Chandra, N., P. K. Patra, J. S. H. Bisht, A. Ito, T. Umezawa, N. Saigusa, S. Morimoto, S. Aoki, G. Janssens-Menhout, and R. Fujita, M. Takigawa, S. Watanabe, N. Saitoh, and J. G. Canadell, 2021: Emissions from the oil and gas sectors, coal mining and ruminant farming drive methane growth over the past three decades. J. Meteor. Soc. Japan, 99,
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Plain Language Summary: Methane (CH4) is an important greenhouse gas and plays a significant role in tropospheric and stratospheric chemistry. CH4 growth rate (i.e., year to year change) in atmosphere varied in three distinct phases in the past three decades (1988-2016); namely, the periods of slowed (1988-1998), quasi-stationary (1999-2006) and renewed (2007-2016) growth phases. These distinct growth rate phases are explained by the anomalies in global and regional emissions that are estimated with an atmospheric chemistry-transport model (ACTM) based inverse modelling framework and observations from 19 sites worldwide. The anomalies in global and regional emissions are further attributed into different sectorial categories with the help of emission inventory.
- We proposed that CH4 growth anomalies can be explained mainly by the changes in anthropogenic emissions, from the oil and gas exploitation, coal mining and livestock farming.
- The natural phenomena, such as the Mt. Pinatubo eruption and more frequent El Niño in the 1990s, have also helped to slow down the growth and achieve the quasi-stationary growth rate.
- Estimated CH4 emission anomalies are evaluated against independent aircraft observations, 13C-CH4 isotopic signature, and other inventory/inverse modelling results.