Around 9,000 years ago, human beings began growing corn for the first time near Tehuacan, in what is now the central Mexican state of Puebla.

In the years that followed, corn became an important part of the cultures that gave rise to modern Mexico.

Now, climate change threatens corn production in the area.

Sol Ortiz is director of the climate change group at Mexico's agriculture ministry. Ortiz says that 75% of Mexico's soil is already too dry for growing crops. In areas such as Tehuacan, temperatures may rise more than the average increase worldwide.

Porfirio Garcia's dry corn field is seen in Tepeteopan, state of Puebla, Mexico January 16, 2020. Picture taken January 16, 2020. REUTERS/Carlos Jasso

"We know there are areas where the increase is going to be greater. That will obviously affect rain patterns, and in turn, agriculture and food security," Ortiz said.

In Tehuacan, the area under corn cultivation decreased 18% between 2015 and 2019, to about 40,000 hectares, the Reuters news agency reported.

Nationally, the area under corn cultivation declined 4% from 2015 to 2019.

Farmers decide to change the crops that they grow for many reasons. But in Tehuacan, one important reason is a fast-changing climate, farmers and local officials say.

On one especially dry field, Profirio Garcia uses ancient farming methods to grow corn, beans and pumpkin.

"The corn harvest has shrunk because in the months of June, July, August and September there was no rain," Garcia said. "Our lives center on corn, so what do we do without it?"

Eusebio Olmedo, director of rural development, agriculture and livestock in Tehuacan, says it began to get hotter at the turn of the century.

Last year was the warmest on record in the Mexican state of Puebla, where Tehuacan is located. Temperatures reached an average high of 26.8 degrees Celsius. In 1985, the first year available for state records, Puebla registered an average high of 24.7 degrees Celsius.

In Mexico's north, climate change may, at first, have little effect, studies show.

But in the south, where the oldest corn strains on earth are grown using traditional methods, the changing temperatures and rainfall levels are being felt.

Mexico, due to its dependence on grain from the United States, is now the world's second-largest corn importer. President Andres Manuel Lopez Obrador calls that dependency "a contradiction" and has started programs to increase national production.

Agricultural advisory service GCMA estimates that Mexican corn production will continue to fall in 2020. Corn imports, mainly from U.S. growers, will reach a record 18 million tons, the group notes.

Garcia chose to diversify his crops. He planted 300 trees of pistachio, a desert plant that can survive in temperatures between minus 10 and 40 degrees Celsius.

Nearby farmer Natalio De Santiago stopped growing the corn that he, his father and his grandfather used to plant. He now grows crops that require less water.

"I stopped sowing (corn) because the weather is changing," said De Santiago. "Now I plant maguey because it needs less water."

Maguey is used to make alcoholic drinks.

De Santiago said he provides a liter of water every month to each of his 400 maguey plants. When he planted corn, he said, his crops needed four months of rain.

In an attempt to stop the decline in corn planting, local officials developed a bank of native corn seeds. The seeds are more resistant to insects and other pests. They also need less water.

"We have to adapt to climate change, and these are the best varieties to recover food self-sufficiency," Olmedo said of the seeds.

The government has also promoted alternative crops and launched campaigns to reduce agricultural burning, among other measures.

"It is very difficult to end the tendency to increase production of carbon dioxide in the atmosphere," said the agricultural ministry's Ortiz.

Studies have shown a link between rising carbon dioxide levels and rising temperatures on the planet.

"Climate change is here to stay," Ortiz added.

And I'm John Russell.

Diego Oré reported on this story for Reuters. John Russell adapted the story for VOA Learning English. George Grow was the editor.

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