Decarbonisation Technology May 2022 Issue

the main cause of higher atmospheric methane concentrations, although changes impacting the flux between emissions and sinks may also be a factor. Globally, the main anthropogenic sources are agriculture at 45%, followed by fossil fuel production and use (coal, oil, and natural gas) at 24%, waste at 20%, and smaller amounts from burning of biomass and biofuels, residential, and industrial emissions (see Figure 2 ). However, the ranking of anthropogenic emissions changes in different regions of the world. Emissions from paddy fields reflect the importance of rice cultivation in Asia. Similarly, the increased reliance on coal for power in Asia results in a higher contribution from coal relative to oil and gas, whereas in Europe, rice and coal rank lower than emissions from livestock and gas (Saunois, et al. , 2020). Reducing methane emissions from agriculture and waste The UN Climate and Clean Air Coalition (CCAC) estimates that known techniques and management practices could reduce emissions by between 21 and 40% of that needed for agriculture to contribute to its share of methane emissions reductions. Farmers will readily adopt new practices if they can realise tangible benefits in terms of greater productivity, lower input costs, or more sustainable yields through better resource management. The UN International Methane Observatory in its theory of change aims to catalyse action by plant managers (IMEO, 2021a). Whilst this

comment is in relation to emissions from oil and gas operations, it is equally valid, but with less global governance, more problematic, in the context of reducing methane from agriculture. CCAC’s Agriculture Initiative includes four programmes targeting reductions in methane emissions (CCAC, 2019):  Rice methane Reducing methane from rice cultivation Rice is the staple food for 3 billion people, providing one-fifth of calories consumed worldwide. Rice cultivation is responsible for 9% of anthropogenic methane emissions (IRRI, 2021a). Flooded rice paddies are ideal anaerobic environments for methane-producing microbes that feed on decomposing organic matter, a process known as methanogenesis (Drawdown, 2019a). Alternate Wetting and Drying practices, originally developed to save water, have been found to decrease methane emissions. CCAC estimates that this could reduce methane emissions from paddy fields by over 30% by 2030 (CCAC, 2022a). Project Drawdown extends this out to 2050 and estimates that mid-season drainage alone can reduce methane emissions by 70% (Drawdown, 2019a). The International Rice Research Institute (IRRI) “Paddy Rice Component” provides technical and policy guidance for national governments (IRRI, 2021b). The programme will address major constraints to methane mitigation by identifying  Livestock methane  Manure methane  Bioenergy methane

OECD countries

-11%

Mixed dairy OECD Fat supplementation 2.1-2.3% Manure management 8.9%

-47.5%

South America

Beef cattle Improved feed quality 25.7% Improved fertility and reduced mortality 21.8% Small ruminants Improved fertility and reduced mortality 2.65% Improved feed quality 1.85% Mixed dairy Improved feed quality 2.2-9% Improved fertality and reduced mortality 0.6-1.9% Commercial pigs Improved fertility and reduced mortality 17.1% Manure management 15.4%

West Africa

-4.5%

East Africa

-2.8-10.9%

South East Asia

South Asia

-38%

-20-28%

Dairy cattle Improved feed quality 23.4% Improved fertality and reduced mortality 3.3%

Source: (CCAC, 2019 )

Figure 3 Methane mitigation potential for the livestock sector