California Gov. Jerry Brown sat in the front row and listened intently as five scientists, including Stanford Professor Rosamond Naylor, presented compelling data on potential climate change impacts to several hundred scientists on Wednesday (Dec. 11) at the American Geophysical Union’s fall meeting in San Francisco.

At the end of the session, Brown urged the audience to translate the scientific conclusions into understandable terms in order to build widespread support for addressing climate change. “We’re, I think, without overstating it, doing more than any place I know,” Brown said, referring to California’s renewable energy investments. “We have to have other states, other countries, be a part of this effort. The political response has to be international.”

At the session Brown attended, “Abrupt Impacts of Climate Change: Anticipating Surprises,” Naylor explained how climate shocks, such as El Nino events, or temperature extremes, can lower crop production and cause food prices to rise, often leading governments to intervene in trade in ways that make global food prices even more volatile. In the rice market, a strong El Nino event can cause international prices to jump by 20 percent, she noted, and there is large variability in price movements due to government policy.

It is not uncommon for countries to experience riots when food prices spike, particularly poor countries where individuals spend the majority of their income on food. Naylor attributed the lack of food riots in the United States to the “giant safety net program—SNAP (food stamps)—which most countries don’t have.”

Naylor, who is director of Stanford’s Center on Food Security and the Environment and a senior fellow with the Stanford Woods Institute for the Environment, also discussed her ongoing research with David Battisti, a professor of atmospheric sciences at the University of Washington, that is focused on grain yield variability in the mid-latitudes.

As summertime heat waves become more common, she said, international food supplies will become  more stressed because mid-latitude countries tend to play a dominant role in international markets. Even a steady increase in average growing season temperature can lead to high variability in crop yields, she said: “We don’t need to have abrupt climate change to be very, very worried about global food security.”

Naylor described three main options available to farmers to reduce yield loss with rising temperatures: (1) grow shorter-maturity crop varieties, which would result in losing some crop yield potential, (2) plant crops earlier, which depends on precipitation and whether farmers can get into the fields to plant, and (3) use new crop varieties that can withstand higher temperatures.

Naylor provided evidence from her work with Battisti to show why aggressively breeding heat-tolerant varieties, both conventional and genetically modified types, is likely to be the only effective option, but will also take time, vision and money. Even with such breeding, there is still variation in rainfall and in pest and pathogen stresses to worry about.

“Are we going to have more hunger? Are we going to have more conflict?” she asked. “I think it’s worth having a conversation about it.”

The two-hour session was convened by Anthony Barnosky, an integrative biology professor at the University of California at Berkeley, and James White, a geological sciences professor at the University of Colorado at Boulder.