Negotiators for the world's governments signed off on a report Wednesday that describes in alarming detail how agriculture, deforestation and other human impacts on lands are transforming the climate.
The report, from the United Nations' Intergovernmental Panel on Climate Change (IPCC), shows the urgent need to overhaul the global food system to help control climate-warming emissions.
Written by more than 100 scientists from around the globe, it takes an unprecedented look at the impacts of climate change on lands and the effects of land use on the climate.
The authors say that the entire food production system, with transportation and packaging included, accounts for as much as 37 percent of total greenhouse gas emissions, and that better land use, less-meat-intensive diets and eliminating food waste should be global priorities, crucial to the immediate, all-out effort needed to forestall a climate catastrophe.
"There's no doubt the window is closing rapidly," said Pamela McElwee, one of the report's authors and a professor of human ecology at Rutgers University. "That's a key message of this report."
Negotiations over the final wording of the report, which was written after assessing thousands of studies, began in Geneva last week. Attendees said the talks were bogged down at times by negotiators from countries, including the United States, with powerful biofuels and livestock industries. Still, the report that emerged was clear that diets high in meat have a bigger carbon footprint and that biofuels can compete with food production.
The authors had the daunting task of assessing the impact of agriculture and deforestation on the climate, and the equally challenging job of outlining ways that better land management can provide solutions to the climate crisis.
The report, released to the public on Aug. 8, shows that stopping deforestation, limiting greenhouse-gas-emitting fertilizers and raising crops in ways that add carbon to the soil are essential for achieving global goals for controlling rising temperatures.
Currently, global lands absorb more carbon than they emit. But that will change if land degradation and deforestation continue, the report warns.
"The amount of greenhouse gases emitted in the future really depends on the choices we make today," said Louis Verchot, one of the report's lead authors and a researcher with the International Center for Tropical Agriculture. He noted that greenhouse gases from lands are increasing, especially with a recent uptick in deforestation in Brazil and other South American countries. "Could land shift from a sink to a source? We know that's very much a possibility."
[Read more about climate change on the American farm and what's preventing better practices there in the award-winning ICN series Harvesting Peril]
Effects of More Intensive Farming
Most of the carbon stored in the planet's land is in natural landscapes, not those managed as farmland or forests.
"If we continue to degrade ecosystems, if we continue to convert natural ecosystems, we continue to deforest and we continued to destroy our soils, we're going to lose this natural subsidy that we're getting that's protecting us in part from ourselves and from the damage that we're creating as we pump these greenhouse gases in the atmosphere," Verchot explained.
Since the early 1960s, global population growth and more intensive farming have led to "unprecedented rates of land and freshwater use," the report said. Human activities, including farming and other land uses, impact nearly three-quarters of the global land surface. Meat production has more than doubled, and the supply of calories per person has increased by one-third.
But the agricultural developments that helped propel the world's population are now some of the same ones that need to be retooled.
As the population has grown, emissions related to agriculture have also grown, largely because of increases in livestock, deforestation to clear land for crops, and fertilizer use.
Agriculture and deforestation account for 23 percent of global greenhouse gas emissions. But the report says that if the entire spectrum of food production were factored in—from growing crops to transportation and packaging—that percentage could be as high as 37 percent.
Solutions: Diet Changes, Sustainable Farming
Climate change is already having severe effects on agriculture, with more drought and extreme downpours. That has threatened food security, in part because it drives down crop yields.
That will likely get worse, especially in tropical and subtropical parts of the world, the report says. In some regions, extreme weather fueled by global warming could lead to "increased displacement, disrupted food chains, threatened livelihoods ... and contribute to exacerbated stresses for conflict."
The potential risk for "multi-bread-basket failure," with climate disasters hitting more than one major agriculture region at the same time, is increasing, said Cynthia Rosenzweig, one of the report's lead authors and a senior research scientist at the NASA Goddard Institute for Space Studies.
The authors point to a suite of solutions for reducing agriculture's impact on climate change, including farming more sustainably—using less fertilizer, lowering tillage and employing practices that increase the soil's ability to hold carbon—as well as reducing higher-impact diets.
"Diets present major opportunities for reducing greenhouse gases as well, because diets that are rich in plant-based foods emit lower greenhouse gases than diets that are very heavy in red meat consumption," Rosenzweig said. The report's authors conclude that, by 2050, dietary changes could free up hundreds of millions of acres of land, which could help avoid deforestation and reduce emissions.
The report is the latest in a series of high-profile publications pointing to meat consumption, particularly of beef, as a significant contributor of greenhouse gases. Not only do cattle emit methane, but beef production also leads to deforestation for grazing lands and cropland to grow feed for livestock.
The authors say reducing food waste is another key strategy for cutting emissions from the food system. Nearly a third of the food produced in the world is lost or wasted.
Worsening Climate Change Puts Crops at Risk
The report underscores the urgency for using land-based solutions to tackle climate change, which can have a big impact but have to be accomplished in a relatively short time frame. As the climate heats up, crop yields will continue to drop while farm fields lose their ability to store carbon.
Some of the solutions, including large-scale tree-planting on previously unforested land and using land to grow biofuels, present trade-offs because they threaten to compete with land for growing food crops.
The authors outline various scenarios in which global population and resource consumption rises or falls. The most optimistic scenario, in which fewer resources are consumed and more people adopt "low greenhouse gas" diets, would translate to lower emissions and help keep global temperatures from rising more than 1.5 degrees Celsius above pre-industrial levels—the aim of the Paris climate agreement.
"It's a critical report right now," said Doreen Stabinsky, a professor of global environmental politics with the College of the Atlantic, who was in Geneva to observe the final negotiations over the report. "There's been increasing recognition about the climate change impacts on land and food, and there's a recognition that it's all-hands-on-deck."
The IPCC plans to release another report, this one exploring the relationships among climate change, oceans and frozen landscapes, or the "cryosphere," this fall.
Published Aug. 8, 2019