The Impact of Livestock Agriculture on Climate Change

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1 NZAGRC FACTSHEET 1 The Impact of Livestock Agriculture on Climate Change The Impact of Livestock Agriculture on Climate Change Agriculture is part of a complex social, economic and environmental global dynamic system. It feeds more than seven billion people, and underpins economic development and poverty alleviation over much of the world. It is a major source of greenhouse gases, yet stands to be impacted both directly and indirectly by climate change itself. With a growing global population to feed, it is vital that agricultural production grows but not its environmental impacts. There is robust scientific evidence that the climate is changing, and that most of the warming observed over the past 5 years is due to increasing greenhouse gas concentrations from human activities. This fact sheet summarises why, and how, livestock agriculture contributes to climate change, and why limiting the projected global increase in those emissions is seen as a key component of dealing with climate change. The Intergovernmental Panel on Climate Change (IPCC) estimates that, as at 25, agricultural emissions of methane (CH 4 ) and nitrous oxide (N 2 O) were responsible for around 12 per cent of all anthropogenic (human-sourced) greenhouse gas emissions 1. The livestock sector contributes between 25 and 4 per cent of all anthropogenic methane emissions the biggest single source. Most of that comes from the stomachs of ruminant animals, where bacteria break down cellulose in the absence of oxygen; a process called enteric fermentation. Some 1 per cent of livestock methane is produced from anaerobic manure storage, with still smaller emissions from animal manure deposited directly onto soils by grazing animals. The United Nations Food and Agriculture Organisation (FAO) has calculated that the world s 1.5 billion cattle and buffalo, 1.8 billion sheep, goats and other small ruminants, and almost one billion pigs together constituting 2 per cent of all terrestrial animal biomass on the planet 1. using 1-year Global Warming Potentials to compare emissions of different gases We need to develop agriculture that is climate smart generating more output without the accompanying greenhouse gas emissions Prof Sir John Beddington, UK government Chief Scientific Advisor.

2 produce almost 1 million tonnes of methane emissions every year. Nitrous oxide is emitted directly from soils when nitrogen-rich livestock urea and faeces, or nitrogen contained in synthetic fertilisers, is broken down by soil bacteria. Almost six million tonnes of N 2 are produced annually across the globe through urine from managed livestock and fertiliser use, constituting more than half of all anthropogenic nitrous oxide. Agriculture also emits carbon dioxide (CO 2 ) through land clearance, loss of soil carbon, feed crop production and energy use. Precise figures depend on the accounting parameters used, but estimates by the FAO indicate that these sources of CO 2 could account for about nine per cent of all anthropogenic CO 2 emissions, mainly from land clearance. Livestock products contribute 17 per cent to kilocalorie consumption and 33 per cent to protein consumption globally, but there are large differences between rich and poor countries. P.K.Thornton (21) Contribution from agriculture and individual livestock sources to global greenhouse gas emissions Residential and commercial buildings, 7.9% Industry, 19.4% Transport, 13.1% Energy supply, 25.9% Forestry, 17.4% Agriculture, 13.5% Waste and wastewater, 2.8% manure deposition,.84 manure management (nitrous oxide),.33 indirect manure emissions,.62 fossil fuel use,.16 leguminous feed cropping,.2 N fertiliser indirect fertiliser application,.1 emissions,.1 soil carbon losses,.4 enteric fermentation, 1.8 manure management (methane),.37 Estimated contribution of different sectors to global greenhouse gas emissions related to human activities, for 25. Emissions from agriculture include loss of soil carbon, but deforestation is counted under forestry. Source: IPCC, 27. Estimated direct global emissions from different livestock-related activities, in gigatonnes of CO 2 -equivalent. Data from Steinfeld et al., 26, FAO. Data do not include emissions of CO 2 related to land clearance, estimated at 2.4 Gt CO 2 -eq. Page 2

3 A Growing Appetite Total meat consumption in the developing world tripled between 198 and 22, to more than 13 million tonnes. As a burgeoning global population increasingly demands protein-rich foods, that consumption is projected to more than double again, to over 3 million tonnes by 25. Even in the developed world, with its nearly static population, meat consumption is expected to continue to grow from just over 1 million tonnes in 22 to about 126 million tonnes in 25. Meanwhile, global milk consumption is tipped to almost double from about 5 million tonnes today to almost 9 million tonnes in 25. Based on past trends, that would drive three-fold increases in nitrogen and animal manure fertiliser use. As a result, by 25, agricultural N 2 O emissions are projected to increase by between 3 and 6 per cent, while livestock expansion is expected to boost methane emissions by 2 to 6 per cent. As a consequence, agricultural emissions of CH 4 and N 2 O are, and will remain, a significant part of the global greenhouse gas inventory, and contribute to the total warming effect from greenhouse gases. Trends in meat and dairy product consumption Meat Consumption (kg per person per year) Dairy Product Consumption (Fresh milk equivalent, litres per person per year) Sub-Saharan Africa Latin America and Caribbean East Asia Transition countries Industrial countries Developing countries Near East / North Africa South Asia Trends in reported and projected consumption per capita of meat (top) and dairy products (bottom), from 197 to 25. Meat is expressed in kg carcass weight; dairy products is expressed in fresh milk equivalent, excluding butter. Source: FAO, 26. Page 3

