Marielle Saunois¹, Ann Stavert², Benjamin Poulter³, Philippe Bousquet¹, Josep Gili Canadell⁴, Robert B Jackson⁵, Peter A Raymond⁶, Edward J Dlugokencky⁷, Sander Houweling^8,9, Prabir Kumar Patra¹⁰, Philippe Ciais¹ and GCP-CH4 group, (1)LSCE Laboratoire des Sciences du Climat et de l'Environnement, Gif-Sur-Yvette Cedex, France, (2)Commonwealth Scientific and Industrial Research Organisation (CSIRO), Yarralumla, Australia, (3)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (4)CSIRO Marine & Atmospheric Res, Canberra, Australia, (5)Stanford University, Stanford, CA, United States, (6)Yale University, New Haven, CT, United States, (7)NOAA/ESRL Global Monitoring Division, Boulder, CO, United States, (8)SRON, Netherlands Institute for Space Research, Utrecht, Netherlands, (9)Vrije Universiteit Amsterdam, Amsterdam, Netherlands, (10)JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan