Scientists call for food production changes to avoid climate impact

The global agricultural industry needs a major revision if the world is to meet climate change targets according to new research from the University of California.

In a paper published in the journal Science, lead author ecology professor David Tilman of the UC Santa Barbara has warned reducing fossil fuels alone will not be enough to meet global temperature reduction targets.

The biggest issue is the way in which the world produces its food.

“Global food demand and the greenhouse gases associated with it are on a trajectory to push the world past the one-and-a-half degree goal, and make it hard to stay under the two degree limit,” said Prof Tilman, who holds a dual appointment at UCSB’s Bren School of Environmental Science & Management and at the University of Minnesota.

He explained the world’s growing population as well as its diet are driving food production practices that generate and release massive and increasing amounts of carbon dioxide, methane and other greenhouse gases into the atmosphere. According to the paper, left unchecked, agricultural emissions alone could exceed the 1.5°C limit by about 2050.

“All it would take for us to exceed the two-degree warming limit is for food emissions to remain on their path and one additional year of current fossil fuel emissions,” Prof Tilman said. “And I guarantee you, we’re not going to stop fossil fuel emissions in a year.”

Reducing the emissions from food production, “will likely be essential” to keeping the planet liveable in its current state, according to the scientists.

“It’s well known that agriculture releases about 30% of all greenhouse gases,” Prof Tilman said. Major sources include deforestation and land clearing, fertilizer overuse and gassy livestock, all of which are increasing as the global population increases. In “high-yield” countries such as the U.S., which have the benefit of large-scale modern agriculture, intensive animal farming and heavy-handed fertilizer use are major contributors of greenhouse gases. Meanwhile, in “low yield” countries such as those in sub-Saharan Africa, population growth and increasing affluence are driving demand for more food, and toward more “urban” diets that are richer in meat and meat products, Tilman explained.

“Their demand for food is going up, but the farmers don’t have the resources to have high yields, so they just clear more and more land,” he said.

Prof Tilman explained: “You can’t look at agriculture as if we can somehow get rid of it.”

But, according to the paper’s authors, global warming does not have to be an unavoidable impact of feeding the world. Through early and widespread adoption of several feasible food system strategies, it is possible to limit emissions from agriculture in a way that keeps us from exceeding the 2°C limit by the end of the century while feeding a growing population.

The most effective, according to the paper, is a switch toward more plant-rich diets, which aren’t just healthier overall, but also reduce the demand for beef and other ruminant meats. That, in turn, reduces the pressure to clear for grazing land or produce the grains and grasses (more farming, more fertilizer) required to feed them.

“We’re not saying these diets have to be vegetarian or vegan,” Prof Tilman said. Widespread reduction of red meat consumption to once a week and having protein come from other sources such as chicken or fish, while increasing fruits and vegetables, in conjunction with decreasing fossil fuel use, could help keep the planet at temperatures that sustain life in the long run.

Other strategies the researchers explored included adjusting global per capita calorie consumption to healthy levels; improving yields to help meet demand where it may reduce the pressure to clear more land; and reducing food waste by half.

“The nice thing is that we can do each of these things sort of halfway and still solve the problem,” Prof Tilman said. The sooner we employ these strategies, the closer we can get to keeping the Earth cool and avoiding the wholesale changes we would have to adopt if we wait too much longer, he added.

“I’m optimistic,” he said. “We have a viable path for achieving global environmental sustainability and better lives for all of us.”