The Impact of Livestock Agriculture on Climate ChangeAgriculture 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.

The Impact of Livestock Agriculture on Climate Change

The Intergovernmental Panel on Climate Change (IPCC) estimates that, as at 2005, agricultural emissions of methane (CH4) and nitrous oxide (N2O) were responsible for around 12 per cent of all anthropogenic (human-sourced) greenhouse gas emissions1.

The livestock sector contributes between 25 and 40 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 10 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 20 per cent of all terrestrial animal biomass on the planet

There is robust scientific evidence that the climate is changing, and that most of the warming observed over the past 50 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.

NZAGRC FACTSHEET 1

“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.

1. using 100-year Global Warming Potentials to compare emissions of different gases

Page 2

Energy supply, 25.9%

Transport, 13.1%

Residential and

commercial buildings,

7.9% Industry, 19.4%

Agriculture, 13.5%

Forestry, 17.4%

Waste and wastewater,

2.8%

Estimated contribution of different sectors to global greenhouse gas emissions related to human activities, for 2005. Emissions from agriculture include loss of soil carbon, but deforestation is counted under forestry. Source: IPCC, 2007.

Estimated direct global emissions from different livestock-related activities, in gigatonnes of CO2-equivalent. Data from Steinfeld et al., 2006, FAO. Data do not include emissions of CO2 related to land clearance, estimated at 2.4 Gt CO2-eq.

Contribution from agriculture and individual livestock sources to global greenhouse gas emissions

– produce almost 100 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 N20

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 (CO2) 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 CO2 could account for about nine per cent of all anthropogenic CO2 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.”

fossil fuel use, 0.16

soil carbon losses, 0.04

enteric fermentation, 1.8

manure management

(methane), 0.37 N fertiliser application, 0.1 indirect fertiliser

emissions, 0.1

leguminous feed cropping, 0.2

manure management

(nitrous oxide), 0.33

manure deposition, 0.84

indirect manure emissions, 0.62

P.K.Thornton (2010)

Page 3

A Growing Appetite

Trends in meat and dairy product consumption

Total meat consumption in the developing world tripled between 1980 and 2002, to more than 130 million tonnes. As a burgeoning global population increasingly demands protein-rich foods, that consumption is projected to more than double again, to over 300 million tonnes by 2050.

Even in the developed world, with its nearly static population, meat consumption is expected to continue to grow from just over 100 million tonnes in 2002 to about 126 million tonnes in 2050.

Meanwhile, global milk consumption is tipped to almost double from about 500 million tonnes today to almost 900 million tonnes in 2050.

Based on past trends, that would drive three-fold increases in nitrogen and animal manure fertiliser use. As a result, by 2050, agricultural N2O emissions are projected to increase by between 30 and 60 per cent, while livestock expansion is expected to boost methane emissions by 20 to 60 per cent.

As a consequence, agricultural emissions of CH4 and N2O 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 reported and projected consumption per capita of meat (top) and dairy products (bottom), from 1970 to 2050. Meat is expressed in kg carcass weight; dairy products is expressed in fresh milk equivalent, excluding butter. Source: FAO, 2006.

0

20

40

60

80

100

120

1970 1980 1990 2000 2030 2050

Mea

t Con

sum

ptio

n

(kg

per p

erso

n pe

r yea

r)

Year

1970 1980 1990 2000 2030 2050 Year

0

50

100

150

200

250

Dai

ry P

rodu

ct C

onsu

mpt

ion

(F

resh

milk

equ

ival

ent,

litre

s pe

r per

son

per y

ear)

Sub-Saharan Africa

Near East / North Africa

Latin America and Caribbean

South Asia

East Asia

Industrial countries

Transition countries

Developing countries

Page 4

400

800

1200

1600

2000

1000 1200 1400 1600 1800 2000

Met

hane

con

cent

ratio

n (p

arts

per

bill

ion

by v

olum

e)

Year

Methane – A window of opportunity

Increases in CH4 concentration since 1000 A.D.

“Collectively, human activities are thought to be responsible for most of the global warming already observed over the past half century”

Analysis of air bubbles trapped in ice sheets tells us that methane is more abundant now than at any time in the last 850,000 years. Since the industrial revolution, global average atmospheric concentrations have increased by 150 per cent, from around 700 parts per billion by volume (ppbv) to 1745 ppbv in 1998.

According to the IPCC, the warming effect from those increased CH4 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 2006, prompting speculation that emissions had stopped increasing. However, since 2006, 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 CH4 concentrations could increase by another 10 to 50 per cent by 2050.

Methane is a much more potent greenhouse gas than carbon dioxide, but it is relatively short-lived in the atmosphere – after 12 years, about 60 per cent of that originally emitted has disappeared. This means that, if methane emissions were held constant, concentrations of CH4 in the atmosphere would soon flatten out. By contrast, even if CO2 emissions were somehow stabilised, atmospheric concentrations would still continue to increase, because a fraction of every CO2 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

Methane concentrations from 1000 AD to present. Methane concentrations from 1000 AD to present, with expanded section showing data points since 1978. Data from ice cores (Etheridge et al., 1998, J. Geophys. Res, 103, 15,979-15,993) and the US National Oceanic and Atmospheric Administration (NOAA Earth System Research Laboratory global air sampling network.(http://www.esrl.noaa.gov/gmd/).

