Moderating the impact of climate change

Summary of published research¹

Adaptations to guard against the impact on food security of climate change are reviewed in a recently published article. The authors start with the assertion that relatively inexpensive changes, such as shifting planting dates or switching to another existing crop variety, may moderate negative impacts. However, the biggest benefits will probably result from more costly measures, including the development of new crop varieties and expansion of irrigation. Such measures will require substantial investments by farmers, governments, scientists and development organisations. Prioritisation of investment needs, such as through the identification of 'climate risk hot spots', is therefore a critical issue.

The authors consider three components to be essential to any prioritisation approach: selection of a time scale over which impacts are most relevant to investment decisions, a clear definition of criteria used for prioritisation, and an ability to evaluate these criteria across a suite of crops and regions. The authors focus on food security impacts by 2030, a time period most relevant to large agricultural investments, which typically take 15-30 years to realise full returns.

Twelve major food insecure regions are identified. Each of these comprises groups of countries with broadly similar diets and agricultural systems and that contain a notable share of the world's malnourished individuals, as estimated by the Food and Agricultural Organisation (FAO). Statistical models for evaluating climate change impacts across a suite of crops and regions were then developed using data on historical crop harvests, monthly temperatures and precipitation and maps of crop locations.

Based on the various projections, the authors identified a small subset of crops that met different prioritisation criteria. Because attitude to risk differs and the impact projections for some crops are more uncertain than for others, various institutions might derive different priorities. For example, one set of institutions might wish to focus on cases where negative impacts are most likely to occur, to maximise investment benefits. By this criterion, South Asia wheat, Southeast Asia rice, and Southern Africa maize appear as the most important crops in need of adaptation investments. Other institutions may want investments to target crops and regions for which some models predict very negative outcomes. This would mean a different subset of crops with several South Asian crops, Sahel sorghum and South African maize (again) appearing as the most in need of attention.

Either of these risk attitudes can be applied with an explicit regional focus. For a sub-saharan African institution interested in investing where negative impacts are most likely to occur (where median impact projections are substantially negative, or where most climate models agree that negative impacts are likely to occur), priority investments would include Southern Africa maize, wheat and sugarcane, Western Africa yams and ground nut, and Sahel wheat.

Despite the many assumptions and uncertainties associated with the crop and climate models used, the analysis points to many cases where food security is clearly threatened by climate change in the relatively near-term. The importance of adaptation in South Asia and Southern Africa appears particularly robust. The results also highlight several regions (e.g. Central Africa) where climate-yield relationships are poorly captured by current data sets, and therefore future work is needed to inform adaptation efforts.

The authors conclude that impacts will probably vary substantially within individual regions according to differences in biophysical resources, management and other factors. Therefore, the broad-scale analysis that they present only identifies major areas of concern and that further studies at finer spatial scales are needed to resolve local hot spots within regions.

¹Lobell. D (2008). Prioritising climate change adaptation needs for food security in 2030. SCIENCE, vol 319, 1st February 2008, pp 607-610 Available at http://www.sciencemag.org