Ragewa da Haɗuwa

Contraction da Convergence (C&C) wani tsari ne na duniya da aka tsara don rage hayakin gas don yaki da Canjin yanayi. Cibiyar Global Commons (GCI) ce ta tsara shi a farkon shekarun 1990, dabarun Contraction da Convergence ya ƙunshi rage yawan hayaki na iskar gas zuwa matakin aminci (ƙuntata), wanda ya haifar da kowace ƙasa da ke kawo hayaki ga kowane mutum zuwa matakin da ya dace da dukkan ƙasashe (haɗuwa). 

An yi niyyar samar da tushen yarjejeniyar kasa da kasa wacce za ta rage hayakin carbon dioxide don kauce wa canjin yanayi mai haɗari, carbon dioxide yana ɗaya daga cikin manyan iskar gas da ke da alhakin tasirin greenhouse a Duniya.

An bayyana shi a matsayin tsari mai sauƙi na lissafi. Ana iya amfani da wannan tsari a matsayin hanyar da duniya za ta daidaita matakan carbon a kowane matakin. Masu ba da shawara game da raguwa da haɗuwa sun jaddada cewa tattaunawar da aka yi a Yarjejeniyar Tsarin Majalisar Dinkin Duniya kan Canjin Yanayi (UNFCCC) ana gudanar da su ta hanyar 'mahimmanci' na UNFCCC (mai aminci da kwanciyar hankali na GHG a cikin yanayin duniya) sannan ka'idodin shirya ('kariya' da 'daidaita'). C&C an ambaci shi sosai kuma ana tallafawa. Lissafin C & C yanzu an saka shi a cikin Yankin Biyu na GCI's Carbon Budget Accounting Tool.

## Shirin C & C
Al'amarin "haɗuwa" ya shafi rabon haƙƙin hayaki tsakanin ƙasashe ko yankuna a duk duniya. Da farko, waɗannan haƙƙoƙin za su dogara ne akan hayaki na yanzu amma a hankali za su haɗu zuwa daidaitattun haƙƙoƙinsa na kowane mutum a duk faɗin duniya, dangane da tattaunawar "haɗin kai". Lokaci na haɗuwa yana da mahimmanci, kamar yadda kwanan wata da ya gabata zai haifar da karuwar haƙƙoƙi ga ƙasashe masu ƙarancin hayaki (yawanci ƙasashe mafi talauci), yayin da jinkirin haɗuwa zai iya hana ci gaban waɗannan ƙasashe.

Da zarar an cimma daidaituwa, duk hakkokin ƙasashe za su ci gaba da raguwa, biyo bayan abubuwan da suka faru don bin Yarjejeniyar Tsarin Majalisar Dinkin Duniya kan Canjin Yanayi (UNFCCC).

Masu sukar suna jayayya cewa mayar da hankali ga kowane mutum na iya karfafa kasashe su kara yawan jama'arsu don samun ƙarin hakkoki. Dangane da wannan damuwa, Cibiyar Global Commons (GCI) ta haɗa aikin shekara-shekara na yawan jama'a a cikin samfurin. Masu amfani za su iya zaɓar kowane kwanan wata tsakanin 2000 da 2050, bayan haka yawan jama'a ba zai sake samar da ƙarin haƙƙoƙi ba.

## Matsayi masu karɓa
Dukkanin mahimman ra'ayi na Contraction da Convergence da takamaiman tsarin da Cibiyar Global Commons ta ba da shawara za a iya daidaitawa don karɓar ƙuntatawa mai yawa na fitar da carbon, daga matsakaici zuwa matakan da suka fi tsananin, dangane da matakin da ake so na haɗarin da ke da alaƙa da yawan iskar gas.

Koyaya, masu goyon bayan Contraction da Convergence suna tabbatar da cewa matakin aminci da aka ba da shawarar don daidaita yawan iskar gas mai ɗorewa ya fi ƙasa da abin da wasu ke bayarwa. Suna jayayya da ra'ayin cewa yawan carbon dioxide na yanayi wanda ya kai kashi 550 a kowace miliyan ta hanyar girma (ppmv) zai kasance lafiya.

Sun yi imanin cewa irin wannan matakin yana ɗauke da haɗarin haifar da tasirin tasirin yanayi mara tabbas. A matsayin matakan kariya, suna ba da shawara don daidaita yawan carbon dioxide na yanayi a kewayon 350-450 ppv. Don tallafawa wannan matsayi, GCI ta yi nuni da nazarin lambobi game da zato mai kyau game da sinks na carbon da aka samu a cikin Dokar Yanayi ta Burtaniya.

## Tarihi
Asalin shigarwar GCI ya fito ne daga 1989 kuma ya haifar da wata sanarwa da aka buga a 1990 a cikin Guardian Yuni 18, 1991.

An haɓaka tsarin lissafin C & C na yau da kullun a cikin shekaru uku don mayar da martani ga manufar da ka'idodin UNFCCC. Tsakanin 1992 da 1995 a buƙatar Kwamitin Gwamnati kan Canjin Yanayi, GCI ta gudanar da bincike wanda ke nuna alamun fadadawa da bambance-bambance, wanda ya fallasa karuwar rashin daidaituwa a ci gaban duniya tsakanin kasashe masu tasowa da masu tasowa. Binciken ya kuma jaddada cewa kasashe masu tasowa za su dauki nauyin tasirin tasirin canjin yanayi. Dangane da waɗannan abubuwan da suka shafi, Cibiyar Global Commons (GCI) ta haɓaka Contraction and Convergence (C&C) a matsayin tsari don rage mummunan tasirin da ke tattare da waɗannan bambance-bambance.

## Manazarta