Global warming

Responding to the threat

The world’s farmers face many challenges: meeting the ever-increasing demand for food, overcoming land degradation, reducing rural poverty and, to an ever larger extent, coping with the impact of climate change. At the same time, agriculture should contribute to mitigating climate change.

[ By Gerald Nelson ]

While the long-term outcomes are uncertain in important details, there is little doubt that climate change presents an extremely serious threat to food security. As policymakers contend with a broad range of climate-change related issues during the negotiations for the United Nations Framework Convention on Climate Change, helping farmers adapt must be a priority. Last year’s food price crisis was a timely reminder that food security cannot be taken for granted.

At the same time, policymakers must recognise that improved farming practices can help to mitigate greenhouse gas (GHG) emissions, both those from agriculture and other parts of the economy. Agriculture currently accounts for about 29 % of global GHG emissions directly, as well as indirectly through land-use change.

The good news is that agricultural productivity improvements provide one of the most cost-effective ways to reduce GHG emissions. The bad news is that it will take time to develop the tools needed for adaptation and mitigation. Farmers will need drought- and stress-tolerant crops. Improved inputs must be developed and made available. New technologies and infrastructure will be required. Revitalised extension services will be critical for passing along improved farming practices. These needs must be addressed now to ensure that the necessary resources are available to respond to global warming.

Gaps in research and information

Responding effectively to climate change requires a much clearer picture of how and where it will affect farming. Today, there is considerable uncertainty about where the effects will occur and how serious they will be. Farming is an extremely location-specific vocation. Higher temperatures and more extreme weather events will occur across the globe, but farmers want to know how exactly their farms and livelihoods will be affected, and national policymakers want to know how climate change will affect the various regions in their countries.

Existing data are still too sparse and uncertain to provide either farmers or policymakers with reliable information for decision-making. Regular repeated observations from space, combined with ground-based observations, could provide low-cost information on land-use change and its drivers. More information is needed on local changes in temperature, weather and migratory patterns, and new insects and diseases, as well as the effects of these changes on specific plant and livestock varieties.

Fortunately, promising activities are beginning. For example, the African Soil Information Service has begun digitally mapping and monitoring key soil properties across sub-Saharan Africa, using quick, inexpensive spectroscopy. Similar technologies should be developed and purchased to support data collection across the range of data needs in developing countries. Until these knowledge gaps are eliminated, decision-makers cannot anticipate effects and plan for the future.

Data gathering is an important first step, but open information dissemination is also essential. Farmers have first-hand information of local environments, while researchers and scientists have more extensive global data and advanced technology. Both groups should work together to share their complementary knowledge.

Knowledge sharing

Much research is already underway that can help agriculture be more resilient to climate change, although coordination needs to be improved. But gaps in the coverage of today’s climate and agro-ecosystems exist. One solution is to develop a set of agricultural research and test fields, including both existing locations run by national and international organisations as well as new ones that cover all of the earth’s current agroclimatic zones to test existing germplasm under widely varying conditions, and to explore the potential for new management systems for tomorrow’s climate.

New systems of acquiring data and sharing knowledge must also be developed. A crop variety or management system that performs well in one location today might be critical to farmers halfway around the world after 20 years of climate change. The international community should develop data banks for agriculture and climate-change information to complement gene banks, and should reach agreements about open sharing of information and technology.

Research and knowledge sharing, no doubt, will enable many farmers to cope with climate change (see box). It is not enough to help farmers adapt to the phenomenon, however. Since agriculture is such a major contributor to GHG emissions, policymakers must also pursue mitigation strategies.

Potential mitigation practices include draining flooded rice fields at least once a season to decrease methane emissions. Livestock producers can maintain fewer, better-fed animals, and possibly change the species and breeds they raise. Agricultural nitrous oxide emissions can be reduced through more judicious application of nitrogen-based fertiliser, development of alternative fertiliser additives, and use of natural fertilisers such as manure and crop residues. Nitrogen-fixing crops such as legumes can also mitigate nitrogen run-off and emissions.

In addition to limiting its own emissions, agriculture can remove atmospheric carbon emitted from other parts of the economy through sequestration, both above and below ground. The Intergovernmental Panel on Climate Change found that 90 % of the world’s technical potential for climate-change mitigation is in sequestration in developing countries. Soil sequestration potential from agriculture is as much as 3 billion metric tons of carbon per year, which would offset more than a quarter of all fossil fuel emissions worldwide.

Soil carbon can be increased through conservation agriculture and integrated nutrient management. Other sequestration techniques include replacing annual crops with perennials, favouring plants with deep root systems, and managing pasture with grazing rotations or controlled fire. All of these practices increase soil fertility and productivity. Restoration of degraded soils, those with the most potential for increased carbon sequestration, also increases the productivity of that land. Further benefits include greater efficiency of inputs and reduced soil erosion, sedimentation, and pollution.

Forestry techniques can also contribute to soil sequestration. While preventing deforestation is a well-known, proven strategy, incorporating agroforestry into crop rotations can also be effective.

It is important to assess the complete set of climate-change effects of planned mitigation activities. Some strategies may decrease certain GHG emissions while contributing to global warming in other ways. For example, policies that discourage deforestation might increase emissions from farming. Changing the composition of livestock might minimise methane production but increase carbon dioxide emissions through increased feed production. An integrated approach to the net effects of methane, nitrogen, and carbon emissions is necessary to assess the value of these options.

Mitigation policies

In spite of the potential benefits, agricultural sequestration measures have not been generally favoured, both because decision makers have insufficient information about the possibilities and because implementation costs are seen as too high. Further research into ways to reduce costs is necessary, both in terms of sequestration itself but also for monitoring and verification.

Improved access to carbon markets is critical for accelerating the adoption of mitigation strategies that require changes by low-income farmers. Drawing on the considerable experience with payments for land preservation and watershed management in the developed world, developing country policymakers might use similar incentives to encourage adopting soil sequestration and crop and livestock systems that reduce methane emissions.

Such incentives would have the additional benefit of diversifying farmers’ incomes and improving resilience through increased resources and participation in broader networks. To support participation in carbon markets, policymakers should develop simple mechanisms for aggregating smallholder efforts into marketable units that would reduce administrative costs and improve monitoring, verifying, and payment distribution.

It is important to recognise that adaptation and mitigation are almost always mutually reinforcing strategies. Mitigation technologies can strengthen the resilience of farmers to climate change. Through effective planning and implementation, we can reap large synergies between adaptation, mitigation, agricultural productivity and poverty alleviation.

Fortunately, agriculture is no longer the missing word from the United Nations negotiations on climate change. After initial neglect, agriculture has made its way onto the agenda. Regardless of the ultimate outcome of the current round of talks, negotiators should commit now to providing funds for adaptation and mitigation for agriculture. Given the lead times needed for research and programme development, there is no better time to start than now.

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