Reducing Australia’s largest source of methane emissions

By Dr Courtney Regan.

My name is Courtney Regan. I am a resource economist working within CSIRO’s Towards Net Zero team. I work on range of projects that are looking to better quantify and model GHG emissions from the land sector and economically assess mitigation options.  

Did you know that Australia’s largest source of methane emissions come cattle and sheep burps?

What is enteric fermentation?

Ruminants like cattle, sheep and goats have four stomachs which helps them turn very poor-quality feed sources into meat, wool and milk. The bacteria in the gut of a ruminants help them break down hard to digest material like cellulose, material we cannot digest, into energy for the animal to use. This process is known and enteric fermentation, and it produces a lot of methane as a by-product that the animals burp out into the atmosphere. Individually the amount of methane is very small, but multiplied by the tens of millions of animals across the landscape and we have a significant problem. 

What makes this issue so difficult to address?

I would like to compare it with the previous presentation on the challenge of green steel. Green steel production presents a large engineering challenge that will need significant capital expenditure to realise. While an enormous challenge, the implementation of the solutions are confined to a hand full of plants around the country all employing similar production methods. 

Contrast this to the livestock industries. There are thousands of livestock producers in Australia, farming across a massive geographical area. Ranging from tropical savannahs in northern Australia to temperate improved pasture systems in the south. Arid pastoral systems in the centre to feedlots in our grain growing regions.

The nature of these systems means that the factors of production vary so greatly from one place to another, from the feed the animals eat, their genetics and the management intensity. Some producers may only see their animals once a year while others milk their cows twice a day. In addition, we are dealing with a complex biological system, the animal! Anyone with a pet at home can no doubt appreciate these can be difficult to manipulate and change. Therefore, the solutions cannot be singular in approach.  

What are some of the mitigation options?

Many of you may have heard of seaweed being fed to cattle to lower their greenhouse gas emissions. This is a very promising technology that aims to change how the gut microbiome works. However, it may only be applicable to intensively managed herds such as in feedlots or dairies. There is also diverse suite of other options being developed ranging from water treatments, anti-methanogenic pasture species, genetic improvement and planting trees on farms to offset emissions. Many are novel and as of yet not well understood at scale or well costed at either a farm, regional or industry level. 

What is clear is that we are going to need a portfolio of approaches to tackle the issue. However, not every farm is going to have access to a full suite of options. Some farms will have access to more options because of their smaller size, intensive management, climate, higher value products and proximity to labour and will likely find the task of mitigating their methane emissions easier than larger, drier, or more remote producers.  

In the Towards Net Zero team, we are working to understand the applicability and cost of such mitigation technologies across the diverse production systems of Australia. We are addressing questions like how much of the livestock industries methane emissions can be mitigated right now and where? Where do we currently lack options and how big is that problem going to be? And importantly what can be done to address that?