The glaciation da kankara shekaru

A duk tsawon miliyoyin shekaru da suka shude tun lokacin da aka kirkiro Duniya, akwai lokutan shekarun kankara. An kira su kamar haka kankara Age. Waɗannan lokuta lokaci ne inda canjin yanayi ke faruwa wanda ke rage yawan zafin duniya. Suna yi ne ta yadda da yawa daga cikin doron duniya zasu daskare. Yana da mahimmanci a san cewa lokacin da kake magana game da canjin yanayi dole ne ka sami abin dubawa don sanya kanka a cikin yanayin duniyarmu.

Shin kana son sanin matakan glaciation da shekarun kankara na duniyar mu? Anan zamu bayyana komai.

Halaye na zamanin kankara

An bayyana shekarun kankara azaman lokaci wanda halin dindindin na babban murfin kankara yake kasancewa. Wannan kankara ta fadada zuwa akalla daya daga cikin sandunan. Duniya an san ta wuce 90% na lokacinku a cikin shekaru miliyan da suka gabata a cikin 1% na yanayin sanyi mafi sanyi. Wadannan zafin jikin su ne mafi karanci tun daga shekaru miliyan 500 da suka gabata. Watau, Duniya ta makale cikin wani yanayi mai tsananin sanyi. Wannan zamani ana kiran sa da suna Quaternary Ice Age.

Zamanin kankara huɗu da suka gabata sun faru tare da 150 miliyan shekara tazara. Saboda haka, masana kimiyya suna tunanin cewa sun faru ne saboda canje-canje a cikin falakin duniya ko canje-canjen ayyukan rana. Sauran masana kimiyya sun fi son bayanin ƙasa. Misali, bayyanar shekarun kankara yayi ishara game da rarraba nahiyoyi ko kuma yawan iskar gas.

Dangane da ma'anar glaciation, lokaci ne da ke nuna kasancewar wanzuwar kankara a sandunan sanduna. A waccan ƙa'idar ta uku, a yanzu haka mun nitse a cikin zamanin kankara, tun da iyakokin polar suka mamaye kusan 10% na duk fuskar duniya.

An fahimci annashuwa a matsayin lokacin ƙarancin kankara wanda yanayin zafin jikinsa yayi ƙasa sosai a duniya. Ganin kankara, sakamakon haka, ya miƙa zuwa ƙananan latitude kuma ya mamaye nahiyoyi. An samo kankara a cikin latitude na masarauta. Zamanin kankara na karshe ya faru kimanin shekaru dubu 11 da suka gabata.

Sanannun shekarun kankara

Akwai reshe na kimiyya wanda ke da alhakin karatun kankara. Labari ne game da kwayar halitta. Shine wanda ke kula da nazarin dukkan bayyanannun bayyananniyar ruwa a cikin yanayi mai karko. Tare da ruwa a cikin ƙaƙƙarfan yanayi suna nufin glaciers, dusar ƙanƙara, ƙanƙara, ƙanƙara, kankara da sauran tsarin.

Kowane lokaci na kankara ya kasu kashi biyu: glacial da rikice-rikice. Na farko sune wadanda yanayin muhalli suke da tsananin gaske kuma sanyi yakan faru kusan ko'ina a duniya. A gefe guda kuma, masu rikitarwa sun fi karfin hali, kamar yadda suke a yau.

Har zuwa yanzu, lokaci biyar na shekarun kankara sanannu ne kuma an tabbatar da su: Quaternary, Karoo, Andean-Saharan, Cryogenic da Huronian. Duk waɗannan sun faru tun lokacin da duniya ta kasance.

Ana nuna yanayin kankara ba kawai ta hanyar saukar da kwari a cikin zafin jiki ba, amma kuma ta saurin tashi.

