi yubururu bwijimye, hafi ijanisha rimwe ryingufu zumuriro wisi.
Ntabwo tuvuga agace kashe hano: itandukaniro riri hagati yikigereranyo cya barafu byibuze kuva 1979 kugeza 1990 nu mwanya wo hasi wanditswe uyumunsi ni kilometero kare miliyoni 3 - inshuro ebyiri zubufaransa, Ubudage na Espagne hamwe.
Inyanja imaze gukuramo 90 ku ijana by'ubushyuhe burenze urugero buterwa na gaze ya parike ya antropogeneque, ariko ibi biza ku giciro, harimo impinduka z’imiti, ubushyuhe bwinshi bwo mu nyanja hamwe n’ibiti bya korali bipfa.
Imihindagurikire y’ikirere ku isi ikubiyemo imigezi yo mu nyanja ihuza imiyoboro itwarwa n’umuyaga, imivumba, hamwe n’icyo bita kuzenguruka kwa termohaline, ubwayo iterwa n’imihindagurikire y’ubushyuhe (“ubushyuhe”) hamwe n’umunyu mwinshi (“brine”).
Ndetse impinduka ntoya mumukandara wa convoyeur (inyura hagati yinkingi ikazenguruka inyanja uko ari itatu) irashobora kugira ingaruka mbi kubihe.
Kurugero, hashize imyaka igera ku 13.000, mugihe Isi yavuye mugihe cyibarafu ikajya mubihe bitandukanye byemerera amoko yacu gutera imbere, ubushyuhe bwisi bwagabanutseho dogere selisiyusi nkeya.
Ibimenyetso bya geologiya byerekana ko umuvuduko mukuzunguruka kwa termohaline uterwa n’amazi menshi kandi yihuse y’amazi meza akonje aturuka muri Arctique.
Umushakashatsi Xavier Fettweiss wo muri kaminuza ya Liege mu Bubiligi yagize ati: "Amazi meza ava mu nyanja no ku butaka muri Greenland bihungabanya kandi bigabanya umugezi w'ikigobe."
Ati: “Niyo mpamvu Uburayi bw’iburengerazuba bufite ikirere cyoroheje kurusha Amerika ya Ruguru ku burebure bumwe.”
Urubura runini ku butaka muri Greenland rwatakaje toni zirenga miliyari 500 z'amazi meza umwaka ushize, yose yamenetse mu nyanja.
Umubare w'ibyanditswe biterwa ahanini n'ubushyuhe bwiyongera, buzamuka ku gipimo cya kabiri muri Arctique kurusha isi yose.
Fettwiss yatangarije AFP ati: "Ubushakashatsi bwinshi bwerekanye ko kwiyongera k'uburebure bwo mu mpeshyi ya Arctique biterwa ahanini n'uburebure bwa barafu yo mu nyanja."
Nk’uko ubushakashatsi bwasohotse mu kinyamakuru Nature muri Nyakanga bubitangaza, inzira y’imihindagurikire y’ikirere ndetse n’itangira ry’impeshyi itagira urubura, nkuko byasobanuwe n’akanama gashinzwe umutekano ku isi k’umuryango w’abibumbye gashinzwe imihindagurikire y’ibihe, kari munsi ya kilometero kare miliyoni.mu mpera z'ikinyejana, idubu izicwa n'inzara.
Umwanditsi mukuru w’ubushakashatsi, Stephen Armstrup, umuhanga mu bya siyanse muri Polar Bears International, yatangarije AFP ati: "Ubushyuhe bukabije bw’abantu busobanura ko ubuvumo bw’inyanja bugira urubura rwo mu nyanja kandi ruto."