A karshen Cenozoic a lokacin Cretaceous lokacin akwai wani kari mai yawa wanda ya hada da dukkan dinosaur da yawancin halittu masu rai. Ka'idar da aka fi yarda da ita ita ce faduwar babban meteorite a yankin Amurka ta Tsakiya. Bayan yawan turɓaya a cikin iska, sun hana hasken rana isa zuwa saman, suna ba da tsire-tsire da ba sa iya ɗaukar hoto kuma yana shafar sarkar abinci sosai. Yana da lokacin da kashi 35% na dukkan rayuwar duniya suka mutu, suka bada hanya Lokacin kankara.
Shin kana son sanin komai game da abin da ya faru a zamanin kankara? Shin muna gab da wani zamanin kankara? A cikin wannan sakon zaku iya koyon komai.
Bacewar flora da fauna
Bacewar manyan dabbobi masu rarrafe ya ba da sanannun zamanin kankara. A wannan zamanin, dabbobi masu shayarwa sunyi amfani da damar da dinosaur suka bari don ninkawa da yaduwa. Kari akan haka, godiya ga gicciyen kwayoyin halitta, an haifi sabbin jinsuna don haka dabbobi masu shayarwa suka banbanta. A ƙarshe, faɗaɗuwarsu ta kasance ta yadda suka ɗora mamayar su a kan sauran ƙasashe. Daga cikin iyalai 10 da suka wanzu a farkon wannan zamanin kankara, sun zama kusan 80 a cikin Eocene cikin shekaru miliyan 10 kacal na juyin halitta.
Kalli wannan lokacin ilimin kasa idan baka sanya kanka da kyau a kan sikelin lokaci ba
Yawancin dangin zamani masu shayarwa suna zuwa Oligocene, ma’ana, kimanin shekaru miliyan 35 da suka gabata. A lokacin ne a cikin Miocene (tsakanin shekaru miliyan 24 zuwa 5 da suka gabata) lokacin da aka rubuta mafi yawan nau'ikan halittu a lokacin kankara.
Akasin shahararren imani, shekarun kankara ba yana nufin cewa duk duniyar tamu a rufe take da kankara ba, amma waɗannan sun fi girma fiye da al'ada.
A wannan lokacin na ƙarshe Hominoidea ta farko da ta gabata ta bayyana, kamar su Proconsul, Dryopithecus da Ramapithecus. Farawa a cikin Miocene, yawan dabbobi masu shayarwa sun fara raguwa kuma, sakamakon manyan canjin canjin yanayin da ya faru a lokacin Pliocene, kimanin shekaru miliyan 2 da suka gabata, yawancin jinsuna sun ɓace.
A lokacin ne lokacin da dusar kankara ke shirin farawa a cikin Pleistocene inda 'yan takara suke ci gaba kuma daya daga cikinsu zai gabatar da mulkinsa: yanayin Homo.
Halaye na zamanin kankara
An ayyana shekarun kankara azaman lokaci wanda halin dindindin na babban murfin kankara ke kasancewa. Wannan kankara ta fadada zuwa akalla daya daga cikin sandunan. Duniya an san cewa ta kashe 90% na lokacinta yayin shekaru miliyan na ƙarshe a cikin kashi 1% na yanayin 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.
Shekarun kankara huɗu da suka gabata sun faru ne tsakanin tazarar shekaru miliyan 150. Saboda haka, masana kimiyya suna tunanin cewa sun samo asali ne daga canjin yanayin 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 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.
Shin muna kusa da sabon zamanin kankara?
A wannan shekara hunturu a kudu maso yamma na yankin Iberian ya dade fiye da yadda aka saba. Guguwar ta kasance mai sanyaya kai digiri 2 kasa da matsakaicin shekaru 20 da suka gabata. Watan Yuni shima ya kasance mara sanyi sosai tare da yanayin zafi digiri 4 ƙasa da yadda yake.
Sauye-sauyen yanayi koyaushe suna faruwa a duniyar kuma ba saboda bayyanar mutum da juyin juya halin masana'antu ba. Waɗannan canje-canje ne suka haifar da fure da fauna na Duniya don canzawa kuma akwai lokutan glacial da rikice rikice.
Akwai dalilai da yawa wadanda suke shiga cikin yanayin duniya. Saboda haka, kodayake masana kimiyya sun nuna cewa ɗumamar ɗumbin nauyin keɓaɓɓen gas ne (mahada), bai dogara da shi kawai ba. Nutsuwarsu na ci gaba da hauhawa tsawon shekaru, amma zafin jiki bai karu ba ta hanyar haɗin kai. Akwai lokacin zafi mai zafi kodayake ba a jere ba.
Duk wannan yana sanyawa masana kimiyya suyi tunanin cewa, kodayake muna haifar da ɗumamar yanayin duniya cikin sauri fiye da yadda yanayi yake, ba za mu iya dakatar da ƙarshen lokacin rikice-rikice da shigowar sabon zamanin kankara ba.
Menene ya faru a cikin shekarun kankara na ƙarshe?
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 "Lokacin kankara" yana nufin lokacin ƙarancin ƙarshe na wannan lokacin. Quaternary ya fara shekaru 21000 da suka wuce kuma ya ƙare shekaru 11500 da suka wuce. 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 na yau sun kasance don wancan zamanin akan tudu. A yau, an yi lissafin cewa idan sauran glaciers suka narke, matakin teku zai tashi tsakanin mita 60 zuwa 70.
Me kuke tunani game da zuwan sabon zamanin kankara? Bari mu sani a cikin maganganun.
Ni mutum ne wanda a cikin 1980s yayi kiyasin ba kawai cewa wani sabon zamanin Zamani ya kusa amma kuma yana yiwuwa muna raye muna wannan shekarun ba tare da mun sani ba. Yanayin yanayin zafi, yanayin halittar da dole ne Duniyar ta bi har ma da dumamar duniyar ita alamomi ne da suka fi tasiri a ra'ayi na. Game da mafi yawan rikice-rikice na alamomi ko ɗumamar duniya, binciken da aka gudanar a Antarctica wanda ya yanke shawarar cewa ɗumamar ɗumamar duniya ko kuma duniyar da ke gaba da lokacin kankara ya kamata a yi la’akari da ita.
Kamar yadda kuka nuna, Zamanin kankara abu ne wanda ba za a iya warwarewa ba kuma ba za a iya hana shi ba:
“Duk wannan ya sa masana kimiyya suyi tunanin, duk da cewa muna haifar da dumamar yanayi a cikin sauri fiye da yadda dabi’a ke yi, ba za mu iya dakatar da karshen lokacin cacar baki da kuma shigowa da wani sabon zamani kankara. "
Injiniya Lee carroll, a cikin karatuttukan da yake gabatarwa da kuzarin Kryon, ya gayyace mu mu shirya don lokacin kankara da muka riga muka fara a wannan shekarar ta 2019.
Shaidar ita ce, kamar yadda kuka nuna, a cikin bayanan iskar da aka makale a cikin silinda na kankara a Antarctica, kuma a cikin zoben itacen. Yana gayyatar mu don haɓaka wadataccen makamashi a cikin gida, al'umma, da matakan gidaje. Saboda «ba a shirya layin wutar lantarki don tsayayya da zamanin kankara ba. Yana iya kasawa. Kuma zai gaza »