NYT: A Warming Planet Struggles to Feed Itself
In our study of the costs of climate change in the United States, “Pay Now, Pay Later,” we warned about what a changing climate would mean for agriculture, among other things. Throughout the work, however, we had to reconcile the fact that higher CO2 concentrations should, in theory anyway, increase agricultural production. From high school biology we all remember that plants scrub CO2 from the atmosphere and use photosynthesis to produce glucose that fuels their growth. If there were more CO2 in the atmosphere, the theory went, then plants would have an easier time growing.
We know now, however, the science is increasingly dubious on this point. In fact, it appears that climate change will make agriculture more difficult around the world, and not just in tropical regions.
Consider this story from the New York Times, “A Warming Planet Struggles to Feed Itself.”
Sitting with a group of his fellow wheat farmers, Francisco Javier Ramos Bours voiced a suspicion. Water shortages had already arrived in recent years for growers in his region, the Yaqui Valley, which sits in the Sonoran Desert of northwestern Mexico. In his view, global climate change could well be responsible.
“All the world is talking about it,” Mr. Ramos said as the other farmers nodded.
Farmers everywhere face rising difficulties: water shortages as well as flash floods. Their crops are afflicted by emerging pests and diseases and by blasts of heat beyond anything they remember.
In a recent interview on the far side of the world, in northeastern India, a rice farmer named Ram Khatri Yadav offered his own complaint about the changing climate. “It will not rain in the rainy season, but it will rain in the nonrainy season,” he said. “The cold season is also shrinking.”
The scientists working this issue have struggled to explain why increased atmospheric carbon dioxide does not seem to increase crop yields. The explanation can be found, they believe, in the fact that higher CO2 concentrations do not occur in isolation, but are also accompanied by higher temperatures as well as disrupted precipitation patterns producing either too much or too little rain. The Times provided details of research done over the last decade at the University of Illinois:
When they grew the soybeans in the sort of conditions expected to prevail in a future climate, with high temperatures or low water, the extra carbon dioxide could not fully offset the yield decline caused by those factors.
Their work has contributed to a broader body of research suggesting that extra carbon dioxide does act as plant fertilizer, but that the benefits are less than previously believed — and probably less than needed to avert food shortages. “One of the things that we’re starting to believe is that the positives of CO2 are unlikely to outweigh the negatives of the other factors,” said Andrew D. B. Leakey, another of the Illinois researchers.
The Times continued:
Two economists, Wolfram Schlenker of Columbia University and Michael J. Roberts of North Carolina State University, have pioneered ways to compare crop yields and natural temperature variability at a fine scale. Their work shows that when crops are subjected to temperatures above a certain threshold — about 84 degrees for corn and 86 degrees for soybeans — yields fall sharply.
This line of research suggests that in the type of climate predicted for the United States by the end of the century, with more scorching days in the growing season, yields of today’s crop varieties could fall by 30 percent or more.
Scientists are racing against the clock to provide sustainable solutions to these challenges. Farmers face the need to increase production as the world’s population races to 9 billion people by 2050 while climate change exerts downward pressure on crop yields.
Let your mind wander over that witch’s brew for a minute.
This is principally a challenge for agricultural scientists, but one that can’t be addressed without public policies that support the investment in, and eventual distribution of, seed stocks better suited to the growing conditions we can expect to see around the world.
I wish I could say that there is hope that we might mitigate some of the worst of climate change. At the moment, unfortunately, the politics in the United States and elsewhere look increasingly like we’re going to have to concentrate on adapting to a changed planet.
