A ƙarshen shekarun 1960, Mikhail Ivanovich Budyko ya yi aiki tare da samfurori na sauyin yanayi na sauyin yanayi na sauyin yanayi don bincika tasirin tasirin kankara. Ya gano cewa sake dawowa na kankara-albedo ya haifar da madaidaicin sake dawowa a cikin tsarin yanayi na duniya. Da yawa snow da kankara, yawancin hasken rana yana sake komawa cikin sararin samaniya kuma saboda haka ƙasa mai sanyi yana girma kuma yana da yawa. Sauran nazarin sun gano cewa gurbatawa ko fashewar dutsen mai fitad da wuta na iya haifar da farkon lokacin kankara.A cikin shekarun 1980, Atsumu Ohmura, mai binciken ilimin ƙasa a Cibiyar Fasaha ta Tarayyar Switzerland, ya gano cewa hasken rana da ke buga farfajiyar duniya ya ragu da fiye da 10% a cikin shekaru talatin da suka gabata. Duk da binciken da ya samu game da dumamar duniya <unk> yanayin zafi na duniya ya kasance yana ƙaruwa a cikin shekarun 70s.
Shekarar 1994