Richard Robertson

Food security, farming, and climate change to 2050: Scenarios, results, policy options

As the global population grows and incomes in poor countries rise, so too, will the demand for food, placing additional pressure on sustainable food production. Climate change adds a further challenge, as changes in temperature and precipitation threaten agricultural productivity and the capacity to feed the worlds population. This study assesses how serious the danger to food security might be and suggests some steps policymakers can take to remedy the situation.

Climate change effects on agriculture: Economic responses to biophysical shocks

Significance Plausible estimates of climate change impacts on agriculture require integrated use of climate, crop, and economic models. We investigate the contribution of economic models to uncertainty in this impact chain. In the nine economic models included, the direction of management intensity, area, consumption, and international trade responses to harmonized crop yield shocks from climate change are similar. However, the magnitudes differ significantly. The differences depend on model structure, in particular the specification of endogenous yield effects, land use change, and propensity to trade. These results highlight where future research on modeling climate change impacts on agriculture should focus. Agricultural production is sensitive to weather and thus directly affected by climate change. Plausible estimates of these climate change impacts require combined use of climate, crop, and economic models. Results from previous studies vary substantially due to differences in models, scenarios, and data. This paper is part of a collective effort to systematically integrate these three types of models. We focus on the economic component of the assessment, investigating how nine global economic models of agriculture represent endogenous responses to seven standardized climate change scenarios produced by two climate and five crop models. These responses include adjustments in yields, area, consumption, and international trade. We apply biophysical shocks derived from the Intergovernmental Panel on Climate Change’s representative concentration pathway with end-of-century radiative forcing of 8.5 W/m2. The mean biophysical yield effect with no incremental CO2 fertilization is a 17% reduction globally by 2050 relative to a scenario with unchanging climate. Endogenous economic responses reduce yield loss to 11%, increase area of major crops by 11%, and reduce consumption by 3%. Agricultural production, cropland area, trade, and prices show the greatest degree of variability in response to climate change, and consumption the lowest. The sources of these differences include model structure and specification; in particular, model assumptions about ease of land use conversion, intensification, and trade. This study identifies where models disagree on the relative responses to climate shocks and highlights research activities needed to improve the representation of agricultural adaptation responses to climate change.

Climate change impacts on agriculture in 2050 under a range of plausible socioeconomic and emissions scenarios

Previous studies have combined climate, crop and economic models to examine the impact of climate change on agricultural production and food security, but results have varied widely due to differences in models, scenarios and input data. Recent work has examined (and narrowed) these differences through systematic model intercomparison using a high-emissions pathway to highlight the differences. This paper extends that analysis to explore a range of plausible socioeconomic scenarios and emission pathways. Results from multiple climate and economic models are combined to examine the global and regional impacts of climate change on agricultural yields, area, production, consumption, prices and trade for coarse grains, rice, wheat, oilseeds and sugar crops to 2050. We find that climate impacts on global average yields, area, production and consumption are similar across shared socioeconomic pathways (SSP 1, 2 and 3, as we implement them based on population, income and productivity drivers), except when changes in trade policies are included. Impacts on trade and prices are higher for SSP 3 than SSP 2, and higher for SSP 2 than for SSP 1. Climate impacts for all variables are similar across low to moderate emissions pathways (RCP 4.5 and RCP 6.0), but increase for a higher emissions pathway (RCP 8.5). It is important to note that these global averages may hide regional variations. Projected reductions in agricultural yields due to climate change by 2050 are larger for some crops than those estimated for the past half century, but smaller than projected increases to 2050 due to rising demand and intrinsic productivity growth. Results illustrate the sensitivity of climate change impacts to differences in socioeconomic and emissions pathways. Yield impacts increase at high emissions levels and vary with changes in population, income and technology, but are reduced in all cases by endogenous changes in prices and other variables.

Maize systems under climate change in sub-Saharan Africa

Purpose – The purpose of this study is to examine the biophysical and socioeconomic impacts of climate change on maize production and food security in sub-Saharan Africa (SSA) using adapted improved maize varieties and well-calibrated and validated bioeconomic models. Design/methodology/approach – Using the past climate (1950-2000) as a baseline, the study estimated the biophysical impacts of climate change in 2050 (2040-2069) and 2080 (2070-2099) under the A1B emission scenario and three nitrogen levels, and the socioeconomic impacts in 2050. Findings – Climate change will affect maize yields across SSA in 2050 and 2080, and the extent of the impact at a given period will vary considerably between input levels, regions and maize mega environments (MMEs). Greater relative yield reductions may occur under medium and high-input intensification than under low intensification, in Western and Southern Africa than in Eastern and Central Africa and in lowland and dry mid-altitude than in highland and wet mid-alt...

Climate change and agriculture in South Asia : alternative trade policy options

There is increasing evidence suggesting that climate change will negatively impact agricultural production in South Asia. Decreased domestic production may make South Asian countries more dependent on imports. The extent to which South Asia will need to increase its imports as a result of climate change will presumably depend on the degree to which the latter will affect domestic output. The effects of climate change on agriculture may well differ substantially for individual South Asian countries and indeed for regions within a given country which can be approximated by food production units. This calls for an analysis of climate change effects on trade flows under alternative trade policy regimes both for agriculture and non-agricultural sectors. The specific objectives of the paper include the following: analyze the extent to which agricultural production in South Asia and elsewhere in the world may be affected by different scenarios regarding climate change; analyze the extent to which changes in domestic production in South Asia resulting from climate change will lead to increased demand for imports by South Asian countries; analyze the effects of increased import demand in South Asia and changing exportable surpluses elsewhere on world market prices of major agricultural commodities consumed in South Asia; to the extent that South Asian governments allow transmission of changes in world market prices to domestic prices, analyze the potential welfare effects of changes in the latter; analyze if, and to what extent, worldwide trade liberalization and implementation of South Asian Free Trade Area (SAFTA) will dampen the effects of climate change on domestic agricultural prices in South Asia. In this context, the report is organized as follows: chapter one gives introduction. Chapter two describes the methodology used - with particular attention to how different models and modeling techniques are linked to produce an as accurate as possible assessment based on state-of-the-art knowledge. Chapter three provides an up-to-date analysis of trade flows and policies, and production patterns for key food products in South Asia to explain the context in which climate change is taking place. Chapter four describes the climate change scenarios and illustrates their consequences for crop yields at a global level and for South Asia - and in particular shows the vulnerability of the region to these changes. Baseline design, simulations, and results are discussed in chapter five. The final chapter six provides a short summary, discusses the limitations of the analysis, and derives suggestions and guidelines for future research.

Who Bears the Costs of Climate Change? Evidence from Tunisia

In order to estimate the economic costs of climate change for Tunisia, this paper uses a combination of biophysical and economic models. In addition, the paper draws on the literature to complement the quantitative analysis with policy recommendations on how to adapt to the changing climate. The results bear out the expectation that climate change has a negative but weak overall effect on the Tunisian economy. Decomposing the global and local effects shows that global climate change may benefit the agricultural sector since higher world market prices for agricultural commodities are likely to stimulate export expansion and import substitution. Locally felt climate change, however, is likely to hurt the agricultural sector as lower yields reduce factor productivities and lead to lower incomes and higher food prices. The combined local and global effects are projected to be mostly negative and the costs will have to be carried mainly by urban and richer households. From a policy perspective, the results suggest that Tunisia should try to maximize the benefits from rising global agricultural prices and to minimize (or reverse) declining crop yields at home.