Gases that trap heat in the atmosphere are called greenhouse gases. As their atmospheric concentrations change, scientists expect the amount of energy absorbed by these gases would change accordingly. However, this was not yet proven outside the laboratory until a study was conducted by US Department of Energy’s Lawrence Berkeley Lab Research.
According to Berkeley Lab’s scientists, methane, one of the major greenhouse gases, plays an important role. “We have long suspected from laboratory measurements, theory, and models that methane is an important greenhouse gas,” said Dan Feldman, a scientist from the research lab and study’s lead author of a study focused on methane’s warming effect within the surface of the earth.
The study published online last April 2 in the journal Nature Geoscience is entitled: “Observationally derived rise in methane surface forcing mediated by water vapour trends.” Feldman explains that their study “directly measures how increasing concentrations of methane are leading to an increasing greenhouse effect in the Earth’s atmosphere.”
It was shown in the study that the greenhouse effect of methane followed the trend of its concentration for a decade, from the early 2000’s until the year 2007. This is the first time in the scientific community that the warming effect of methane at the earth’s surface was directly measured. The measurement was conducted in DOE’s field observation site situated in northern Oklahoma and the results confirm the theory on the impact of methane in global greenhouse effect.
The scientists analyzed highly calibrated long-term measurements to isolate the changing greenhouse effect of methane. They did this by looking at measurements over the wavelengths at which methane is known to exert its greenhouse effect and coupled those with a suite of other atmospheric measurements to control for other confounding factors, including water vapor.
In order to isolate the varying greenhouse effect of methane, the scientists conducted highly calibrated, long-term atmospheric measurements. To perform this, Feldman and his team had to look into the measurements within the wavelengths in which methane exhibits its greenhouse effect. These selected measurements were then coupled with a set of atmospheric measurements as a means of regulating other factors such as water vapor.
The data analyzed by the research team were generated by DOE’s Atmospheric Radiation Measurement facilities. These scientists believe that this direct field measurements enable them to have a more accurate and complete picture of how atmospheric greenhouse gas concentrations are related with their warming effect on the Earth’s surface.