"This is a great result that generated some scientific surprises and will help us to understand what controls methane in the atmosphere and its links with climate," said CSIRO Marine & Atmospheric Research scientist David Etheridge.

The team has published an article in the 9 September issue of international scientific journal Science that reveals data charting historical atmospheric methane concentration and its possible causes.

The data suggests the burning of grass and woodlands for agricultural and hunting purposes may have generated methane gas far in excess of what would be expected of early human population sizes, and that warmer periods of history witnessed dramatic increases in methane release due to wildfires, a grim indicator for future climate change.

"Looking at the last 2000 years, we've found much higher than expected levels of methane from forest and grassland fires until about 1000 years ago when these emissions began to drop dramatically," said team leader Dominic Ferretti of NIWAR.

"This tallies well with both natural climate change and human land use."

Methane accounts for around 20% of the warming effects of greenhouse gases by slowing the release of radiated heat away from the earth, and the data indicates that increased levels of global warming could see a feedback effect where warmer temperatures create and are simultaneously increased by higher methane levels.

By using ice core research, chemical analysis and atmospheric composition modelling, the team hopes their data will help answer why the atmospheric composition of methane has changed and what humanity's role has been. This will help researchers predict how it may change in the future and what steps can be taken to control methane emissions.

EnvironmentalManagementNews.net