Two of today’s major problems are the need to increase food production to achieve food security, and the need to mitigate climate change. However, their potential solutions produce a conflict. DeFries and Rosenzweig (2010) look at the trade-offs that the solutions entail in tropical regions, and note that tropical countries highly value both the agriculture<!–[if supportFields]>XE “agriculture” <![endif]–><!–[if supportFields]><![endif]–> and forest<!–[if supportFields]> XE “forest” <![endif]–><!–[if supportFields]><![endif]–> sectors, but the extensive land use in these areas tends to exacerbate climate change. On the other hand, global food production is only slightly increased by deforestation<!–[if supportFields]> XE “deforestation” <![endif]–><!–[if supportFields]><![endif]–>-related agricultural development. Redirection of agricultural expansion to already cleared lands, improvement of soil quality and livestock management, and other policy intervention may allow increased agricultural production without exacerbating climate change. The authors find that there is no easy balance for achieving these objectives in the tropics, but place-specific strategies based on regionally varying factors are a start. —Whitney Dawson
DeFries, R., Rosenzweig, C., 2010. Toward a whole-landscape approach for sustainable land use in the tropics. PNAS published ahead of print November 16, 2010, doi:10.1073/pnas.1011163107
DeFries and Rosenzweig use past studies to examine the linkages between climate change mitigation and food security. They find that the greatest possibility to mitigate climate change is through change in agricultural land use. The only remaining biomes where enough land is available for expansion of agricultural production are in tropical forests and woodlands. However, agricultural expansion is the primary cause of deforestation<!–[if supportFields]> XE “deforestation” <![endif]–><!–[if supportFields]><![endif]–>. Estimates from various data sources strongly conclude that deforestation results in a very small increase of agricultural area, but causes a huge increase in carbon dioxide emissions. The majority of greenhouse gas emissions in tropical countries are due to the use of land for agricultural practices, different from most other countries whose mitigation possibilities are in the energy sector. The predominant agricultural activity that emits GHGs is controlled fires for clearing biomass for deforestation. Tropical regions are increasing GHG emissions at the most rapid rate.
Agricultural intensification, or increasing output per area, is identified as a primary focus for increasing food production in a more sustainable manner. Intensification would allow less deforestation<!–[if supportFields]> XE “deforestation” <![endif]–><!–[if supportFields]><![endif]–> to occur due to a more efficient use of land, and would therefore result in less GHG emissions. A possible exception the authors point out is that higher livestock densities and chemical inputs might result from intensification, which would both add to the level of emissions. Based on multiple analyses, the authors concluded that reducing deforestation will not necessarily lead to increased food production.
DeFries and Rosenzweig suggest the need to view landscapes from a cross-sector perspective to recognize opportunities that minimize trade-offs between food production and climate change mitigation. The authors emphasize the need to examine agricultural practices at a local level, since specific areas have a wide array of variables that also affect crop yields. Strategies to achieve the objectives require analyses of options that consider site-specific characteristics. Trade-offs between food production and climate change mitigation vary between small and large-scale agricultural systems.
The foremost opportunity for tropical countries to mitigate climate change arises in the forest<!–[if supportFields]> XE “forest” <![endif]–><!–[if supportFields]><![endif]–> and agricultural sectors. Emissions of GHGs are increasing at a more rapid rate in tropical Asia and Latin America than in the rest of the world. Compared to temperate regions, almost twice as much carbon is lost from a unit of cleared land in the tropics, producing less than half of the crop yield. The opportunities for mitigating climate change and increasing agricultural production will not spontaneously occur, but will require the help of policies. Policy options discussed have been heavily focused on the mitigation potential of REDD (Reducing Emissions from Deforestation and forest Degradation), although this option does not consider food security. A careful balance must be made when considering policies that deal with deforestation<!–[if supportFields]> XE “deforestation” <![endif]–><!–[if supportFields]><![endif]–> because food production could be negatively affected. DeFries and Rosenzweig note that policies should aim at locating new production opportunities on land that has already been cleared, rather than clearing new land. They suggest a policy focus on guidelines for international trade that encourage agricultural commodities produced on already cleared land.