How Does The Presence of Livestock on Land Increase Net Methane Production?

How Does The Presence of Livestock on Land Increase Net Methane Production?

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It's a hot topic, and I've just read this article that debunks the claim I'm about to make - But even though I read it, I still don't really understand it. I'm happy to change my opinion if I understand the facts.

Suppose we have a closed system, imagine a pasture in an aquarium. Light goes in, grass grows, dies, decays, is recycled, all that good stuff. I imagine the air going into the aquarium is pretty atmospheric, and the air exiting has been changed depending on the amount of CO2 that is absorbed through photosynthesis, the amount of O2 is absorbed through plant respiration, and the amount of greenhouse gasses produced from decaying plant material in the thatch/soil.

(I think I have that right - my biology education doesn't go past high school level)

Now suppose we add a cow into the mix. If anything, to me, the cow reduces net emissions while it grows because less grass decays, and is instead turned into cow. Once the cow is mature, in this closed system, it's only eating and "processing" the grass that was already part of this natural cycle of growth/decay.

Here's where I think I am possibly going wrong:

  1. Does the cow increase the amount of "decay"? Does eating the grass make it re-grow faster, thus speeding up that natural cycle?
  2. Or, does the cow output different (more harmful) greenhouse gasses than the grass would normally produce through decay?

In short, how does the cow increase emissions? It can only have eaten what has already been grown - And what has grown is doomed to someday decay and be re-released into the atmosphere anyway. I don't particularly like having contrary opinions, so help me out!

Ruminant digestion produces a lot of methane.

Cows are ruminants, and ruminants produce a LOT of methane. Sheep and goats are also ruminants but their are far fewer of them. Ruminants use methanogenic bacteria to breakdown their food, these bacteria, as there name implies release methane as a byproduct. Ruminants produce a lot more methane than other herbivores becasue of this.

Decaying grass normally produces CO2 as do many native herbivores. Cows like most herbivores only convert a very small amount of the grass they eat into cow. Herbivore digestion is not terribly efficient, not surprising the grass does not what to be easy to digest.

Farming also puts a lot more herbivore mass on a piece of land than it would normally have, further increasing the effect, that is the purpose of farming to get more out of the land than simple hunter/gathering could. This is an issue becasue methane is a FAR more effective greenhouse gas than CO2.

Feeding cattle often involves replacing existing ecosystems which high yield feed crops and this can release a lot of CO2 and/or Methane depending on the original ecosystem just from the change, but it also means that feed is now producing methane instead of CO2 it would be if eat by non-ruminants.


Source 2

Are cows the cause of global warming?

A cow does on overage release between 70 and 120 kg of Methane per year. Methane is a greenhouse gas like carbon dioxide (CO2). But the negative effect on the climate of Methane is 23 times higher than the effect of CO2. Therefore the release of about 100 kg Methane per year for each cow is equivalent to about 2’300 kg CO2 per year.

Let’s compare this value of 2’300 kg CO2: The same amount of carbon dioxide (CO2) is generated by burning 1’000 liters of petrol. With a car using 8 liters of petrol per 100 km, you could drive 12’500 km per year (7’800 miles per year).

World-wide, there are about 1.5 billion cows and bulls. All ruminants (animals which regurgitates food and re-chews it) on the world emit about two billion metric tons of CO2-equivalents per year. In addition, clearing of tropical forests and rain forests to get more grazing land and farm land is responsible for an extra 2.8 billion metric tons of CO2 emission per year!

According to the Food and Agriculture Organization of the United Nations (FAO) agriculture is responsible for 18% of the total release of greenhouse gases world-wide (this is more than the whole transportation sector). Cattle-breeding is taking a major factor for these greenhouse gas emissions according to FAO. Says Henning Steinfeld, Chief of FAO’s Livestock Information and Policy Branch and senior author of the report: "Livestock are one of the most significant contributors to today’s most serious environmental problems. Urgent action is required to remedy the situation."

Livestock now use 30 percent of the earth’s entire land surface, mostly permanent pasture but also including 33 percent of the global arable land used to producing feed for livestock, the report notes. As forests are cleared to create new pastures, it is a major driver of deforestation, especially in Latin America where, for example, some 70 percent of former forests in the Amazon have been turned over to grazing.

Soil Management

Excess nitrogen in agriculture systems can be converted to nitrous oxide through the nitrification-denitrification process. Nitrous oxide is a very potent greenhouse gas, with 310 times greater global warming potential than carbon dioxide. Nitrous oxide can be produced in soils following fertilizer application (both synthetic and organic).

As crops grow, photosynthesis removes carbon dioxide from the atmosphere and stores it in the plants and soil life. Soil and plant respiration adds carbon dioxide back to the atmosphere when microbes or plants breakdown molecules to produce energy. Respiration is an essential part of growth and maintenance for most life on earth. This repeats with each growth, harvest, and decay cycle, therefore, feedstuffs and foods are generally considered to be carbon “neutral.”

