Agriculture solutions

Reducing methane and black carbon emissions from agriculture

Agriculture employs over 800 million people, the majority of whom work in smallholder farms and earn less than $2 per day. This makes them highly vulnerable to disruptions in their livelihoods and reduces their capacity to invest in and implement more sustainable practices.

Solutions for agricultural SLCP emissions are however available using existing technology. Crucially these solutions increase agricultural productivity and sustainability, protecting livelihoods and food security in the process.

Main emissions Sources

The main sources of SLCP emissions in the agriculture sector are animal husbandry, manure management, wet rice cultivation, and open burning of crop residues.

Agriculture is the largest human-derived source of methane emissions (40%). Methane is second to carbon dioxide in driving climate change. Methane is an important precursor to tropospheric ozone, an air pollutant that reduces plant productivity and crop yields, as well as harming human health.

Globally, agricultural burning is also responsible for around 5% of black carbon emissions. Black carbon negatively affects agriculture by disrupting weather patterns, rainfall and ecosystems due to its localised effects of absorbing heat, blocking sunlight and increasing plant surface temperatures.

Enteric fermentation

Methane Black carbon

Enteric fermentation is a natural part of the digestive process in ruminant animals such as cattle, sheep, goats, and buffalo. Enteric methane emissions from ruminant animals raised for their meat and milk account for as much as 30% of global anthropogenic methane emissions, and factors such as feed quality, animal size, and environmental temperature will increase the amount of methane an animal produces if left unchecked.

Animal manure

Methane
Manure, which is often disposed of in piles, slurries or lagoons, leads to significant emissions of methane, as well as environmental degradation, negative health impacts, and the loss of valuable nutrients that could be added to soil. Proper treatment of manure can be expensive and labor-intensive for farmers, limiting the adoption of improved management practices, especially for farmers with little cropland.

Rice production

Methane
Paddy rice is grown in warm, waterlogged soil. When continually flooded this soil provides ideal conditions for microbes that produce large amounts of methane. This process is responsible for about 30 million tonnes, or 8% of global emissions, each year.

Crop burning

Black carbon
Responsible for 5% of global black carbon emissions, open burning from the agro-forestry sector, including stubble and pastureland burning and use of fire to clear fallow lands, is the single largest source of black carbon. In some regions open burning comprises up to 30% of black carbon emissions.

Solutions

To stay within the limit of 1.5 degrees of warming set by the Paris Agreement, methane emissions in the agriculture sector need to be cut by between 20-25% at minimum. The measures required to do so are already known and available.

Given agriculture’s crucial role in food security and employment, and the low socio-economic status of most agricultural workers, it is crucial that interventions in agriculture do not come at the cost of productivity or food security. State and non-state actors must also invest in supporting agricultural workers to enhance the quality of their practices and technology usage.

The CCAC focuses on measures to reduce emissions from paddy rice cultivation, enteric fermentation, manure management, and the burning of crop residues. Existing interventions in beef cattle production – largely in feed and animal health improvements – have proven effective at reducing enteric methane emissions by between 40% and 70%. In dairy cattle, methane emissions can be reduced by 38%, while commercial piggery emissions can be reduced by between 20% - 28%.

In rice production, alternative growing methods which allow the top layer of soil to dry sufficiently during a growing season can reduce methane emissions by 6-9 mt/yr reductions (20-30%). Efficient nitrogen use and application of organic inputs to dry soil can further reduce methane emissions.

Anaerobic digestion of animal manure also has the potential to capture valuable methane gas and create rich fertilisers which can be recycled into energy supplies and farm inputs. Further, different species of ruminants produce different levels of methane through their digestive systems. Selective breeding of sheep and cattle can reduce enteric fermentation emissions by as much as 20%.

To reduce agricultural black carbon, the CCAC focuses on eliminating open burning by raising awareness about proven crop residue management strategies and alternative uses of crop residues for the most frequently burned crops (e.g. maize, millet, rice, wheat and sugar cane).

Finally, three behavioural changes--reduced food waste and loss, improved livestock management, and adoption of healthier diets--have the highest potential to reduce agricultural methane emissions by 65–80 Mt/yr over the next few decades.

What Can Be Done

Optimize livestock production efficiency to reduce methane emission intensity through breeding practices, herd and animal health management, and feed and pasture management
Control methane emissions from rice cultivation through adoption of direct dry seeding rice varieties, intermittent aeration of continuously flooded rice paddies, and rice straw
Promote composting, anaerobic digestion, and solid-liquid separation to control nitrous oxide and methane emissions from livestock manure
Promote integrated nutrient management—combining precision application, enhanced-efficiency fertilizers, and soil-health practices—to improve nitrogen-use efficiency, sustain yields, and cut nitrous oxide emissions from fertilizer use
Eliminate open burning in agriculture through regulation, promotion of alternative residue uses, adoption of no-till practices, and farmer education
In countries with high consumption rates of animal sourced foods, promote consumer awareness of healthy diets according to WHO guidelines and their link to environmental sustainability

Benefits

Reducing methane and black carbon emissions from agriculture is essential to the sustainability of the agriculture sector. In a warming planet, agricultural crops and other plants will face increased heat stress and vulnerability to extreme weather events. Methane and black carbon are intense climate warmers.

Not only do reductions in methane and black carbon promise reduced global warming, but they also enhance plant and ecosystem productivity. At present up to 15% of staple crop yields are lost each year due to the toxic effects of black carbon and tropospheric ozone – methane is responsible for around 50% of tropospheric ozone.

Tropospheric ozone and black carbon also damage human health in regions of concentration. Tropospheric ozone damages respiratory systems and causes chronic disease. Black carbon is a fine particulate matter pollutant (PM2.5) which enters the lungs and introduces other chemicals into the bloodstream, causing chronic and acute illness. Each year over 7 million premature deaths are attributed to air pollution driven by black carbon, tropospheric ozone and other pollutants.

What we do

On methane, the Coalition supports work to reduce emissions from wet rice cultivation and livestock production. Solutions we promote in our projects include improved animal feeding and health, improved manure management, and alternate wetting and drying of rice paddy fields.

This includes several projects implementing policy actions and technology interventions in high methane-emitting sites in South Asia, East Asia, Sub-Saharan Africa and South America.

On black carbon, the CCAC is also supporting the development of replicable and scalable "no burn" alternatives tailored to local environments and crops. This includes application of alternatives to main open burning in targeted regions, and on-the-ground demonstrations of no-burn practices to help educate local communities.

The CCAC also supports data gathering through actions such as satellite monitoring of fires and their related pollutant emissions, as well as engaging policy advancement at the regional and national levels through high-level political engagement.