Greenhouse da icehouse Duniya

A cikin tarihin yanayi na Duniya (Paleoclimate) yanayin sa ya canza tsakanin jihohi biyu na farko: **greenhouse da icehouse Duniya**. Dukkanin jihohin yanayi suna da miliyoyin shekaru kuma bai kamata a rikita su da ƙananan lokutan glacial da Interglacial ba, waɗanda ke faruwa a matsayin matakai masu sauyawa a cikin lokacin ƙanƙara (wanda aka sani da zamanin kankara) kuma suna da alaƙa da ƙasa da shekaru miliyan ɗaya. Akwai lokutan kankara guda biyar da aka sani a tarihin yanayi na Duniya, wato Huronian, Cryogenian, Andean-Sahara (wanda aka fi sani da Early Paleozoic), Late Paleozoic da Late Cenozoic glaciations.

Babban abubuwan da ke tattare da canje-canje na yanayin yanayi an yi imanin cewa su ne maida hankali ga iskar gas mai tsabta kamar  (CO) da kuma ƙananan methane (), canje-canje a cikin yanayin duniya, canje-canje masu tsawo a cikin hasken rana, da canje-canjen teku da orogenic daga yanayin tectonic. Greenhouse da kankara lokutan sun taka muhimmiyar rawa a cikin juyin halitta na rayuwa a Duniya ta hanyar kai tsaye da kai tsaye tilasta daidaitawa da juyawa a wurare daban-daban a fadin lokaci. 

## Gidan Gishiri na Duniya
Greenhouse Earth" wani lokaci ne wanda babu wani kankara na nahiyar da ke ko'ina a duniya. Bugu da ƙari, matakan carbon dioxide da sauran iskar gas (kamar tururin ruwa da methane) suna da yawa, kuma Yanayin zafi na teku (SSTs) ya kasance daga 28 ° C (82.4 ° F) a cikin wurare masu zafi zuwa 0 ° C (32 ° F) A cikin Yankunan polar. Duniya ta kasance a cikin yanayin greenhouse na kusan kashi 85% na tarihinta. 

Bai kamata a rikita jihar da tasirin greenhouse ba, wanda shine maɓallin da ba za a iya juyawa ba wanda ya dace da tasirin greenhouse da ke gudana a Venus. IPCC ta bayyana cewa "'wani sakamako mai zurfi' - mai kama da  Venus - ya bayyana kusan babu damar da ayyukan ɗan adam suka haifar da shi".

### Dalilan da suka haifar
Akwai ra'ayoyi da yawa game da yadda za a yi greenhouse ƙasa. Manufofin yanayi na yanayin ƙasa suna nuna cewa akwai alaƙa mai ƙarfi tsakanin yanayin greenhouse da manyan matakan CO 2 .  Duk da haka, yana da mahimmanci a gane cewa an fassara manyan matakan CO 2 a al'ada a matsayin ra'ayi ga yanayin duniya maimakon a matsayin direba mai zaman kansa, amma an gano direbobin geologic na CO 2 da sauyin yanayi.  Wasu al'amura a maimakon haka sun taka muhimmiyar rawa wajen tasiri yanayi na duniya ta hanyar canza yanayin teku da na yanayi  da kuma kara yawan adadin hasken rana da yanayin duniya ke sha.  Irin waɗannan al'amura na iya haɗawa amma ba'a iyakance ga canjin tectonic ba wanda ke haifar da sakin iskar gas (kamar CO 2 da CH 4 ) ta hanyar aikin volcanic .  Volcanoes suna fitar da yawan CO 2 da methane zuwa sararin samaniya lokacin da suke aiki, wanda zai iya kama isasshen zafi don haifar da tasirin greenhouse. A duniya, yawan iskar iskar gas kamar carbon dioxide (CO 2 ) da methane (CH 4 ) sun fi girma, suna kama makamashin hasken rana a cikin yanayi ta hanyar tasirin greenhouse. Methane, babban sinadarin iskar gas, shi ne ke da alhakin fiye da kashi hudu na dumamar yanayi a halin yanzu. Yana da ƙaƙƙarfan gurɓatacce tare da yuwuwar dumamar yanayi mai ninki 80 fiye da CO 2 a cikin shekaru 20 bayan an shigar da shi cikin yanayi. Ƙaruwa a cikin kullun rana yana ƙara yawan adadin kuzarin hasken rana da ke shiga cikin yanayi na duniya,  da kuma canje-canje a cikin bliquity da ƙaƙƙarfan yanayi yana ƙara yawan adadin hasken rana da ke shiga cikin yanayin duniya. 

## Manazarta