4 Methane A window of opportunity Analysis of air bubbles trapped in ice sheets tells us that methane is more abundant now than at any time in the last 85, years. Since the industrial revolution, global average atmospheric concentrations have increased by 15 per cent, from around 7 parts per billion by volume (ppbv) to 1745 ppbv in According to the IPCC, the warming effect from those increased CH 4 concentrations is responsible for roughly a fifth of the total warming effect from all human activities. Collectively, human activities are thought to be responsible for most of the global warming already observed over the past half century. Further increases in greenhouse gas concentrations are expected to result in even greater climate changes over the 21st century, especially if no action is taken to reduce emissions. Atmospheric methane concentrations levelled off between 1996 and 26, prompting speculation that emissions had stopped increasing. However, since 26, concentrations have risen again, for reasons which are not immediately clear. Some studies point to a warming Arctic starting to release methane stored naturally in wetlands and permafrost. Based on projected emission trends from human activities, global CH 4 concentrations could increase by another 1 to 5 per cent by 25. Methane is a much more potent greenhouse gas than carbon dioxide, but it is relatively short-lived in the atmosphere after 12 years, about 6 per cent of that originally emitted has disappeared. This means that, if methane emissions were held constant, concentrations of CH 4 in the atmosphere would soon flatten out. By contrast, even if CO 2 emissions were somehow stabilised, atmospheric concentrations would still continue to increase, because a fraction of every CO 2 emission remains in the atmosphere for many thousands of years. Given those differences, it is sometimes argued that, so long as livestock methane emissions remain constant, they are Collectively, human activities are thought to be responsible for most of the global warming already observed over the past half century Increases in CH 4 concentration since 1 A.D. 2 Methane concentration (parts per billion by volume) Methane concentrations from 1 AD to present. Methane concentrations from 1 AD to present, with expanded section showing data points since Data from ice cores (Etheridge et al., 1998, J. Geophys. Res, 13, 15,979-15,993) and the US National Oceanic and Atmospheric Administration (NOAA Earth System Research Laboratory global air sampling network.( Page 4

5 Not acting to tackle methane emissions would require even greater and more rapid reductions of other greenhouse gases to achieve the goal of limiting warming to 2 C not adding to the problem of warming. Therefore, the reasoning goes, there is no need for agriculture to reduce its methane emissions. However, this overlooks a number of realities. Methane concentrations have risen significantly since the industrial revolution, and their increased warming effect is already contributing to climate change. Methane concentrations are expected to continue rising as emissions from livestock production rapidly increase, and will continue to add to warming caused by human activities overall. Scientific studies, as assessed by the IPCC, agree that greenhouse gas emissions need to be reduced significantly overall to meet the world s stated aim of constraining global warming to no more than 2 C. Not acting to tackle methane emissions would require even greater and more rapid reductions of other greenhouse gases to achieve that goal. Methane s short atmospheric life span means that any emission cuts would reduce its warming Combined warming effect from increasing CH 4, N 2 O and CO 2 concentrations Warming effect (radiative forcing) from increasing greenhouse gas concentrations in the atmosphere (W/m 2 ) Carbon dioxide (CO 2 ) Nitrous oxide (N 2 O) Methane (CH 4 ) Contributions to the total warming effect on the global climate from methane, nitrous oxide and carbon dioxide from 18 to 21. Source: emissions from Meinshausen et al., 211, Climatic Change 19(1-2), and climate model calculations. effect much more quickly than the warming effect from CO 2. Livestock are a dominant source of methane from human activities. Limiting emissions from livestock, without compromising food security, is therefore clearly an important part of any international effort to limit GHG emissions overall, and their effect on the climate system. In turn, reducing the rate and magnitude of climate change would help strengthen global food security while easing the risks to farmers livelihoods from changing weather patterns. Developing solutions and tools to reduce agricultural emissions, without compromising food security, is therefore a key element of climate change strategy, not just globally, but also for New Zealand with its large livestock industry. These solutions may take the form of improved management and new technologies to reduce emissions of N 2 O and CH 4, and/or through efforts to increase the absorption and storage of CO 2 in agricultural soils and through agroforestry. Page 5

