effect of climate change on global potato production, The

American Journal of Potato Research, Jul/Aug 2003 by Hijmans, Robert J

Accepted for publication 17 April 2003.

ABSTRACT

The effect of climate change on global potato production was assessed. Potential yields were calculated with a simulation model and a grid with monthly climate data for current (1961-1990) and projected (2010-2039 and 2040-2069) conditions. The results were mapped and summarized for countries. Between 1961-1990 and 2040-2069 the global (terrestrial excluding Antarctica) average temperature is predicted to increase between 2.1 and 3.2 C, depending on the climate scenario. The temperature increase is smaller when changes are weighted by the potato area and particularly when adaptation of planting time and cultivars is considered (a predicted temperature increase between 1 and 1.4 C). For this period, global potential potato yield decreases by 18% to 32% (without adaptation) and by 9% to 18% (with adaptation). At high latitudes, global warming will likely lead to changes in the time of planting, the use of later-maturing cultivars, and a shift of the location of potato production. In many of these regions, changes in potato yield are likely to be relatively small, and sometimes positive. Shifting planting time or location is less feasible at lower latitudes, and in these regions global warming could have a strong negative effect on potato production. It is shown that heat-tolerant potato cultivars could be used to mitigate effects of global warming in (sub)tropical regions.

RESUMEN

Se estudio el efecto del cambio climatico en la produccion global de la patata. Los rendimientos potenciales fueron calculados con un modelo de simulacion y una rejilla con datos mensuales de clima para las condiciones actuales (1961-1990) y proyectadas (2010-2039 y 2040-2069). Los resultados fueron presentados en mapas y resumidos por paises. Se predice que entre 1961-1990 y 2040-2069 la temperatura media global (en areas terrestres excepte la Antartica) aumentara entre 2.1 y 3.2 C, dependiendo del escenario climatico. El aumento de la temperatura es mas pequeno cuando los cambios son ponderados con el area del cultivo de la patata y particularmente cuando se considera la adaptacion de la epoca de siembra y de los cultivares (se predice un aumento de la temperatura entre 1 y 1.4 C). En este periodo, la produccion potencial global de la patata disminuye de 18% al 32% (sin adaptacion) y de 9% al 18% (con adaptacion). En latitudes mayores, el calentamiento global podria conducir a cambios en la epoca de siembra, el uso de cultivares mas tardios, y cambio de los lugares donde se produce patata. En muchas de estas regiones, los cambios en la produccion de la patata serian relativamente pequenos, y a veces positivo. Los cambios en la epoca de siembra o de los lugares de produccion son menos factibles en latitudes mas bajas, en estas regiones el calentamiento global podria tener un fuerte efecto negativo en la produccion de la patata. Se muestra que se podrian utilizar cultivares con tolerancia al calor para atenuar el efecto del calentamiento global en regiones (sub)tropicales.

ADDITIONAL KEY WORDS: Adaptation, heat tolerance, geographic information systems, GIS, potential yield, simulation, Solanum tuberosum.

INTRODUCTION

It is likely that the currently observed trend of global warming, which has been 0.6 C or - 0.2 since 1900, will continue and that the average global temperature will increase by between 1.4 and 5.8 C over the period 1990 to 2100 (Houghton et al. 2001). The impact of this type of climate change will probably lead to a decrease in crop productivity, but with important differences between regions (Rosenzweig and Liverman 1992; McCarthy et al. 2001).

The effects of climate change on crop production can be complex. Depending on the temperature regime and the crop, high temperatures can lead to low yields due to increased development rates and higher respiration. However, a short growth cycle can also be beneficial, e.g., to escape drought or frost, and the use of late-maturing cultivars could offset the effect of high development rates. In environments where low temperatures now limit production, global warming could lead to a beneficial lengthening of the growing season and temperatures close to optimal for assimilation. Moreover, global warming is related to the increase of atmospheric CO2 concentration, which is likely to increase crop yields, particularly when water limits crop production (Nonhebel 1993).

Potato is grown in many different environments, but it is best adapted to temperate climates (Haverkort 1990). At high temperatures (above 17 C; Stol et al. 1991) tuberization diminishes (Reynolds and Ewing 1989a). Potato is also frost sensitive, and severe damage may occur when temperature drops below 0 C (Hymans et al. 2003). Various authors have used simulation models to study the effect of global warming on potato production. Higher temperatures are predicted to increase potato yields in England and Wales (Davies et al. 1996), Scotland (Peiris et al. 1996) and Finland (Carter et al. 1996), primarily because of a longer growing season. However, an overall yield decrease was predicted for the USA (Rosenzweig et al. 1996).