An international study has determined that methane levels in the atmosphere have started to rise after almost eight years of near-zero growth.

According to a report in ABC News, the study involved CSIRO, the Massachusetts Institute of Technology (MIT), Scripps Institution of Oceanography and the University of Bristol.

Dr Paul Fraser of the CSIRO, who co-authored the study, said that samples taken from 12 stations across a global network showed a trend upwards in methane levels.”After seven years (of zero growth), methane has started to rise again to growth rates of the early 1990s,” Fraser said.

The chief research scientist in the Division of Marine and Atmospheric Research said that the increase in methane could lead to an acceleration in global warming.”If methane concentrations continue to grow at the current rate then it will be once again the second-most important greenhouse gas to control after CO2 over the next few decades,” he said.

Fraser said that methane accounts for about 20 percent of all greenhouse gases since the industrial revolution.