Page 5

0

1

2

3

1800 1850 1900 1950 2000

Contributions to the total warming effect on the global climate from methane, nitrous oxide and carbon dioxide from 1800 to 2010. Source: emissions from Meinshausen et al., 2011, Climatic Change 109(1-2), 213-241 and climate model calculations.

“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”

Combined warming effect from increasing CH4, N2O and CO2 concentrations

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

effect much more quickly than the warming effect from CO2.

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 N2O and CH4, and/or through efforts to increase the absorption and storage of CO2 in agricultural soils and through agroforestry.

War

min

g ef

fect

(rad

iativ

e fo

rcin

g) fr

om in

crea

sing

gr

eenh

ouse

gas

con

cent

ratio

ns in

the

atm

osph

ere

(W/m

2 )

Carbon dioxide (CO2)

Nitrous oxide (N2O)

Methane (CH4)

Page 6

Nearly half of New Zealand’s greenhouse emissions come from agriculture – 33.7 million tonnes of carbon dioxide equivalent (Mt CO2-e) in 2010 – and 95 per cent of those come from the pastoral sector.

In 2010, the latest year for which figures are available, the country’s estimated total greenhouse gas emissions had increased by 19.8 per cent above 1990 levels. On the back of an expanding national dairy herd and higher nitrogen fertiliser application, agricultural emissions are estimated to have increased by almost 10 per cent – 2.89 Mt CO2-e – above the 1990 level of 30.85 Mt CO2-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 2050. 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.

New Zealand – An unusual developed country

Percentage contribution of different sectors to New Zealand’s gross greenhouse gas emissions in 2010. Source: MfE, 2012.

Trends in emissions from different sectors in New Zealand, from 1990 to 2010. Source: MfE, 2012.

Trends in emissions from different sectors in New Zealand

Contributions from different sectors to New Zealand's gross emissions

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

1990 1995 2000 2005 2010

Energy

Industrial Processes

Agriculture

Waste

GH

G e

mis

sion

s in

kt C

O2-e

quiv

alen

t

Year

Energy, 43%

Industrial Processes, 7%

Solvent and Other Product

Use, 0%

Agriculture, 47%

Waste , 3%

Solvent and Other Product

Use, ~0%

“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”

Page 7

Tel +64 6 351 8334 Fax +64 6 351 8333 Email enquiry@nzagrc.org.nz

www.nzagrc.org.nz

Grasslands Research Centre Tennent Drive Private Bag 11008 Palmerston North, 4442 New Zealand

Further readingIPCC, 2007: Climate Change 2007: 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, 2007: Climate Change 2007: 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, 2012: Emissions Database for Global Atmospheric Research (EDGAR). European Commission (Website: http://edgar.jrc.ec.europa.eu/index.php).

World Bank, 2009: Minding the Stock: Bringing Public Policy to Bear on Livestock Sector Development. Report No. 44010-GLB. The World Bank, Washington, DC, 74 pp.

FAO, 2002: World agriculture: towards 2015/2030. Summary report. Food and Agriculture Organisation, Rome, Italy, 97 pp.

Steinfeld, H., et al., 2006: Livestock’s Long Shadow. Environmental issues and options. Food and Agriculture Organisation, Rome, Italy, 389 pp.

FAO, 2006: World agriculture: towards 2030/2050. Prospects for food, nutrition, agriculture and major commodity groups. Interim report. Food and Agriculture Organisation, Rome, Italy.

FAO, 2012: The LEAD (Livestock, Environment and Development) Initiative. Food and Agriculture Organisation (Website: http://www.fao.org/agriculture/lead/en/), Rome, Italy.

Cox, P.M., H.A. Jeffery, 2010: Methane radiative forcing controls the allowable CO2 emissions for climate stabilization. Current Opinion in Environmental Sustainability 2(5-6), 404-408.

Kemfert, C., W.-P. Schill (2009) An Analysis of Methane Mitigation as a Response to Climate Change. Copenhagen Consensus Center, Copenhagen Business School, Denmark. pp39.

Moss, R.H., et al., 2010: The next generation of scenarios for climate change research and assessment. Nature 463(7282), 747-756.

Shindell, D., et al., 2012: Simultaneously Mitigating Near-Term Climate Change and Improving Human Health and Food Security. Science 335(6065), 183-189.

Stehfest, E., et al., 2009: Climate benefits of changing diet. Climatic Change. 95(1), 83-102.

Thornton, P.K., 2010: Livestock production: recent trends, future prospects. Philosophical Transactions of the Royal Society B: Biological Sciences 365(1554), 2853-2867.

MfE, 2012: New Zealand’s Greenhouse Gas Inventory 1990–2010. Report ME 1095 Submitted to the United Nations Framework Convention on Climate Change. Ministry for the Environment, Wellington, 408 pp.

Published November 2012