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Global climate change increasing risk of crop yield losses and food insecurity in the tropical Andes

  • Findings published last month in the journal Global Change Biology portend a difficult path to rural agricultural adaptation in the tropical Andes and drastically reduced crop yields at a time of growing populations and food insecurity.
  • Researchers found that, with a temperature increase as small as 1.3 degrees C to 2.6 degrees C, nearly all corn plants died when grown at the same elevations as previous years and generations — either eaten by birds or ridden with pests.
  • When the same crop was grown at a higher elevation in order to stay within its temperature comfort zone, the changing soils had an impact. Plants survived with fewer pests, but the crop yield and corn quality was reduced and thus the market value was diminished.

Climate scientists have long observed the adverse impacts of global warming on forest tree and plant species in tropical regions, which force upslope migrations as these species struggle to repopulate and stay within their narrow temperature comfort zones.

Now, a trio of tropical biologists have shifted their forest research techniques to the rural farming regions of the Peruvian tropical Andes and the warming impact on two dietary staples of Latin America — potatoes and corn. Their findings, published last month in the journal Global Change Biology, are grim, portending a difficult path to rural agricultural adaptation and drastically reduced crop yields at a time of growing populations and food insecurity.

“For these crops, which are representative of other crops grown in the tropics, it’s a damned if you do, damned if you don’t outcome,” said Kenneth Feeley, a tropical biologist at the University of Miami and a study co-author. “If farmers ignore climate change and keep farming the same fields they always have, we find it’s going to be disastrous for these crops.”

The researchers, led by biologist Richard Tito, a native Quechua Indian, found that, with a temperature increase as small as 1.3 degrees C to 2.6 degrees C, nearly all the corn plants died when grown at the same elevations as previous years and generations — either eaten by birds or ridden with pests.

When the same crop was grown at a higher elevation in order to stay within its temperature comfort zone, the changing soils had an impact. Plants survived with fewer pests, but the crop yield and corn quality was reduced and thus the market value was diminished.

View of the study area (Huamburque, southern Peru) showing small scale farming plots on the steep of Andean landscape. Photo by Catherine Bravo.

The climate impact on potato farmers was worse. They are already farming on mountain tops, so migrating higher is not an option. With the same temperature increases, the potato plants survived, but the tuber production was greatly deformed and reduced to the point of virtually no market value.

With both crops, only local fertilizers like manure were used, and no pesticides; rural farmers don’t have the funds for the agricultural tools commonly available to large-scale farming. Weed control was done by hand, also simulating the conditions of rural farmers.

This field research took place over one growing season in the remote Huamburque area in the southern Peruvian department of Ayachucho in the Andean Amazon basin. Elevations ranged between 3,000 and 4,000 meters. Crops grown there support rural nearby villages, but a portion of the yield is also sold in large population centers such as Lima and Cusco.

The researchers said they expected corn and potato farmers in Andean regions of Colombia, Ecuador, and Bolivia to experience the same challenges.

More than 4,000 varieties of native potatoes grow in the Andean highlands and many Andean people rely heavily on potato production. Photo by Saúl M. Tito.

“We need to do more experiments in more places with more crops,” Feeley said. “But there is no reason to think these results are unique. We’re already hearing about farmers moving their coffee and chocolate crops higher upslope because of warming temperatures.”

For Tito, who grew up in the Peruvian Andes and for whom Spanish is his second language, this research held a special importance. Agricultural experiments related to climate change are often done in greenhouses under controlled conditions, but Tito was able to gain the trust of the Andean farmers and conduct the research in their fields under actual climatic conditions.

“I am a member of the local community and I know the study area, the local farmers and their rich traditional knowledge,” said Tito, who recently received his PhD from the Instituto de Biologia at the Universisdade Federal de Uberlandia in Brazil. “Because the population is skyrocketing, climate is changing and the impact on food production is a real threat, a real motivation for me in this research is to recommend effective management strategies.”

Severe attacks by stem-borer caterpillars on potato plants have grown under warmer temperatures. Photo by Richard Tito.

Feeley said that for these rural farmers in remote Andean regions that are difficult to access, there are some options. Peru has an enormous variety of corn and potatoes, and he recommended farmers try shifting to varieties that may be more tolerant of warming temperatures. Because of limited funds, these farmers aren’t likely to buy commercial fertilizer, pesticides, or genetically modified seeds (GMOs). Irrigation is also unlikely.

Peru’s international agricultural center also studies potato production and is actively looking for solutions to protect crops from climate change. Feeley said he hopes experts there will reach out to remote, rural farmers with assistance.

“It’s always important to stress that climate change is having and going to have real impacts on lots of people through food,” Feeley said. “And what we found is that relatively small changes in temperature can have a huge effect on the livelihoods and health of millions of people.

“If people can’t live in these rural areas because of reduced food production, they will move to the cities and you will have more urban slums. Rural farmers are going to need help adapting. We really want to avoid more climate refugees moving around within countries.”

A typical potato farm where can you see different color of flowers indicating different varieties grown in the same plot. Photo by Saúl M. Tito.

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Justin Catanoso is a regular contributor to Mongabay and a professor of journalism at Wake Forest University in North Carolina USA. Follow him on Twitter: @jcatanoso.