Some carbon dioxide is stored in soils for long periods of time. The processes that result in carbon accumulation are called carbon sinks or carbon sequestration. Crop production and grazing management practices influence the soil’s ability to be a net source or sink for greenhouse gases. Managing soils in ways that increase organic matter levels can increase the accumulation (sink) of soil carbon for many years.

Chapter Four - Livestock Production and Its Impact on Nutrient Pollution and Greenhouse Gas Emissions

The livestock sector provides more than one-third of human protein needs and is a major provider of livelihood in almost all developing countries. While providing such immense benefits to the population, poor livestock management can potentially provide harmful environmental impacts at local, regional, and national levels which have not been adequately addressed in many countries with emerging economies. Twenty-six percent of global land area is used for livestock production and forest lands are continuously being lost to such activities. Land degradation through soil erosion and nutrient depletion is very common across pastures and rangelands. The intensification of livestock production led to large surpluses of on-farm nitrogen and phosphorus inputs that can potentially contribute to nonpoint source pollution of water resources in many parts of the world. The sector is one of the largest sources of greenhouse gases (GHGs) contributing around 14.5% of all human-induced GHG emissions, a major driver of use and pollution of freshwater (accounting 10% anthropogenic water use) and a contributor to the loss of biodiversity. About 60% of global biomass harvested annually to support all human activity is consumed by livestock industry, undermining the sustainability of allocating such large resource to the industry. Despite the negative impacts of livestock production, opportunities exist to balance the competing demands of livestock production and the environment. These include (1) improved technologies and practices that increase livestock productivity with optimal use of land and water, (2) reorienting grazing systems to provide environmental services for water, biodiversity, carbon sequestration, and resource conservation, (3) reducing GHG emission from livestock production, and (4) an effective management strategy for efficient and sustainable use of manure in livestock production. Further research, appropriate policy development, and institutional support are important to ensure the competitiveness of the industry. Integration of crops with livestock production provides opportunities for increasing resource use efficiencies and reducing environmental pollution, making the system resilient to impacts of climate change, reducing GHG emissions from the system, enhancing soil quality and fertility, and improving water quantity and quality. Appropriate techniques for assessing and monitoring impacts of livestock production are necessary for developing strategies and making the system profitable, sustainable, and resilient. Isotopic and nuclear techniques play an important role in such assessment and monitoring.

Manure Management

A similar microbial process to enteric fermentation leads to methane production from stored manure. Anytime the manure sits for more than a couple days in an anaerobic (without oxygen) environment, methane will likely be produced. Methane can be generated in the animal housing, manure storage, and during manure application. Additionally, small amounts of methane is produced from manure deposited on grazing lands.

Nitrous oxide is also produced from manure storage surfaces, during land application, and from manure in bedded packs & lots.


Food and Agriculture Organization of the United Nations World Agriculture: Towards 2015/2030 (FAO, 2002).

Herrero, M. et al. Science 327, 822–825 (2010).

Bocquier, F. &amp Gonzalez-Garcia, E. Animal 4, 1258–1273 (2010).

Grace, D. et al. Mapping of Poverty and Likely Zoonoses Hotspots (International Livestock Research Institute, 2012).

Kenyon, F. et al. Vet. Parasitol. 164, 3–11 (2009).

Lee, M. R. F., Tweed, J. K. S., Minchin, F. R. &amp Winters, A. L. Anim. Feed Sci. Technol. 149, 250–264 (2009).

Bickell, S. L., Durmic, Z., Blache, D., Vercoe, P. E. &amp Martin, G. B. in Updates on Ruminant Production and Medicine Proc. 26th World Buiatrics Congress, Santiago, Chile (eds Wittwer, F. et al.) 317–325 (Andros Impresores, 2010).

Smith, J. et al. Anim. Front. 3, 6–13 (2013).

Otte, J. et al. Livestock Sector Development for Poverty Reduction: An Economic and Policy Perspective — Livestock's Many Virtues (FAO, 2012).

Garnett, T. Environ. Sci. Policy 12, 491–503 (2009).

Climate change: Methane emissions have gone up everywhere except Europe

US oil and gas drilling, along with agricultural production worldwide, are driving up global emissions of the potent greenhouse gas methane, two new studies show.

That marks a shift from the 2000s, when methane output from human activity came mostly from coal mines. But from 2007 through 2017, methane emissions climbed on leaks from fossil fuel operations and on food production as people around the world ate more meat.

In the United States, now the world's top oil and gas producer, increased drilling by the industry contributed most to the rise.

In South Asia, South America and Africa, growing agricultural activities such as livestock operations and farm waste caused methane levels in those regions to spike, both studies showed.

