In the effort to keep the planet from reaching dangerous temperatures, a hybrid approach called BECCS (bioenergy with carbon capture and storage) has a seductive appeal. Crops suck carbon dioxide (CO2) from the atmosphere, power plants burn the biomass to generate electricity, and the emissions are captured in a smokestack and pumped underground for long-term storage. Energy is generated even as CO2 is removed: an irresistible win-win. But, the United Nations’s climate panel sounded a warning about creating vast bioenergy plantations, which could jeopardize food production, water supplies, and land rights for poor farmers.

In an earlier special report in October 2018, IPCC called for holding the rise in global average temperatures to no more than 1.5°C above preindustrial conditions to avoid the worst consequences of climate change. It emphasized that cutting emissions won’t be enough to reach that goal. Replacing coal with renewable energy, and significantly cutting oil and natural gas, would still leave gigatons of excess carbon in the atmosphere. BECCS could remove it, computer models suggested, if several million square kilometers—an area the size of India—were devoted to energy crops.

But the 2019 IPCC report examines the consequences of deploying BECCS on that vast scale and concludes it could “greatly increase” the demand for agricultural land. The pressure on conventional crops could compromise food security, as happened in 2007 when rising U.S. corn ethanol production contributed to a spike in food prices. (In Mexico, the price of tortillas, a staple for the poor, rose 69% between 2005 and 2011.) The bioenergy plantations could also take a toll on biodiversity—as is happening in Southeast Asia, where plantations producing palm oil for biodiesel as well as food are displacing diverse tropical forest. And they could suck up scarce water, especially in drylands, where irrigation of crops might deplete local supplies, the IPCC report says.

Industrial bioenergy crops can lead to the same kinds of problems as intensive food production, such as the contamination of water from excess fertilizer. Scaling up bioenergy in developing countries can also exacerbate social problems like the loss of land by small farmers.

Excerpts from Erik Stokstad, Bioenergy plantations could fight climate change—but threaten food crops, U.N. panel warns, Science, Aug. 8, 2019