Stop the metric fuss and get on with methane reducing: scientists

Ultimately, it will be this work which guarantees the livestock industry's social licence.

This case has been made by two leading climate scientists, professors Mark Howden and Richard Eckard.

Having a universally agreed metric for measuring greenhouse gas emissions is fundamental to meeting global climate change goals and the world has 'explicitly adopted' Global Warming Potential 100, or GWP-100, via the Paris Agreement, they say.

Professor Eckard: "Arguments about metrics is just moving deck chairs around on the Titanic and it delays focused research on cost-effectively reducing methane emissions.

"In the end, regardless of metric, zero methane is zero methane."

Professor Howden: "Arguing for longer and longer about metrics just puts the brakes on the necessary action."

The scientists, speaking in a well-attended webinar hosted by Farmers For Climate Action, outlined key arguments for why GWP-100 was the most appropriate metric for assessing the impact of the livestock sector's methane emissions on global temperatures.

Prof Howden, director of the Institute for Climate, Energy and Disaster Solutions at the Australian National University and vice chair of the United Nations' Intergovernmental Panel on Climate Change, began with a description of how methane was affecting the climate.

Methane in the atmosphere was at record concentrations and going up at record levels, he said.

Contrary to some claims, it does not cool the climate - it's a GHG and every emission of methane makes the earth warmer than it would be otherwise.

It is the second biggest human-caused GHG, with about a third of the radiative forcing of carbon dioxide and three times that of nitrous oxide.

Prof Howden said while science's understanding of methane was not complete, it was more than good enough to allow for sensible decisions about policies and preferences for emission reductions.

Carbon dioxide is the prime driver of climate change, so there is a need to put methane into the context of CO2.

No single metric answers every question.

However, the Paris Agreement has adopted the GWP-100 metric and that is now embedded into policies and programs.

"It provides a common basis for the rapid progress that is needed if we are to avoid the impacts and costs of climate change," Prof Howden said.

Methane can come from fossil-based sources or biological sources, such as livestock.

The latter temporarily removes a carbon dioxide molecule from the atmosphere in its formation, so when it breaks down it mostly returns to the atmosphere as CO2.

"This temporary reduction of CO2 is why the GWP-100 for methane from biological sources is slightly lower - that biological source is already taken into account in the calculations of GWP-100," Prof Howden said.

More than 150 countries have now joined the Global Methane Pledge to reduce methane emissions by at least 30 per cent from 2020 levels by 2030.

"What we need is absolute reductions in methane emissions if we are to achieve the Paris Agreement goals," Prof Howden said.

One of the biggest barriers in international climate negotiations has been ensuring equity between the wealthy versus emerging economies, Prof Eckard, professor of Sustainable Agriculture at the University of Melbourne and director of the Primary Industries Climate Challenges Centre, said.

The alternate metric being pushed by some in Australia's cattle industry, GWP*, assigns zero to constant methane emissions but heavily penalises industry growth.

It assigns different values to the same amounts of methane.

In effect, it suits a mature livestock environment but disadvantages emerging economies form achieving food security or wealth through livestock, according to Prof Eckard.

Under this metric, a Kenyan farmer doubling his production by going from one cow to two would compare unfavourably to a US dairy farm with 20,000 cows that does not expand at all.

The other problem Prof Eckard outlined was that many multinational supply chains with net zero goals, like Fonetra, Mondelez, Kellogss, Inghams and Cargill have adopted GWP-100.

"If we conveniently choose another metric we will find we don't meet the standards of major supply chains," he said.

Further, doubling the value of red meat sales by 2030 - a major industry goal - can only be achieved by increasing the national herd, with analyst estimates putting the necessary increase at circa 10 million head.

Under GWP*, those new animals will deliver a much bigger global warming potential to Australia's industry than GWP-100, Prof Eckard said.