Rice Warmer

According to the CSIRO methane gas density concentrations in the atmosphere have approximately doubled since the industrial revolution, rising from 700ppb to ~1795 in 2010. Over the last decade however methane levels in the atmosphere have been relatively stable. Between 2007-2009 there was a small spike in methane levels, but following that the growth rate returned to approximately zero.

Sources of methane gas emissions

- Methane is emitted from both natural sources and human activities
- Natural emissions are dominated by anaerobic breakdown of organic matter in wetlands
- Human activities account for more than 60% of global emissions as per below:

Source - % total Anthropogenic emissions
Fossil fuels - 25%
Livestock - 25%
Rice cropping - 20%
Landfill methane - 20%
Biomass burning - 10%

Causes of increase in methane gas

A report by CSIRO and other organisations that was published in 2010 in ECOS found that the rise in methane emission levels in the atmosphere was caused by the release of methane previously stored in wetlands in the arctic. The warmer summers of 2006 and 2007 as well as the wetter conditions in the tropics contributed to the release of methane from the arctic wetlands. The report suggests that with climate change and unpredicted weather conditions that there is a risk of continued spike in atmospheric methane being released from arctic wetlands.

Cows methane gas

The most commonly discussed contributor to atmospheric methane emissions is methane gas from cows. However as noted above cows methane gas contributes 25% of anthropogenic emissions globally, the same as fossil fuels and just slightly more than rice growing and landfill.

Reducing emissions from cattle

The Australian cattle industry is focussed on looking at how to reduce methane gas emissions from ruminant (cattle and sheep) digestion. Meat and Livestock Australia in partnership with the federal government has a $28 million project underway with 18 different research projects under the banner of Reducing Emissions from Livestock Research Program (RELRP). Under this program research bodies from across the country are looking at how to more effectively measure methane gas, such as with methane gas detector. Researchers are also investigating whether there are particular animals that naturally produce less methane gas and if so, if this can be selectively bred for.

Another area of focus under the RELRP is whether different feeds can have an impact on reducing cows methane gas. One of the projects funded under RELRP is being undertaken by Dr Ed Charmley from the CSIRO. Dr Charmley has recently reported some positive findings with feeding cattle a Mexican fodder tree, with methane gas detector showing that it leads to cows methane gas being 20% lower than cows that don’t eat the Mexican fodder tree.

Find out more about methane gas and farms in Australia at Red Meat Green Facts.