These Beans Can Handle Climate Change

Beans for sale in the old City of Harar in Eastern Ethiopia
Beans for sale in the old City of Harar in Eastern Ethiopia Photo: Toby Adamson / Design Pics

Beans have a reputation as a magical fruit, but they're also hugely important to the world's food supply: Because they're rich in fiber, protein, complex carbohydrates, and vitamins, beans are a daily staple for more than 400 million people.

But beans won't do so well when the world heats up — thanks to climate change, rising temperatures might wipe out bean growth by 50 percent. When Steve Beebe, the head bean researcher (yes, there is such a thing) at the International Center for Tropical Agriculture saw the numbers, his team began searching for a variety that could withstand the heat. And they found one — it was just sitting in their lab.

A cross between a tepary bean, which is a heartier strain grown in pre-Columbian times in Mexico and the Southwest, and a normal bean, this variety can withstand up to a three degrees Celsius increase in temperature over the next 100 years. We talked to Beebe about why this find is so important and what happens next.

How did you come up with the idea to cross a tepary bean with a normal variety of bean?
The cross had been made more than ten years ago by another colleague, but he left the materials on the shelf in the cold room. So we had these materials right under our noses, but until we started worrying about high temperatures, we didn’t realize it. We got lucky.

How do these beans taste?
We don’t know.

You don’t know?
We haven’t eaten them yet.

Is that a trivial question?
It’s not trivial; I think especially small farmers are very conscious of how their food tastes. I’d sure like to start screening beans more systematically for flavor. They’re nutritious, but at the end of the day, they all have to be eaten, and if they don’t taste good, the consumer won’t be back.

How does the yield of these beans compare to a regular crop?
Under bearable conditions, a single crop of both the normal beans and the heat-tolerant beans can yield around one ton per hector. But in one yield trial that we ran under high temperatures, regular type yielded absolutely nothing.

What causes the beans to die?
Some plants are cross-pollinated, which means they have a male part (the pollen) and a female part. But beans are self-pollinated, which means that inside every flower is both pollen and an ovule. So pollination occurs inside the flower, and that process happens at night, and it's very sensitive to temperature.

Now that you’ve developed these heat-resistant beans, what’s next?
First, we distribute them to research programs in warm areas. Then the materials are tested for yield, and if they’re superior we have to register them in each country. Then they go into seed production and are put up for sale. Usually a public institution distributes them. Seed companies don’t have much interest in selling bean seeds, because farmers can receive the seeds, and plant, and keep their own seeds year after year after year.

Can what you learned here apply to, say, drought-resistant corn?
Probably not, because they’re very different species. Corn is cross pollinated, and corn doesn’t have a sister species with which it can be crossed. There are 60 or 70 different species of beans that have been identified, which gives us a lot of flexibility in terms of what sorts of environments and what sorts of stressors we can try to accommodate.

What other challenges will beans face in regards to climate change?

Beans are very sensitive to excess water, so too much rainfall will be hard for farmers to deal with — often excess water in the soil leads to fungal disease. And soil is a really big issue because tropical soils are much poorer than soils in the temperate zones. We also have drought. Basically there’s a whole suite of problems that’s going to come from climate change.