Strategies for measuring and reducing methane emissions from beef cattle in northern Australia Ed Charmley a , Sandra Eady b and Chris McSweeney c CSIRO Livestock Industries, a Townsville, b Armidale and c Brisbane Abstract Methane is a greenhouse gas (GHG) produced as a by-product of rumen fermentation. The northern cattle industry produces about 4.5% of Australia’s total GHG emissions. Livestock methane emissions can be reduced through adoption of changed management and new technologies. If the Carbon Farming Initiative (CFI) is passed through parliament, there will be financial incentives to reduce emissions. A major challenge in Australia’s north is simply measuring methane emissions. However in recent years, significant advancement in this area has been achieved. A range of methods are now available experimentally and are being developed specifically for extensive grazing conditions. In particular the use of open-path laser techniques to measure methane concentration in the atmosphere down-wind of grazing cattle can be used to estimate emissions from cattle on pasture. By validating these data with intensive techniques from animals in chambers we now have a viable approach to measure emissions from cattle under extensive grazing conditions. Currently, the laser technique is being used in a number of commercial situations in northern Australia to assess the variability in methane emissions across different production systems and land types. These data will inform new models that will give more accurate predictions of methane emissions per animal, per hectare and per unit product. Such information is critical if we are to quantify the effects of management and mitigation technologies on methane emissions. These developments will ensure that management decisions can be made to optimise productivity and carbon outcomes. A range of options exist for mitigating methane. Some can be implemented today, but these usually have low impact on emissions, others are further into the future but may offer real hope of a genuine reduction in methane emissions. Mitigation options fall into four broad categories; management changes, dietary manipulation, rumen manipulation and genetic improvement. Not all these options are suitable in every circumstance and for the northern cattle industry many potential mitigation practices are simply impractical. For the producer currently, the most promising options for abating methane emissions focus around sound management decisions that also improve profitability through increased growth and reproductive rates. While these options will reduce the amount of methane produced per kg saleable product, they may not reduce total emissions form the property. While methane emissions from the northern cattle industry represent a challenge, there are also potential opportunities if we have the means to reduce methane emissions. Recent research is providing answers to the measurement and mitigation of methane from the northern cattle industry. Introduction The beef industry in northern Australia is a significant contributor to the economy of the region, ranked third behind mining and tourism in terms of economic value. The Northern Australia Land