Atmospheric methane is a greenhouse gas that has been measured directly since 1983. It has increased steadily to present day levels; this increase is highly correlated with human population growth and with related activities, including agricultural practices.
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This chart represents global average methane concentration in parts per million by volume (ppmv). In 1983, the global averaged value of atmospheric methane was 1.61 ppmv. A century ago, the average was 0.9 ppmv. Atmospheric methane levels continue to rise.