17 May 2016
Scientists have reviewed different estimates of the extent to which agricultural emissions must reduce to meet the new climate agreement to limit warming to 2°C in 2100. In a new study published in the journal Global Change Biology, scientists from the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), the International Institute for Applied Systems Analysis (IIASA), and partner institutions estimate that the agricultural sector must reduce non-CO2 emissions by 1 billion metric tons per year in 2030, a 17% reduction compared to the reference level projections of about 5.8 GtCO2eq. Yet in-depth analysis also revealed a major gap between the existing mitigation options for the agriculture sector and the reductions needed: currently available interventions would only deliver between 21-40% of mitigation required.
The study focuses on non-CO2 emissions in agriculture, as soil carbon is highly variable and involves many assumptions related to organic matter inputs, carbon-nitrogen ratios, depth and bulk density, and timing of saturation. In addition, global data on carbon in biomass, such as agroforestry, is comparatively weak.
The authors warn that emission reductions in other sectors such as energy and transport will be insufficient to meet the new climate agreement. They argue that agriculture must also play its part, proposing that the global institutions concerned with agriculture and food security set a sectoral target linked to the 2°C warming limit to guide more ambitious mitigation and track progress toward goals.
“There are major differences in the efficiency of agricultural production with respect to non-CO2 emissions in different regions of the world. That means that international trade can bring a big potential for mitigation, by helping to encourage more production in the most efficient regions. However, without global targets for emissions reductions, decentralized approaches to climate mitigation could lead to inadequate pressure to decrease emissions from highly inefficient system such as those in Europe or North America.” says IIASA researcher Petr Havlik, who contributed results from the Global Biosphere Management Model (GLOBIOM) on structural change in the global agricultural sector as means of reducing greenhouse gas emissions to the study.
“This research is a reality check,” comments Lini Wollenberg, leader of the CCAFS Low Emissions Development research program, who led the study. “Countries want to take action on agriculture, but the options currently on offer won’t make the dent in emissions needed to meet the global targets agreed to in Paris. We need a much bigger menu of technical and policy solutions, with major investment to bring them to scale.”
119 nations included mitigation in agriculture in their Intended Nationally Determined Contributions submitted to the UNFCCC. However, no work has been carried out to determine how these pledges will be accomplished.
Agriculture (not including land use change) contributes an average of 35% of emissions in developing countries and 12% in developed countries today. Yet authors warn that efforts to mitigate emissions levels must be balanced with countries’ need to produce enough food, particularly in poorer nations.
“We need to help farmers play their part in reaching global climate goals while still feeding the world,” comments Professor Pete Smith, at the University of Aberdeen, another co-author “Reducing emissions in agriculture without compromising food security is something we know how to do. A lot can already be done with existing best management practices in agriculture. The tough part is how to reduce emissions by a further two to five times and support large numbers of farmers to change their practices in the next 10 to 20 years.”
To realize the 1 billion metric ton per year mitigation target for non-CO2 emissions in agriculture set out in the paper, 21-40% of mitigation could be achieved with known practices, such as:
However, implementation would require massive investment, information sharing and technical support to enable a global-scale transition.
Livestock are responsible for 12% of anthropogenic greenhouse gas emissions. (cc) Neil Palmer | CIAT
Even this effort will not be enough, according to the study. Much higher impact technologies and policies will be needed. Promising technical innovations on the horizon include recently developed methane inhibitors that reduce dairy cow emissions by 30% without affecting milk yields, breeds of cattle that produce lower methane, and varieties of cereal crops that release less nitrous oxide.
Policies that support more ambitious mitigation include introducing more rigorous carbon pricing, taxes and subsidies; governments and the private sector adopting sustainability standards that include reduced emissions in agriculture; and improving the reach of technical assistance for farmers on locally relevant mitigation options, for example through cell-phone and web-based information portals.
Focusing more attention on sequestering soil carbon, increasing agroforestry, decreasing food loss and waste and shifting dietary patterns could all contribute significantly to reducing emissions from agriculture, according to the authors. However, much less work has been done on mitigation of emissions from these sources, so action is needed now to identify options and their impacts.
“This study is the first ever attempting to match the top-down sectorial mitigation demands with the bottom-up mitigation potentials and the corresponding policies at a global scale. This approach needs to be further developed and generalized in order to reach ambitious climate change stabilization targets without conflicting with other sustainable development goals,” adds Havlik.
Wollenberg E et al (2016). Reducing emissions from agriculture to meet the 2°C target. Global Change Biology http://dx.doi.org/10.1111/gcb.13340
Last edited: 31 January 2017
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