Climate change and agriculture
Agriculture not only contributes to climate change and is affected by it, it also forms part of the solution. Coherent and effective policies are needed.
At least 14% of global greenhouse gas emissions come directly from the farm sector. That is more than transport and not far behind the contribution from industry.
How does agriculture produce such high emissions? One way is through farming activity itself: ploughing fields releases carbon dioxide in the soil, and rice cultivation and livestock breeding both emit large quantities of methane. Farming uses fossil fuels and fertilizers. Agriculture also involves land-use changes, including deforestation and desertification of fragile grasslands. These changes alter the earth’s ability to absorb or reflect heat and light.
Despite its relatively high contribution to greenhouse gas emissions, agriculture is not yet subject to emissions caps under the Kyoto agreement to fight climate change. Nevertheless, governments are taking action, and the OECD is supporting their efforts through analysis, information sharing and policy advice.
Devising policies and undertaking commitments to mitigate climate change through agriculture clearly means knowing more about agriculture’s carbon footprint. As in most other sectors this carbon footprint is increasing, since farming is set to expand to produce more food for a growing world population. In fact, food production will need to double from current levels if projections of more than 9 billion people in 2050 prove correct. That means more land-use change, more cultivation, more livestock and more use of fossil fuels.
But there are other, different challenges to contend with too. As well as being a source of climate change, agriculture is affected by shifts in climate. Projections to 2050 suggest an increase in both global mean temperatures and weather variability, including precipitation. This will clearly affect the type and location of agricultural production worldwide–from the vines of Europe through pasture in Africa to rice in Asia, whole patterns of production and livelihoods could be transformed.
Many countries will be able to adapt and some may even benefit by being able to grow new crops. But poorer communities and those living in fragile lands, such as deltas and low-lying coasts, may be exposed to greater risks. This makes adaptation vitally important. It also confirms just how key global co-operation will be in meeting adaptation needs in the years ahead.
While agriculture contributes to climate change, it is also one of the few sectors that can provide solutions. Greenhouse gas emissions from human activity will have to decrease globally from 1990 levels by at least 50% by 2050 if future global warming is to be limited to a 2°C temperature increase, as currently recommended by the Intergovernmental Panel on Climate Change. This imperative was repeated by world leaders at the UN Climate Change conference in Copenhagen in December 2009.
How can farming help? One answer is carbon sequestration, as soil literally captures and absorbs carbon and so offsets emissions not only from farming, but from other sectors too.
As for mitigation, policies aimed at reducing emissions in agriculture may be more cost-competitive than in some industrial and transport options.
There are challenges though, including in measurement. Quantifying greenhouse gas emissions from agricultural activities is complex and costly, given the variety of farmers and systems used over a wide range of geographic and climatic conditions. Moreover, there remains a great deal of scientific uncertainty about how to control emissions from agriculture, since many factors are at play, such as local climate, soil type, slope and production practices. In other words, there is no simple relationship between the quantity of production and emissions.
Calculating indirect land-use changes arising from agricultural production is another challenge. The global surge in food prices in recent years reflected competition for land use related to world food and energy markets. In particular, the links between production of biofuels from feedstock–these are subsidised in many countries–consequent land-use changes, including deforestation, and effects on food prices need to be further explored.
Mitigate and adapt
With the right technologies and systems, improved cropland and grazing land management, restoration of degraded lands and land-use change, such as agro-forestry, can make a major contribution to limiting greenhouse gases. Emissions from livestock production can be reduced by improving nutrition and manure management.
Science offers promising solutions in areas such as genetics, so-called secondgeneration biofuels that compete less with land used for food crops, and carbon capture, though clearly more research is needed. Genetics, for instance, could help reduce methane from animals too. Cattle and sheep’s sizeable share of greenhouse gases–indeed, methane is many times more potent than carbon dioxide as a greenhouse gas–can be offset to some extent by capturing the carbon in pastureland. Better farming methods can help mitigate climate change while also improving water quality, biodiversity and soil quality.
Though some regions of the world may benefit from improved climatic conditions, if no action is taken, the overall effect for global agricultural production is expected to be negative. Adaptation will be important, given that we are already “locked-in” for a certain amount of climate change, and since mitigation efforts take time to have an effect. This could mean altering farmmanagement practices to adopting new varieties, crops and animal breeds more appropriate to future climate conditions. It may mean policies to discourage certain kinds of heavily emitting agriculture to reduce risks and slow down land-use changes. In any case, such policies will also relieve other environmental stresses, including in water supply, and make agriculture more sustainable (see article on water).
The stakes are high, and there are serious issues to address. Responding to climate change and other environmental concerns, while at the same time producing enough food to meet demand, will not be easy. The OECD is looking hard at the questions, such as the synergies and trade-offs as producers reduce their carbon footprint while remaining competitive. How can carbon markets make a difference and how can they be made more effective? And what efficiencies can be achieved in the processing, transport and distribution of food products throughout the supply chain?
Getting policies right in these areas will be key, as will working with markets to encourage trade and investment, and to correct distortions caused, for instance, by certain subsidies that lead to overproduction and resource depletion. In short, future policies must aim for better environmental outcomes, including lower emissions. The OECD is analysing the design and implementation of cost-effective adaptation and mitigation policies in a range of key areas. Carbon markets, crop and disaster insurance, adoption of better crop varieties and breeds, technology, emissions monitoring, incentives for more efficient water use and compensation for vulnerable groups: such measures, if taken together and adapted to specific country situations, would create coherent policy packages to limit agriculture’s contribution to climate change, improve the environment and boost the effectiveness and value-added of the farming sector.
OECD (forthcoming 2010), Climate Change and Agriculture: Impacts, Adaptation and Mitigation, Paris.
OECD (2008), Environmental Performance of Agriculture in OECD Countries Since 1990, Paris.
©OECD Observer n°278, March 2010
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