Climate Change Could Devastate Latin America's Agriculture

The melting of the Andean glaciers. Massive die-off of the Amazonian rainforests. Rising sea-levels and the inundation of low-lying regions on Colombia's Caribbean coast. By now, this panorama is familiar to anyone who looks at the potential impacts of anthropogenic global warming on Latin America.

Less familiar, though equally serious, is the damage climate change could wreak on the region's agriculture.

The world's total agricultural production could decrease between 3 percent and 15 percent due to global climate change, according to the World Bank. Studies suggest those numbers could be much worse in the agricultural regions of Latin America's equatorial belt. 

How severe the impact on agriculture gets will depend in part on the existence and the magnitude of the carbon fertilization effect. Carbon fertilization is an increase in crop growth due to greater atmospheric carbon interacting with sunlight through photosynthesis.

Analysts concede that a carbon fertilization effect likely won't reach the levels many hoped for. As economist William Cline, who analyzes the effects of climate change on world agriculture, comments:

"I think it would be extremely risky to assume that carbon fertilization is the solution to this problem."

Keep in mind that Cline's study and the World Bank analysis, which was partly based upon it, may still sharply underestimate agricultural losses.

Neither deals with increased damage from pests or more severe weather conditions. Furthermore, Cline's study used information from the 2001 IPCC baselines projections. But by now, the 2007 IPCC  projections are considered overly conservative and very likely underplay the warming that will occur if greenhouse gas emissions continue on their current trajectory. As Cline writes:

"For several reasons, then, declines in global agricultural capacity by the 2080s could thus easily be greater than the estimates in this study and perhaps lie in the range of 10 to 25 percent."

According to a just-released World Bank study, revenue losses in Latin America's agricultural sector could range from 12 percent to 50 percent by 2100, even after accounting for a certain level of technological adaptation to climate change.

Cline's study suggests that total agricultural production in Latin America could, by the 2080s, fall by 12 percent if carbon fertilization takes place and as much as 24 percent if it does not. The models cannot account for the effects of hurricanes or droughts, which most climate models suggest are likely to occur far more frequently as the climate heats up.

Every country in the region will see its agricultural production fall without carbon fertilization, anywhere from 5 percent to over 25 percent, the study shows. And even if the fertilization effect occurs, only Argentina will see a net increase in production levels.

This reduction will contribute to a massive global food crisis if steps aren't taken to arrest it, because the food exporting countries of the region have food trade balances as high as 12 percent of GDP, as is found in Guyana. That means they feed the world, even though some of those countries also have high food insecurity, meaning their own people can't afford basic nutrition. In Brazil, an estimated 46 million people are considered food-insecure, according to the USDA.

The shrinking of Latin America's agricultural systems will then contribute to a shrinking of global food production.

The situation looks even more dire when one narrows the focus to individual countries.

"Climate change can have extremely severe consequences for Colombian agriculture," commented Walter Vergara, a bank climate change expert who spoke during the presentation of the study in Bogota last month. In the worst-case scenario, Colombian farm production would nearly vanish due to temperature rises between 2.5 to 5 degrees Celsius and a 10 percent variation in annual rainfalls.

In nearly all the situations modeled, Brazil, Peru, and Ecuador were hit hard, due in large part to their proximity to the Equator. Equatorial countries are particularly vulnerable to climate change because crops grown there are already close to the limits of their ability to tolerate extreme temperatures.

Colombia, too, is quite close to the equator, and as an Andean country, relies on glacial irrigation for its crops, much like Ecuador and Peru. The three have contributed a tiny fraction of the world's greenhouse gases compared to industrialized nations, yet they stand to suffer significant loses.

Venezuela would also be severely affected, with its land losing 75 percent of its value and its production plummeting by 38 percent by the 2080s, but despite recent increases in agricultural production, it imports most of its food and does not rely on subsistence agriculture so much as the other countries in the region.

Finally, Mexico could see losses of between 30 and 35 percent in its agricultural base. And here, let's stop for a moment, because such a loss could have a massive, unforeseen externality.

A great many Mexican farmers grow corn on subsistence plots—milpas—creating a biological vault which world farmers can go back to for needed seed-stock. They might need seeds more resistant to climate change, extreme weather, such as droughts, or blights, such as the one that plagued the American corn crop in 1970, wiping out 15 percent of total production.

Indeed, botanist H. Garrison Wilkes calls the milpa patch an "evolutionary garden," where, as agronomist James Boyce notes, "in response to climate change and newly evolving strains of pests and plant diseases" corn is able to dynamically evolve and respond to external environmental change. Thus the Mexican maize farmers' social mode of production results in a "valuable positive externality to humankind—the in situ conservation and evolution of genetic diversity" in one of the world's most important cereal crops.

The destruction of Mexican agriculture could mean the loss of many such seed varieties, one more negative effect of climate change unforeseen and unforeseeable in IPCC model.

Such losses can be mitigated. But only so much, and only for so long.

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