There is growing evidence that greenhouse gas emissions from human activity contribute to climate change. Many people blame modern farming practices for accelerating this - agriculture produces between 16.8 and 32.2 percent of global greenhouse gas emissions. But could agriculture also hold some solutions to climate change?

Research for Geenpeace International by the University of Aberdeen, in the UK, analyses the contribution of modern farming to human-induced climate change. The main greenhouse gases (GHGs) associated with agriculture are nitrous oxide and methane. GHG emissions from farming include direct sources, such as soil and livestock, and indirect emissions. These include fossil fuel use, fertiliser production and changes in land use, particularly the expansion of agriculture into uncultivated areas such as tropical forests.

All farming systems emit GHGs, with intensive farming producing more emissions per area, but not necessarily per unit of product. Globally, livestock are the main source of methane, and intensive animal farming also increases the demand for feed crops and synthetic fertilisers.

Economic growth in the developing world is increasing the demand for meat, as more people can afford it. The greatest increase in meat consumption has occurred in developing countries - 77 percent from 1960 to 1990. Even without these dietary changes, the growing population in developing countries is increasing the demand for food and more intensive farming.

• From 1990 to 2005, developing countries and countries in economic transition collectively showed a 32 percent increase in GHG emissions.
• By 2005, these countries were responsible for about three quarters of global agricultural emissions.
• Three sources together contribute 88 percent of this increase: methane from livestock, soil nitrous oxide emissions and biomass burning.
• Between 2001 and 2004, the rising demand for beef and high energy feed crops (especially soya) led to the deforestation of 93,700 square kilometres of rainforest in Brazil.
• Among developing countries, China and India are the main drivers behind the increased use of fertilisers and manure to meet demands for food, caused by rapid population growth.

Despite these problems, agriculture has the potential to reduce the impact of almost all its direct emissions (known as mitigation). The researchers suggest that 89 percent of agriculture’s mitigation contribution will come from soil carbon sequestration (the removal and long-term storage of carbon from the atmosphere using soil as a natural carbon sink). In the short term, the most important measure is to avoid deforestation, especially in tropical countries.

The researchers suggest other ways in which agriculture can mitigate its GHG emissions:

• avoid bare soil and rotate crops with legumes such as peas and beans - these fix nitrogen in the soil and reduce reliance on fertilisers.
• reduce tillage (preparing soil by digging it up) to restore the carbon content of degraded soils and reduce soil disturbance.
• avoid burning crop residues.
• practise agro-forestry (growing trees on farming land for timber and other forest products).
• adopt a vegetarian diet or at least reduce meat consumption.

Source(s):
‘Cool Farming: Climate Impacts of Agriculture and Mitigation Potential’, Greenpeace International, by Jessica Bellarby, Bente Foereid, Astley Hastings and Pete Smith, 2007 Full document.

Funded by: Greenpeace UK

id21 Research Highlight: 5 April 2008

Further Information:
Pete Smith
School of Biological Sciences
University of Aberdeen
Cruickshank Building
St Machar Drive
Aberdeen AB24 3UU
UK

Tel: +44 1224 272702
Fax: +44 1224 272703
Contact the contributor: pete.smith@abdn.ac.uk

School of Biological Sciences, University of Aberdeen, UK

Greenpeace International
Ottho Heldringstraat 5
1066 AZ Amsterdam
The Netherlands

Tel: +31 20 7182000
Fax: +31 20 5148151
Contact the contributor: supporter.services@int.greenpeace.org

Greenpeace International, The Netherlands

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'Developments in adaptation: new responses to climate change'

'Does low external input agriculture reach the poor?'