A rise over China was attributed to both agriculture and fossil fuels.

"It's more robust evidence that fossil fuels and agriculture are both equally contributing to the increase of methane contributions in the atmosphere," said co-author Ben Poulter, an environmental scientist at NASA Goddard.

The two studies — published in the journals Earth System Science Data and Environmental Research Letters — gave an update on both natural and human-driven methane sources, or what is known as the global methane budget. The last update was in 2016 and accounted for emissions up to 2012.

Methane, an invisible gas, is more efficient at trapping heat than carbon dioxide but it lingers for less time in the atmosphere.

Reducing methane emissions could help to prevent the worst impacts of climate change.

The only region shown to have lowered emissions between 2000 and 2017 was Europe.

This was likely due to lower meat consumption and stricter regulations on landfills, where decomposing garbage releases methane, said Euan Nisbet, an Earth scientist at Royal Holloway, University of London, who did not contribute to the reports.

"There are huge, juicy targets for mitigating emissions," he said.

What is carbon farming and the Emissions Reduction Fund?

The Emissions Reduction Fund is an allocation of $2.55 billion of Federal Government money to pay for carbon abatement projects.

The studies used several ways of measuring emissions, including both ground and satellite observations as well as consumption and production trends, which are good at capturing large point sources.

Harder to assess are the emissions from thousands of small farms, rice paddies and more than 1 billion head of cattle.

Identifying sources of methane is an important first step in figuring out how to bring emissions down.

For example, covering landfills and better managing methane-belching cattle could have a big effect, Professor Nesbit said. Even just spreading manure around over a field, rather than having it piled up, can help fight the formation of methane.

"There are a lot policymakers and companies can do to cut methane emissions. But in most places around the world, we aren't doing them," said environmental scientist Rob Jackson at Stanford University, a co-author on one of the new studies and chair of the Global Carbon Project.

US President Donald Trump last year proposed rolled back methane regulations to help drilling companies cut costs.

While the example of Europe cutting emissions gives some scientists hope the region can serve as a blueprint for others, the reports also serve as a warning.

"Given that these reports show that methane emissions are currently increasing globally, it does not encourage me that we will be able to reverse the trend and achieve the necessary reductions within the next decade," said study co-author Thomas Weber, from the University of Rochester in New York.

Stocking rates

Australian livestock emissions have declined since the 1990s. Although partially offset by a rise in beef cattle numbers, this decline has been driven by a fall in sheep numbers. Reducing the number of unproductive animals on a farm can potentially improve profitability and reduce greenhouse gas emissions. If productivity increases through nutritional and breeding strategies, the number of livestock can be reduced without losing the quantity of meat that is currently produced.

Strategies such as extended lactation in dairying – where cows calve every 18 months rather than annually – reduce herd energy demand by 10%, and so potentially reduce methane emissions by a similar amount. With earlier finishing of beef cattle in feedlots, slaughter weights are reached at a younger age, with reduced lifetime emissions per animal and proportionately fewer animals producing methane.

Trials involving mating replacement merino ewes at 7 months of age were successful in reducing greenhouse gas emissions by 9–12% through removing an age group of ewes that were previously not reproductive.

There is an approved methodology for improving cattle herd management to generate carbon offsets.

Case study

The Australian Government compiled case studies in the report, Solutions for waste management in regional and remote Australia. The case study of the City of Mandurah, Water Corporation and local on-farm composting operation, C-Wise, illustrates the successful recycling of 100% of the green waste and biosolids from a regional city for local economic and environmental benefit.

The technology used was based on design, simplicity, process control, cost of production, and energy and greenhouse gas savings. The process provides a technique that can be used by regional communities, feedlots, farmers and others to effectively process organic wastes.

Mandurah has a population over 65 000. All of its green waste and biosolids are recycled into organic-based fertiliser by composting on a local farm. This fertiliser is used by other farmers to build soil biology and performance at the same time as developing more resilient farming systems.

Each year, over 6000 tonnes of greenhouse gas emissions are being saved using this composting practice. The methodology has been adopted by several communities around Australia.

Land-use to solve climate change: a focus on livestock

Greenhouse gas (GHG) emissions from agriculture, forestry and other land uses (AFOLU sector) cover the 24% of global emissions, representing the second hot spot in the contribution to climate change after the energy sector.

The main drivers are CO2 emissions from deforestation, methane (CH4) emissions produced by ruminant livestock and by anaerobic fermentation of organic matter, mainly from rice crops, and nitrous oxide (N2O) emissions from fertilizer use. Thus, the land sector plays a crucial role in the contribution to climate change.

