CO2 Helps Crops Withstand Drought

CO2 Helps Crops Withstand Drought
March 24, 2014

Isaac Orr

Isaac Orr is a research fellow at The Heartland Institute. He previously worked as a research... (read full bio)

California is in the midst of a multi-year drought that is putting pressure on water supplies in cities and causing some farmers to reduce acreage and cull their herds.

Growing up on a dairy farm in the middle of Wisconsin, I learned the importance of having enough water, sometimes the hard way. Our farm was particularly at risk because when the glaciers receded they left a type of soil that my grandfather refers to as “blow sand.” Some years we would get a crop, and some years the crops would all dry up, but that’s farming.

The drought in California is likely due to natural variations in climate, not human activity, according to Edward Cook, director of the Tree Ring Laboratory at Columbia University’s Lamont-Doherty Earth Observatory. Unfortunately, that has not stopped politicians from blaming human emissions of carbon dioxide for the drought.

A new book released by the Nongovernmental International Panel on Climate Change (NIPCC) finds higher levels of carbon dioxide in the atmosphere actually help plants survive droughts, which is good news for everyone, especially people in the developing world.

The book, Climate Change Reconsidered II: Biological Impacts (CCR-IIb), just published by The Heartland Institute (where I work), demonstrates increased atmospheric CO2 concentrations (also known as CO2 enrichment, a technique commonly used in greenhouses) helps key staple crops use water more efficiently and thus withstand the dry times.

Chapter 2 explains, “As the CO2 content of the air continues to rise, nearly all agricultural plants will respond favorably by exhibiting increases in water use efficiency. It is also thus likely food and fiber production will increase on a worldwide basis, even in areas where productivity is currently severely restricted by limited availability of soil moisture.”

Among the key staple crops found to respond favorably to CO2 enrichment are potatoes, soybeans, and wheat. That is vitally important because global populations are projected to increase by 1 billion people in the next 12 years, with the growth largely coming from developing countries. As populations expand, increasing numbers of people move to the cities to look for work, placing stresses on food supplies. Multiple studies have demonstrated that historically, potatoes have played a major role in feeding countries undergoing urbanization and industrialization.

Citing a study by Olivo et al. (2002), CCR-IIb demonstrates potatoes grown at 700 parts per million (ppm) CO2 (approximately 300 ppm higher than current levels) can increase their water efficiency by up to 90 percent. These findings could have major implications for the feeding of rapidly expanding and industrializing countries in the future.

Demand for soybeans has expanded rapidly as the Chinese population has urbanized and become more affluent, fueling a demand for meat. Soybeans feed pigs, and “pork is China’s meat of choice, accounting for nearly three fourths of its meat consumption.” CCR-IIb notes soybeans grown at 700 ppm CO2 lost 10–25 percent less water during transpiration while increasing dry weight by as much as 33 percent, meaning soybeans become more productive while consuming less water.

Finally, wheat grown at 550 ppm CO2 improved its water use efficiency by one-third over plants grown at 370 ppm CO2. This is a particularly important finding considering wheat provides more nourishment for humans than any other food source.

Instead of making food scarcer, CCR-IIb finds increased levels of atmospheric carbon dioxide will make crops in drought-stricken areas, such as California, more productive while using less water.

In addition to consuming more food, people in developing countries will want clean water, electricity, and other basic products considered necessities in the developed world. These needs will realistically be met by burning coal, a key producer of carbon dioxide.

Thankfully, the extra food produced by rising atmospheric carbon dioxide can help fill empty stomachs both at home and abroad.

Isaac Orr

Isaac Orr is a research fellow at The Heartland Institute. He previously worked as a research... (read full bio)