Bai kamata mutane su ketare wasu iyakoki ba, don kada su zo ga bala'in muhalli, wanda zai zama babbar barazana ga wanzuwar ɗan adam a duniya.
Masu binciken sun ce akwai iyakoki iri biyu. Masanin muhalli na Jami'ar Minnesota Jonathan Foley ya ce daya daga cikin irin wannan iyaka ita ce abin da zai kai ga wani bala'i ya faru. A wani yanayin, waɗannan canje-canje ne a hankali, waɗanda, duk da haka, sun wuce iyakar da aka kafa a tarihin ɗan adam.
Anan akwai irin waɗannan iyakoki guda bakwai waɗanda a halin yanzu ke ƙarƙashin tattaunawa mai ƙarfi:
Ozone a cikin stratosphere
Layin ozone na duniya zai iya kaiwa inda mutane za su iya samun tan a cikin mintuna idan masana kimiyya da shugabannin siyasa ba su yi aiki tare don shawo kan sakin sinadarai masu lalata ozone ba. Yarjejeniyar Montreal a 1989 ta haramta chlorofluorocarbons, ta haka ne ya ceci Antarctica daga kallon wani rami na ozone na dindindin.
Masana muhalli sun yi imanin cewa mahimmancin batu zai kasance raguwa 5% a cikin abubuwan da ke cikin ozone a cikin stratosphere ( saman Layer na yanayi ) daga matakin 1964-1980.
Mario Molina, shugaban Cibiyar Nazarin Dabarun Makamashi da Kare Muhalli a birnin Mexico, ya yi imanin cewa raguwar 60% na ozone a duniya zai zama bala'i, amma asarar a yankin na 5% zai cutar da lafiyar ɗan adam da muhalli. .
Amfani da ƙasa
A halin yanzu, masana muhalli sun sanya iyaka 15% kan amfani da filaye don noma da masana'antu, wanda ke ba dabbobi da tsire-tsire damar kula da yawan jama'a.
Irin wannan iyaka ana kiransa "ra'ayi mai hankali", amma kuma wanda bai kai ba. Steve Bass, babban jami'in cibiyar kula da muhalli da ci gaban kasa da kasa da ke Landan, ya ce adadin ba zai gamsar da masu tsara manufofi ba. Ga yawan mutane, amfani da ƙasa yana da fa'ida sosai.
Ƙuntatawa kan manyan ayyukan amfani da ƙasa gaskiya ne, in ji Bass. Wajibi ne a samar da hanyoyin hana aikin gona. Hanyoyin tarihi sun riga sun haifar da lalacewar ƙasa da guguwar ƙura.
Ruwan sha
Ruwa mai dadi shine ainihin bukatu na rayuwa, amma mutane suna amfani da adadi mai yawa don aikin noma. Foley da abokan aikinsa sun ba da shawarar cewa janyewar ruwa daga koguna, tabkuna, tafkunan karkashin kasa bai kamata ya wuce nisan kilomita 4000 a kowace shekara ba - wannan kusan girman tafkin Michigan ne. A halin yanzu, wannan adadi yana da nisan kilomita 2600 a kowace shekara.
Noma mai zurfi a wani yanki na iya cinye yawancin ruwa mai kyau, yayin da a wani yanki na duniya mai arzikin ruwa, mai yiwuwa babu noma kwata-kwata. Don haka hane-hane akan amfani da ruwa mai kyau yakamata ya bambanta daga yanki zuwa yanki. Amma ainihin ra'ayin "iyakoki na duniya" ya kamata ya zama wurin farawa.
teku acidification
Matsakaicin iskar carbon dioxide na iya tsoma ma'adanai da murjani reefs da sauran rayuwar ruwa ke buƙata. Masanan ilimin halittu sun bayyana iyakar oxidation ta hanyar kallon aragonite, ginin ma'adinai na murjani reefs, wanda ya kamata ya zama akalla 80% na matsakaicin masana'antu kafin masana'antu.
Adadin ya dogara ne akan sakamakon gwaje-gwajen dakin gwaje-gwaje da suka nuna cewa ragewar aragonite yana rage saurin girma na murjani, in ji Peter Brewer, masanin kimiyyar teku a Cibiyar Binciken Aquarium ta Monterey Bay. Wasu rayuwar ruwa za su iya tsira daga ƙananan matakan aragonite, amma karuwar acidification na teku zai iya kashe yawancin nau'in da ke zaune a kusa da raƙuman ruwa.
Asarar halittu masu rai
A yau, jinsuna suna mutuwa a cikin adadin 10 zuwa 100 a kowace shekara. A halin yanzu, masu ra'ayin muhalli sun ce: Hukuncin jinsunan kada su wuce bakin ƙofar 10 a kowace shekara a shekara. Adadin bacewar da ake yi yanzu ya wuce a sarari.
Wahalar kawai shine tare da bin diddigin nau'in, in ji Christian Samper, darektan gidan tarihi na Smithsonian National Museum of Natural History a Washington. Wannan gaskiya ne musamman ga kwari da yawancin invertebrates na ruwa.
Samper ya ba da shawarar rarraba ƙimar karewa zuwa matakan barazana ga kowane rukunin nau'in. Don haka, za a yi la'akari da tarihin juyin halitta na rassa daban-daban na bishiyar rayuwa.
Cycles na nitrogen da phosphorus
Nitrogen shine mafi mahimmancin sinadari, abin da ke cikinsa shine ke ƙayyade adadin tsire-tsire da amfanin gona a duniya. Phosphorus yana ciyar da tsirrai da dabbobi duka. Ƙayyadaddun adadin waɗannan abubuwan na iya haifar da barazanar bacewar nau'ikan.
Masana ilimin halittu sun yi imanin cewa bai kamata ɗan adam ya ƙara fiye da 25% zuwa nitrogen da ke zuwa ƙasa daga yanayi ba. Amma waɗannan hane-hane sun zama na sabani. William Schlesinger, shugaban Cibiyar Nazarin Halittar Muhalli ta Millbrook, ya lura cewa ƙwayoyin cuta na ƙasa na iya canza matakan nitrogen, don haka ya kamata sake zagayowar ta ya zama ƙasa da tasirin ɗan adam. Phosphorus wani nau'i ne mara ƙarfi, kuma ana iya raguwar ajiyarsa cikin shekaru 200.
Yayin da mutane ke ƙoƙarin kiyaye waɗannan ƙofofin, amma samarwa mai cutarwa yakan tara mummunan tasirinsa, in ji shi.
Canjin yanayi
Yawancin masana kimiyya da 'yan siyasa suna la'akari da sassa 350 a kowace miliyan a matsayin iyakacin lokaci na dogon lokaci don yawan adadin carbon dioxide na yanayi. Wannan adadi ya samo asali ne daga tunanin cewa wuce gona da iri zai haifar da ɗumamar digiri 2 na ma'aunin celcius.
Koyaya, an yi jayayya da wannan adadi saboda wannan matakin na iya zama haɗari a nan gaba. An sani cewa 15-20% na CO2 hayaki ya kasance a cikin yanayi har abada. Tuni a zamaninmu, sama da ton tiriliyan 1 na CO2 an fitar da su kuma ɗan adam ya riga ya wuce rabin zuwa iyaka mai mahimmanci, wanda fiye da haka ɗumamar duniya za ta fita daga sarrafawa.