A new study lead by the CMCC Foundation explores to which extent sustainable land management options applied at small-scale rural landscape level can be a valuable solution for increasing the mitigation potential of the land sector. In particular, possible land-based mitigation options are identified to reduce and offset GHG emissions from the livestock sector that represents one of the main sources of GHG emissions of the whole agricultural sector. Although GHG emissions from the livestock sector decreased since 1990, with ?20% in Europe in 2018, they still contribute to more than 60% to the total agricultural emissions at European level.

"The land sector", explains Maria Vincenza Chiriacò, CMCC researcher and lead author of the study, "has the unique characteristic to be at the same time both a contributor to climate change and part of its solution, thanks to the carbon sink function in soils and biomass that can be enhanced by an appropriate and sustainable land management. Our proposed land-based approach consists of two consecutive steps: we assess first the GHG emissions from the livestock activities, that is carbon footprint, in a small-scale rural area, then we evaluate the mitigation potential of a set of land-use options against livestock emissions assessed in the previous step. Our aim is to understand the extent to which land-based mitigation options at small-scale landscape level can lead to carbon neutral livestock systems".

CMCC scientists developed a land-based approach by combining different methodologies, including geographic information system (GIS) elaboration, life cycle assessment (LCA) and methodologies from the Intergovernmental Panel on Climate Change (IPCC), to investigate how and how much GHG emissions from livestock activities can be decreased and compensated through carbon removals in the same area. They tested the approach on a pilot area in central Italy corresponding to a portion of the Municipality of Viterbo (Lazio region) characterized by a strong agricultural vocation, aiming at estimating the livestock GHG emissions and the mitigation potential of sustainable land-use options applied in the same small-scale rural landscape, in the immediate proximity of the livestock emissions source.

"The results", Prof. Riccardo Valentini (CMCC Foundation and University of Tuscia) says, "show the potential for a total offsetting of the livestock GHG emissions in the pilot area, indicating possible pathways for the carbon neutral livestock systems. Besides, depending on the type and intensity of the land-based mitigation options, results undermine also the possibility to even turn the system into a net carbon sink, producing negative emissions in the land sector that can significantly contribute to the global climate change mitigation targets."

"It's important to highlight", Maria Vincenza Chiriacò adds, "the idea of proximity of our land-based approach. There are already many existing mechanisms of carbon offsetting but they work on a logic of carbon compensation on a global scale, where the carbon removals usually take place in areas that are geographically far from those in which the emissions to be compensated are generated. In our study, instead, mitigation is achieved through the implementation of land-based mitigation options that reduce emissions or increase carbon sink in the immediate proximity of the livestock GHG emissions source. This, besides contributing to the global climate change mitigation targets, entails a wide-ranging improvement of the entire agro-ecosystem at local scale, providing co-benefits that involve the local rural communities as well as the local institutions and the citizens that can gain in terms of environmental co-benefits, quality of life and territorial image."

The proposed land-based approach has been recently developed in a web tool. Designed and developed by the CMCC and Istituto di Servizi per il Mercato Agricolo Alimentare (ISMEA), with the financial support of the Programme "Rete Rurale Nazionale 2014-2020", the tool is freely available online. The web tool is based on rigorous scientific information (IPCC methodology), but it's designed to be easy to use for everyone.

The platform allows Italian livestock farmers to assess the carbon footprint of their farms by compiling a simple online questionnaire that considers the main characteristics of their livestock systems. Then, they can also assess the potential of sustainable land-based options needed to reduce and compensate their livestock emissions. Therefore, the web tool will help farmers, policy makers, and other relevant stakeholders in recognizing the best options to be applied for sustainable land management in particular at small-scale rural landscape level.

CMCC researchers aim to develop in collaboration with ISMEA and the Programme "Rete Rurale Nazionale 2014-2020" a traceability system for sustainable land-use leveraging on the developed land-based approach, through a voluntary mechanism of carbon farming practices at local level, aiming at reducing and offsetting GHG emissions from the livestock activities in Italy.

Hence, this mechanism has the potential to reduce and compensate the impacts caused by livestock products, making farmers and rural systems an important target for climate change mitigation.

The land-based approach presented in this study was developed in the framework of the Programme "Rete Rurale Nazionale 2014-2020" activities thanks to a specific agreement between the CMCC Foundation Euro-Mediterranean Center on Climate Change (CMCC) and Istituto di Servizi per il Mercato Agricolo Alimentare (ISMEA), within the project Il distretto agricolo-zootecnico-forestale: un nuovo approccio territoriale per la mitigazione dei cambiamenti climatici.

Read and download the full paper (free download until February 23, 2021):
Maria Vincenza Chiriacò, Riccardo Valentini, A land-based approach for climate change mitigation in the livestock sector, Journal of Cleaner Production, Volume 283, 2021, 124622, ISSN 0959-6526,
https:/ / doi. org/ 10. 1016/ j. jclepro. 2020. 124622.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.


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