Lokacin Quaternary ya fara shekaru miliyan 2,58 da suka gabata kuma yana wanzuwa har zuwa yau. Karoo, wanda aka fi sani da Permo-Carboniferous period, ya kasance ɗayan mafi tsayi tunda ya ɗauki kimanin shekaru miliyan 100, tsakanin shekaru miliyan 360 da 260 da suka gabata.

A gefe guda kuma, lokacin ƙarancin duwatsu na Andean-Saharan ya ƙare shekaru miliyan 30 ne kawai kuma ya faru tsakanin shekaru 450 zuwa 430 da suka gabata. Lokaci mafi tsauri da ya faru a duniyar tamu babu shakka shine mai cutar. Wannan shine mafi tsananin zamanin kankara a duk tarihin tarihin duniya. A wannan matakin an kiyasta cewa kankara da ta mamaye nahiyoyi sun kai matattarar kasa.

Gwanin Huronian ya fara shekaru biliyan 2400 da suka wuce kuma ya ƙare kimanin shekaru 2100 da suka gabata.

Zamanin kankara na karshe

A yanzu muna cikin tsaka-tsakin rikice-rikice tsakanin Quisernary glaciation. Yankin da iyakokin pola ke zaune ya kai 10% na duk fuskar duniya. Shaidun sun gaya mana cewa a cikin wannan lokacin, an sami shekarun kankara da yawa.

Lokacin da yawan jama'a ke magana akan "The Ice Age" yana nufin shekarun kankara na ƙarshe na wannan lokacin Quaternary. An fara ginin gidan Shekaru 21000 da suka gabata kuma ya ƙare kimanin shekaru 11500 da suka gabata. Ya faru lokaci guda a cikin sassan biyu. An kai manyan fadada kankara a arewacin duniya. A Turai, kankara ta ci gaba, ta mamaye dukkan Burtaniya, Jamus da Poland. Duk Arewacin Amurka an binne shi a ƙarƙashin kankara.

Bayan daskarewa, matakin teku ya fadi mita 120. Manyan fadada teku a yau sun kasance a cikin babban yankin a waccan lokacin. Wannan bayanan suna da matukar dacewa yayin nazarin asalin halittar yawancin dabbobi da tsirrai. Yayin da suke tafiya a duk fadin duniya a cikin shekarun kankara, sun sami damar musanya kwayoyin halitta da yin hijira zuwa wasu nahiyoyi.

Godiya ga ƙananan matakin teku, yana yiwuwa a iya tafiya da ƙafa daga Siberia zuwa Alaska. Manyan talakawan kankara sun kai kaurin mita 3.500 zuwa 4.000, yana rufe kashi na uku na ƙasashe masu tasowa.

A yau, an yi lissafin cewa idan sauran glaciers suka narke, matakin teku zai tashi tsakanin mita 60 zuwa 70.

Abubuwan da ke haifar da dusar kankara

Cigaba da koma bayan kankara suna da nasaba da sanyaya Duniya. Wannan saboda canje-canje ne a cikin yanayin yanayi da canje-canje a cikin kewayar Duniya a kusa da Rana. Hakanan yana iya zama saboda canje-canje a cikin zagawar Rana a cikin taurarin mu, Milky Way.

Wadanda suke tunanin cewa sanya glaciations sanadiyyar abubuwan cikin duniya ne suka yi imanin cewa hakan ya samo asali ne daga tasirin faranti na tectonic da tasirinsu kan yanayin dangi da kuma yawan kwalliyar teku da ta kasa a doron kasa. Wasu suna gaskanta cewa sun faru ne saboda canje-canje a cikin aikin rana ko tasirin yanayin duniyar-Wata.

Aƙarshe, akwai ra'ayoyin da suka danganta tasirin meteorites ko manyan fashewar tsaunuka tare da glaciation.

Abubuwan da ke haifar da rikice-rikice koyaushe suna haifar da rikice-rikice kuma masana kimiyya suna cewa muna gab da kawo ƙarshen wannan lokacin tsakanin kabilu. Shin kuna ganin akwai wani sabon zamanin kankara nan bada jimawa ba?