Hankalin yanayi gwargwadon yadda yanayin duniya zai sanyaya ko dumi bayan canjin tsarin yanayi, misali, nawa zai dumama don ninkawa a cikin carbon dioxide (CO2) maida hankali. A cikin maganganun fasaha, fahimtar yanayin sauyin yanayi shine matsakaicin canjin yanayin Duniyar saboda martani ga canje-canje a tilasta tilas, bambanci tsakanin makamashi mai shigowa da mai fita a Duniya. Hankalin yanayi shine babban ma'auni a kimiyyar yanayi, da kuma yanki mai da hankali ga masana kimiyyar yanayi, wadanda ke son fahimtar sakamakon karshe na canjin yanayin anthroprogenic. Kasa ta dumi a matsayin sakamakon kai tsaye na ƙaruwar yanayin CO2, kazalika da karin yawan sauran iskar gas mai guba kamar su nitrous oxide da methane. Karuwa yanayin zafi yana da tasiri na biyu kan tsarin sauyin yanayi, kamar haɓaka tururin ruwa na yanayi, wanda shi ma gas ne mai gurɓataccen yanayi. Saboda masana kimiyya ba su san ainihin ƙarfin waɗannan bayanan yanayi ba, yana da wuya a iya faɗi daidai adadin dumamar da zai samu sakamakon ƙaruwar da aka bayar a cikin yawan iskar gas.