Fig. 1

a Monthly mean variations of area-averaged atmospheric CO2 worldwide (gray), South Korea (red), and North Korea (orange) simulated from a 3-D transport model during 2000–2016. The black line indicates the global monthly mean variations of atmospheric CO2 derived from in-situ measurements over the globe. The dotted line represents the linear fit of each monthly variation. b Box plots of trends of simulated atmospheric CO2 over South Korea, North Korea, and the globe