Climate poses big threat to crop production, new study says
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Adaptation can't outrun climate change, and rich farming nations — including the U.S. — face jeopardy despite their resources, according to a major new paper on global warming and crop production.
Why it matters: It's the first look at climate effects on staple crops to weigh farmers' "real-world adaptation measures" and fold them into projections of future damage, a summary states.
- The Nature paper projects losses for all staples analyzed except rice, though there's lots of regional variation.
The big picture: The paper estimates that for every 1°C of temperature rise, global food production capacity falls by 120 calories per day per person.
- "If the climate warms by 3 degrees, that's basically like everyone on the planet giving up breakfast," said co-author Solomon Hsiang, a Stanford environmental policy professor, in a statement.
- Hot and relatively low-income regions are showing more adaptation to date than wealthier breadbaskets in more moderate climates. That's one reason future risks are so high.
State of play: The authors analyze over 12,600 regions in 54 countries, looking at six staple crops — corn, soybeans, rice, wheat, cassava and sorghum.
- It's "one of the most comprehensive samples of subnational crop yields ever assembled," the study states.
- It sees future gains in some areas, but declines on a global basis for most crops.
Threat level: One reason for the conclusions? Realism.
- A clear-eyed look at how farming evolves is needed, the paper states, comparing its work to prior models that assume optimal responses.
- In reality, financial constraints, market failures, human error and more influence farming.
What they found: Under a moderate emissions growth case, central estimates in 2100 — with adaptation and income growth — are -12% for corn, -13.5% for wheat, and -22.4% for soybeans, to name three.
- But the uncertainty bands are quite big because they're looking well into the future.
What's next: Adaptation and higher wealth alleviate 6% of global losses in 2050 and 12% in 2100 in that moderate emissions scenario.
- That's RCP 4.5 for you wonks out there, which still sees enough emissions to warm the world beyond Paris Agreement targets.
- The paper also explores a runaway emissions case (RCP 8.5), though many scientists no longer consider this CO2 growth likely.
Zoom in: Check out the country-level projections for various crops.
- The paper estimates that even with adaptation, parts of the U.S. could see corn and wheat declines in the 25% range in the moderate emissions case. Here's the same map under runaway emissions.
- Nearer term, climate change will drag global crop yields down by 8% in 2050, "regardless of how much emissions rise or fall in the coming decades," a separate Stanford summary notes.
The bottom line: Adaptation to a hotter world is important and helps temper crop losses — but it has its limits.
