Warming to Spur Potato Famine in the Andes?

Eliza Barclay in Coyllurqui, Peru
for National Geographic News

October 1, 2008

When Tito Guillen Rosales was a young boy, his grandfather was a rich man, growing 50 bags of potatoes a year and sharing his surplus with community members who didn't have enough.

"But now his potatoes are covered with worms and plagues and he barely has enough to feed himself," said Rosales, 27, a farmer himself and the mayor of a Peruvian village at 11,000 feet (3,353 meters) in the Cordillera Blanca range of the Andes mountains.

"We are all becoming desperate to find a solution to the changes in the weather and climate that have brought these new pests," Rosales said.

Here in the Andean highlands scientists attribute warmer temperatures and shifting precipitation patterns to global climate change. These shifts are seriously affecting the health of tuber, or root, crops such as the potato.

Late blight, a fungus responsible for the Irish potato famine in the 1800s, appeared for the first time in Coyllurqui sometime in the last 20 years, surprising and flummoxing farmers such as Rosales and his grandfather.

Rising Temperatures

Temperatures in the Andes have increased at a rate nearly two times the global average between 1939 and 1998, according to a 2006 study published by climate researchers in the journal Science.

The study of 268 mountain recording stations found a temperature increase of 0.19 degrees Fahrenheit (0.11 degrees Celsius) per decade, compared with the global average of 0.11 degrees Fahrenheit (0.06 degrees Celsius) a decade.

In much of the Andes, the El Niño Southern Oscillation—atmospheric weather changes tied to shifting Pacific Ocean currents—has intensified the warming of the lowest level of Earth's atmosphere, which has led to higher temperatures at high altitudes.

Long-term warming trends in the Andes could lead to significant increases in insects and pests that consume tuber crops, said Jeffrey Bury, assistant professor of environmental studies at University of California, Santa Cruz. Bury is studying the influence of climate change and glacier recession on individual households in the Andes.

Building a Better Potato

To help farmers combat these new threats, plant breeders are looking to the gene pool of wild species and native varieties in search of traits that can endure climate-related stresses such as drought.

"The crosses we are developing between wild, drought-tolerant varieties and modern potatoes now are for the future," said Meredith Bonierbale, senior potato breeder at the International Potato Center in Lima.

"We have to work fast because drought may be a serious issue soon."

The center is also developing varieties that mature faster to reduce exposure to an unpredictable climate.

But climate change and habitat fragmentation are also threatening the biodiversity of wild potato species—which range from Argentina to the Rocky Mountains—and their genetic resources.

The species endemic to high altitudes are particularly in danger to changes in temperature and precipitation.

"As genetic resources, the wild relatives are the foundation of agriculture and are continuously used for improvement," said Andy Jarvis, an agricultural geographer with Bioversity International in Cali, Colombia.

"But they're not yet fully confirmed in gene banks, and you never know what you need in the future."

According to Jarvis's research, 16 to 22 percent of all wild potato species are threatened with extinction by 2055 as a result of climate change and habitat destruction.

"Even if we halt habitat loss, in the next 50 years, climate change could undo all of the conservation that we already have," said Jarvis.

The native tuber varieties that Andean farmers like Rosales and his family have developed over millennia are also at risk of extinction.

"Households often have to replace native tuber crops with more widely available and less diverse varieties when their harvests decline or they are devastated by pests, freezes, or extreme weather," said Bury of UC-Santa Cruz.

Rosales says the farmers of Coyllurqui need technical assistance from plant breeders and other experts to avert a hunger crisis.

"We are a small municipality but we are asking everyone for help," he said.

"We are struggling now and we are conscious that down the line, climate change is going to get worse."