Global warming and wheat production in Argentina

MAGRIN G.; TRAVASSO M.I.; RODRIGUEZ, G; SOLMAN S; NÚÑEZ M.

International Journal of Global Warming

Interscience Publishers

Lugar: Ginebra; Año: 2009 vol. 1 p. 201 - 213

1758-2091

Argentina is an important wheat producer and highly contributes to global exportations. The main planted area is located in the Pampas region, where the crop is developed under rainfed conditions. In the last decade, the area devoted to wheat ranged between 4.9 and 7.3 millions of hectares, mean yield attained 1,900-2,600 kg/ha, and country’s production varied between 9.4 and 16 millions of tons (Mt). The internal consumption is near to 6 Mt, and remainder production is exported, transforming the country in the fifth world’s exporter with a key role in food security. Changes observed in precipitation and temperature’s increases during the last three decades had changed crops productivity in the Pampas. This is a crucial issue not only for the significant role of commodities in the Argentina’s economy, but also for its potential impact on world food security. The aim of this work was to assess the impact of past and future changes in climate on potential wheat productivity. The study was based on long term daily climatic data (since 1930) and crop productivity, regional climatic scenarios based on the down scaling of HadCM3 GCM (MM5/CIMA), and a crop simulation model (DSSAT v4.0). In the central and northern part of the Pampas, potential wheat yield has been decreasing with increasing rates since 1930 (28.3 kg/ha between 1930-2000, and 52.7 kg/ha between 1970-2000) due mainly to winter and spring warming. Further increases in temperature could lead to wheat yield reductions of 7.5% for each °C of temperature raise until 3°C. According to MM5/CIMA climatic projections, in 2080 under the SRES A2 scenario, temperature will rise between 2°C and 3°C and spring- summer precipitations will have slight increases. Under these conditions mean wheat yield will be reduced by 4% with a great spatial variability. The zones more affected will be those located in the north (Nor-west of Buenos Aires province, and parts of Santa Fe and Cordoba with decreases between 20% and 30%), while the south-west portion could be benefited with increases near to 20% . If CO2 effects are considered mean wheat yield could increase by 14% in the Pampas. However in isolated sites, located mainly in the central and northern part, yields could decrease up to 10% despite CO2 effects.  In the future should be convenient to advance planting dates for taking advantage of the new environmental conditions where frost free periods would be prolonged.