Climate Change 2001: Working Group II: Impacts, Adaptation and Vulnerability

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14.2.2.2. Ranching

Ranching is a major land use in many parts of Latin America. In the three countries that dominate the region's agriculture and ranching sector (Brazil, Argentina, and Mexico), pastures occupy four to eight times more area than agriculture (Baethgen, 1997). In much of Latin America, livestock is almost exclusively raised on rangelands, with no storage of hay or other alternative feeds. Grass production in rangelands depends on rainfall, and limited grass availability during dry periods limits cattle stocking rates over most of the region. In areas that are subject to prolonged droughts, such as northeastern Brazil and many rangeland areas in Mexico, production would be negatively affected by increased variability of precipitation from climate change. In the case of cattle in central Amazonia (várzea), higher peak flood stages would cause losses to cattle kept on platforms (marombas) during the high-water period.

In Argentina, some cattle are fed on alfalfa and other forage crops. A 1°C rise in temperature would increase alfalfa yields by 4-8% on average for most varieties, but yields would be reduced by 16-25% in areas north of 36°S and increased by 50-100% south of this latitude (Magrin et al., 1997b).

Table 14-5: Assessments of climate change impacts on annual crops in Latin America.
Study	Climate Scenario	Scope	Crop	Yield Impact (%)
Downing, 1992	+3ºC -25% precipitation	Norte Chico, Chile	Wheat Maize Potato Grapes	decrease increase increase decrease
Baethgen, 1994	GISS, GFDL, UKMO	Uruguay	Wheat	-30
			Barley	-40 to -30
de Siqueira et al., 1994	GISS, GFDL, UKMO	Brazil	Wheat	-50 to -15
			Maize	-25 to -2
			Soybeans	-10 to +40
Liverman and O' Brien, 1991	GFDL, GISS	Tlaltizapan, Mexico	Maize	-20 -24 -61
Liverman et al., 1994	GISS, GFDL, UKMO	Mexico	Maize	-61 to -6
Sala and Paruelo, 1994	GISS, GFDL, UKMO	Argentina	Maize	-36 to -17
Baethgen and Magrin, 1995	UKMO	Argentina Uruguay (9 sites)	Wheat	-5 to -10
Conde et al., 1997a	CCCM, GFDL	Mexico (7 sites)	Maize	increase-decrease
Magrin et al., 1997a	GISS, UKMO, GFDL, MPI	Argentina (43 sites)	Maize	-16 to +2
			Wheat	-8 to +7
			Sunflower	-8 to +13
			Soybean	-22 to +21
Hofstadter et al., 1997	Incremental	Uruguay	Barley	-10a -8 to +5b
			Maize	-15c -13 to +10b
a For 1ºC increase. b Change of -20 to +20% in precipitation. c For 2ºC increase.