6 New Zealand s unique emissions profile for a developed country and the pivotal place of agriculture in the national economy create an urgent need to reduce livestock emissions New Zealand An unusual developed country Contributions from different sectors to New Zealand's gross emissions Nearly half of New Zealand s greenhouse emissions come from agriculture 33.7 million tonnes of carbon dioxide equivalent (Mt CO 2 -e) in 21 and 95 per cent of those come from the pastoral sector. Waste, 3% Energy, 43% In 21, the latest year for which figures are available, the country s estimated total greenhouse gas emissions had increased by 19.8 per cent above 199 levels. On the back of an expanding national dairy herd and higher nitrogen fertiliser application, agricultural emissions are estimated to have increased by almost 1 per cent 2.89 Mt CO 2 -e above the 199 level of 3.85 Mt CO 2 -e. New Zealand s unique emissions profile for a developed country and the pivotal place of agriculture in the national economy create an urgent need to reduce livestock emissions, if the country is to meet the goal of halving its greenhouse gas emissions by 25. The eventual participation of the agriculture sector in New Zealand's Emissions Trading Scheme also signals future economic benefits to farmers from reducing emissions, but costs if no action is taken. The Government recently announced its intent to delay the entry of agriculture into the scheme. Livestock emissions are growing in many parts of the world. Therefore, collaborative international research to develop sustainable options to reduce emissions, while improving or at least maintaining animal productivity, are a key part of New Zealand s response. Separate NZAGRC fact sheets will detail current options and research activities to develop new technologies and approaches to reduce greenhouse gas emissions, and to increase soil carbon storage. Percentage contribution of different sectors to New Zealand s gross greenhouse gas emissions in 21. Source: MfE, 212. Trends in emissions from different sectors in New Zealand GHG emissions in kt CO 2 -equivalent 4, 35, 3, 25, 2, 15, 1, 5, Agriculture, 47% Solvent and Other Product Use, Use, ~% Energy Industrial Processes Agriculture Waste Industrial Processes, 7% Trends in emissions from different sectors in New Zealand, from 199 to 21. Source: MfE, 212. Page 6

7 Further reading IPCC, 27: Climate Change 27: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK. IPCC, 27: Climate Change 27: Mitigation of Climate Change. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK. European Commission Joint Research Centre, Netherlands Environmental Assessment Agency, 212: Emissions Database for Global Atmospheric Research (EDGAR). European Commission (Website: World Bank, 29: Minding the Stock: Bringing Public Policy to Bear on Livestock Sector Development. Report No. 441-GLB. The World Bank, Washington, DC, 74 pp. FAO, 22: World agriculture: towards 215/23. Summary report. Food and Agriculture Organisation, Rome, Italy, 97 pp. Steinfeld, H., et al., 26: Livestock s Long Shadow. Environmental issues and options. Food and Agriculture Organisation, Rome, Italy, 389 pp. FAO, 26: World agriculture: towards 23/25. Prospects for food, nutrition, agriculture and major commodity groups. Interim report. Food and Agriculture Organisation, Rome, Italy. FAO, 212: The LEAD (Livestock, Environment and Development) Initiative. Food and Agriculture Organisation (Website: fao.org/agriculture/lead/en/), Rome, Italy. Cox, P.M., H.A. Jeffery, 21: Methane radiative forcing controls the allowable CO 2 emissions for climate stabilization. Current Opinion in Environmental Sustainability 2(5-6), Kemfert, C., W.-P. Schill (29) An Analysis of Methane Mitigation as a Response to Climate Change. Copenhagen Consensus Center, Copenhagen Business School, Denmark. pp39. Moss, R.H., et al., 21: The next generation of scenarios for climate change research and assessment. Nature 463(7282), Shindell, D., et al., 212: Simultaneously Mitigating Near-Term Climate Change and Improving Human Health and Food Security. Science 335(665), Stehfest, E., et al., 29: Climate benefits of changing diet. Climatic Change. 95(1), Thornton, P.K., 21: Livestock production: recent trends, future prospects. Philosophical Transactions of the Royal Society B: Biological Sciences 365(1554), MfE, 212: New Zealand s Greenhouse Gas Inventory Report ME 195 Submitted to the United Nations Framework Convention on Climate Change. Ministry for the Environment, Wellington, 48 pp. Published November 212 Grasslands Research Centre Tennent Drive Private Bag 118 Palmerston North, 4442 New Zealand Tel Fax enquiry@nzagrc.org.nz Page 7