Climate change; International law; Softening of international law; Paris Agreement; Bottom-up; Top-down LB Paris Agreement UN Framework Convention on Climate Change air pollution prevention black carbon emissions climate change mitigation climate policy environmental policy international climate law international environmental law methane emissions multilevel governance policy integration polycentric governance science-policy interface thema EDItEUR::L Law::LB International law thema EDItEUR::L Law::LB International law::LBB Public international law::LBBP Public international law: environment transnational environmental law