Helping climate science make sense.

Climate Change Could Shift the Landscape for Agriculture

Three Things You Should Know

1) Climate has an important influence on farming, so as the global climate changes it will have an affect on which areas of the world have land that is suitable for agriculture.

2) By 2100, new research predicts that we should expect the amount of land that can be used for agriculture in the U.S. and Canada, Russia, and northern China to increase significantly. On the other hand, the area suitable for agriculture in Africa and South American could shrink by almost 20 percent, which has important implications for growing populations in these areas.

3) Even though more land in the U.S. is predicted to be conducive for agricultural uses, a mix of global economics, politics and population changes will dictate how much of that land actually gets developed.

A woman in Zanzibar plants sweet potato. Credit: murkas/flickr

The Debrief:

In recent years, there has been a lot of research looking at how climate change may influence agricultural production. Most studies have focused on how crop yields might change as temperatures increase and precipitation patterns shift. Because plants rely on carbon dioxide (CO2) in the atmosphere for photosynthesis, you might think that plants will thrive with all the extra CO2 out there.  But scientists now know many of the other changes caused by increasing greenhouse gases — like rising temperatures and altered water availability — actually offset the benefit of having more CO2 available for many important crops.

Generally speaking, crop yields around the world are probably going to fall as the planet warms up.

Climate change could also play a part in which regions of the world are best for growing crops or raising livestock. In a new study, researchers from the University of Illinois at Urbana-Champagne have examined where ideal land for agriculture is now and where it will be by the end of this century, based on global climate model predictions of the planet’s temperatures, humidity, and other variables.
 
Engineering professor Ximing Cai and his student Xiao Zhang analyzed all of the land on Earth in terms of how suitable it is right now for some kind of agriculture.

What makes land just right for agriculture, you ask?

The terrain matters (farming on flat land is a whole lot easier than farming on a steep hill), and so does soil quality. But climate is a key component, too. For crops to grow (including grass for livestock grazing), it can neither be too hot nor too cold, too wet nor too dry. All crops have their own ideal climate but generally speaking there are parts of the world with climate conditions that are more conducive to agriculture than others. 

Using a collection of global climate models, Cai and Zhang assessed how the climate is going to change around the world over this century, and then region-by-region they estimated how those variations might affect the agricultural potential of the area. They found that, in some regions, there could be substantial shifts in land use. The findings of their study are published in the journal Environmental Research Letters.

“In areas at high latitude, like in parts of the U.S., Russia, and northern China, a lot more land will become available,” says Cai. “But in the tropics and sub-tropics, in India, Africa, and South America, those regions might experience a large decline in suitable land.” This is due to the high latitude regions becoming warmer and receiving more moisture through increased rainfall, while lower latitude regions are expected to become too hot, too dry, or both.

Overall, he says that there isn’t going to be a significant change in the total land available for agriculture on the planet, but the regional changes will be substantial. For example, the U.S. could see an increase in farming-appropriate land of between four and 17 percent. And Cai says China can expect an increase of arable land of between 37-67 percent.

Farmland from above in Pennsylvania. Credit:  Dr.DeNo/flickr

On the other hand, in Africa and South America, which today comprise 40 percent of the world’s potential agricultural land, climate change could leave up to 20 percent of the land unsuitable for farming. The range of changes that Cai and Zhang calculated reflects different future emissions scenarios and ways of combining projections of the future climate from several models.

Why This Science Matters

The fact that different regions of the world are expected to have large variations in how much land becomes or remains suitable for agriculture “could affect the future of food production and demand around the world,” says Cai.

Man-made climate change has already been implicated in the supply of some of the world’s favorite foods. In South America, some farmers and scientists say that climate change is to blame for the dwindling yields of coffee crops observed over the last several years. As the tropics get even hotter over the rest of the century, coffee trees might not continue to thrive in the regions most famous for them.

Within the United States, there are also bound to be changes in which areas are suitable for farming. As global temperatures rise, the southern states that produce everything from cotton and tobacco to vegetables and citrus fruits may become less arable. And the conditions that support the nation’s breadbasket, the Midwest’s vast expanse of wheat and cornfields, are expected to migrate further northward.

So, how much of the world’s lands can be used for agriculture depends largely on the climate. But Cai quickly acknowledges that how much of the land will be used for agriculture will be dictated by several other complicating factors, like global economics, politics and population change.

Food prices are heavily influenced by supplies. As we’ve seen in recent years, extreme weather and climate events, like heat waves, droughts and floods, can have a drastic impact on global supplies, and that can really drive up the cost of even the most basic food, like wheat and corn. But supplies aren’t the only things that affect the cost of food around the world. As Stanford University researcher David Lobell explained in a Q&A with Climate Central:

“Food prices are determined by all kinds of things. People change their food preferences and their incomes can change as the global economy fluctuates. Global trade agreements come and go and the demands for biofuels derived from certain crops go up and down.”

How global population and international trade agreements affect the demand for agriculture in the future is still largely a mystery, although researchers like Lobell are refining their predictions. But regardless of how all these other puzzle pieces fall into place, Cai’s research now shows that the basic outline of where crops can be grown is bound to change in the coming decades. 

« Climate in Context