Page 42 - FAO-IPCC Expert meeting on climate change

Adaptation and resilience in food and land-based ecosystems
Unlike mitigation, which has the advantage of a clearly defined metric (GHG emissions), adaptation to climate change is a more difficult concept to tackle, with many possible entry points, different scales and diverse options and outcomes. In this section, adaptation is discussed along specific themes covered in the EM with a view to drawing direct and indirect implications for food security as a cross-cutting concern. As a general observation, discussing the implications of adaptation for food security requires us to make different distinctions. The first is to separate out the different food security dimensions (availability, access, utilisation and stability). The second is to distinguish between adaptation impacts on aggregate metrics (food production, net trade, aggregate freshwater availability etc.) vs local- based indicators (or measures) affecting food security for individuals, households and communities, especially among the poor and food insecure
4.1 Restoring soil ecosystem systems
Soil provides a wide variety of ecosystem services that have an important role in the supply of food and provision of water and nutrients. They act to retain land surface, prevent erosion and transform and accumulate organic matter. The World’s Soil Resource Report, released in December 2015 by the Intergovernmental Technical Panel on Soils, identifies ten major threats to soil functions and soil-mediated ecosystem services.36 These threats are topped by soil erosion which, alone, will generate a global average loss of approximately 0.3 percent of annual crop yield and a total yield loss potential of 10 per cent up to 2050, a reversible gradual loss of productivity every year, worldwide.
Soil erosion impacts negatively on the quality of water which, in many regions, may be more severe than soil productivity effects. Land at risk of abandonment due to human-induced changes in soil function was documented in a 1991 study by the Global Assessment of Human-induced Soil Degradation based on data from the 1980s. A more current assessment should be undertaken, incorporating the land that is at risk under regional climate change scenarios.
In terms of soil management, no-till farming has been the most widely adopted practice to tackle soil erosion. In 2009, no-till farming covered approximately 111 million ha. Compared with conventional practices, it reduces the loss of soil by 60 percent in temperate climates and by up to 99 percent when combined with contour planting in both humid and sub-humid regions.37 No-till farming also lessens the chance of runoff and is shown to have improved yields by 20 - 30 percent over the last 30 years in arid and semi-arid areas such as Morocco.
There are several reasons for the high uptake of conservation agriculture in North America. One reason behind
the adoption of no-till is largely due to the rapid and massive adoption of genetically modified herbicide-tolerant soybeans (and later corn), starting in the mid-1990s. Another reason was economics and cost savings by using less fossil fuel. In Africa, there may be less push for adopting conservation agriculture, when viewed as a fossil-energy saving practice given the lower degree of mechanization in the continent. In Europe, conservation agriculture and reduced tillage are not actively promoted because of the extensive need for chemicals and herbicides to control weeds, particularly with glyphosate and related products. This comes at a high price and is not particularly encouraged by the European Commission. In Brazil, however, presently with approximately 17 million ha under no-till farming, adoption of conservation agriculture not only reversed massive soil degradation, but reduced production risks and increased flexibility in the timing of the operations. Both conventional and no-till farming need herbicides, but because mulching provides weed suppression no-till farming has great potential to diminish the use of herbicides. Nevertheless, more research is needed to advance conservation agriculture, particularly concerning weed management as the possibilities for organic no-till farming on any scale is a significant challenge.
Two conclusions arise regarding soil management practices to control erosion. The first is that no-till farming reduces the need for water and prevents soil erosion in temperate, tropical and sub-tropical regions. The second conclusion relates to integrated landscape management which, together with sustainable intensification, tackles soil erosion and manages water at the watershed level. Integrated landscape management is complex, multi-purpose and will depend on the active engagement and implementation by the individual landholder or farmer. Overall, no-till does offer benefits for climate adaptation, although its contribution to climate mitigation continues to be debated.38
36 The ten threats are soil erosion, biodiversity loss, soil compaction, soil salinization, waterlogging, soil acidification, soil contamination, soil sealing, nutrient imbalance and soil organic matter loss.
37 Moraes et al. (2016).
Powlson et al. (2014; 2015); Sommer and Bossio (2014).
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FAO-IPCC Expert meeting on climate change, land use and food security