Evidence that increasing concentrations of methane are leading to an increasing greenhouse effect in the The scientists used radiometers to isolate the signal of methane’s greenhouse effect. Source: U.S. Department of Energy Atmospheric Radiation Measurement Climate Research FacilityThe scientists used radiometers to isolate the signal of methane’s greenhouse effect. Source: U.S. Department of Energy Atmospheric Radiation Measurement Climate Research FacilityEarth's atmosphere has been documented by researchers from the US Department of Energy’s Lawrence Berkeley National Laboratory. Data from a field observation site in northern Oklahoma indicate that the greenhouse effect from methane tracked the global pause in methane concentrations in the early 2000s and began to increase at the same time that concentrations began to rise in 2007.

Highly calibrated, long-term measurements were analyzed to isolate the changing greenhouse effect of methane. The researchers examined measurements over the wavelengths at which methane exerts its greenhouse effect and coupled these with a suite of other atmospheric measurements to control for other confounding factors, including water vapor.

The trend in methane-associated radiative forcing observed after 2006 was 0.026 ± 0.006 (99.7% CI) W m2 yr−1. The seasonal-cycle amplitude and secular trends in forcing are influenced by a corresponding seasonal cycle and trend in atmospheric methane.

This study was enabled by the comprehensive measurements of the Earth’s atmosphere that the U.S. Department of Energy has routinely collected for decades at its Atmospheric Radiation Measurement facilities.

To contact the author of this article, email shimmelstein@globalspec.com