Methane Rate of increase: 0.9% annually 1.72 1.70 1.6 8 CH 1.66 1.64 1.62 1984 1986 1988 990 1992 1994 YEAR this increase is highly correlated with human population growth i Atmospheric methane has increased steadily to present day leve and with related activities, including agricultural practicesMethane Atmospheric methane has increased steadily to present day levels; this increase is highly correlated with human population growth and with related activities, including agricultural practices. Rate of increase: 0.9% annually