CH $_\textrm4$ sources estimated from atmospheric observations of CH $_\textrm4$ and its $^\textrm13$ C/ $^\textrm12$ C isotopic ratios: 1. Inverse modeling of source processes: INVERSE ESTIMATES OF METHANE SOURCES, 1
CO2, CO 2, global warming, climate change, greenhouse effect, greenhouse effect gases, emisiones de gases de efecto invernadero, carbon dioxide