Research scientist, Dr. Jeff Schussler claims that slight increase in atmospheric CO2 — as well as increased sunshine hours observed in North America — have meant “peculiarly pleasant weather” for corn and soybeans over the last 40 years.
Nelson Zandbergen
Farmers Forum
For decades, the farmers of Canada and the U.S. have enjoyed ever increasing yields, and a lot of that extra bounty is due to a slight increase in global warming and extra sunshine, says Iowa-based plant physiologist and research scientist Dr. Jeff Schussler. He also predicts the upward trend will continue as science continues to develop plant varieties best suited to the conditions.
“I’m very impressed by what we’ve done in our lifetimes and I’m very optimistic about what we’re going to do in the next generation in trying to provide food security for the world,” Schussler, a consultant who worked 20 years for Pioneer and Corteva, noted in an upbeat talk about the “positives of climate change” at the January 2023 Ontario Agricultural Conference, held online and in person at Kemptville, Ridgetown and Waterloo.
North American farmers will play an even greater role feeding the hot, equatorial parts of the planet where global warming is having a disproportionately negative impact, he acknowledged. “Just be aware not everybody in the world is going to have a great scenario in front of them … We are in a good position.”
Backed up by slide after slide of published research, Schussler demonstrated how a slight increase in atmospheric CO2 — as well as increased sunshine hours observed in North America — have meant “peculiarly pleasant weather” for corn and soybeans over the last 40 years. The growing season added 9 or 10 days during the period, helping take corn yields from 105 bu/ac in 1981 to nearly 175 bu/ac in 2017. About 28 % of that increase can be attributed to the overall “better weather,” according to University of California researchers.
Dr. Jeff Schussler
Other researchers found that the extra sunshine alone — also known as “solar brightening” and apparently unique to North America — accounts for 27 % of the increased corn belt yield between 1984 and 2013. Schussler could offer no explanation for the increase in sunshine but pointed out that corn and soybean fields are like solar panels. More sun means more production.
As for the man-made rise in carbon dioxide, from about 410 parts per million (ppm) in 1970 to about 425 ppm today, Schussler said the change hasn’t produced an average rise in maximum daily temperatures in the U.S. and Canada. In fact, daily maximums have fallen one to two degrees in the U.S. corn belt, in part because of the moderating effect of those millions of corn and soybean acres, he said. Meanwhile, the average temperature of the globe has gone up only about 0.8C since 1900.
The daily maximum temperature is a greater concern to farmers because it’s a gauge of the extremes that can cut corn and soybean yields — although those species do thrive in hot weather generally. Ironically, the extra CO2 in the atmosphere makes it easier for those crops to tolerate higher temperatures anyway, he said, because it slows water loss from the leaves through transpiration. “So it (CO2) actually makes crops more water-use efficient…. We call that an indirect CO2 fertilization effect. And that’s especially effective under drought conditions like the western corn belt. We actually do have higher water-use efficiency due to this higher CO2 in the air.”
The effect is even more pronounced in soybeans and other grains, which receive “direct fertilization” from CO2. The evidence to date suggests that 10 % to 25 % of soybean and cereal yield gains over the last 40 years are the result of higher CO2 in the air, he said.
In other good news, research shows that rainfall in North America is up slightly over the last 20 years, even in the dry U.S. midwest, he said. The last, true continental drought was in 2012, and the heat wave spikes of the 1930s and 1950s have yet to be matched.
More negatively, Schussler conceded that rainfall now comes more often in bigger deluges with a lot of wind, which can flatten corn. He suggested the development of shorter corn varieties could be the next trend to counter the lodging problem.
He confidently predicted that scientific advancement and continued crop development are up to the challenges that climate change might pose in North America. He’s involved with one initiative that resulted in more drought resistant corn hybrids using conventional plant-breeding and trait-selection techniques. Gene-insertion technology promises further advancement.
“The concept that we’ve run out of ideas to increase yield is not true,” he said, also noting an ongoing “Holy Grail” effort to boost the inherently low 1 % efficiency of plant photosynthesis as a prime example.
He declined to answer an audience question on whether there’s an actual need to cut greenhouse gas emissions, deeming it too political. “I would just say I’m very confident that we should not have starvation as our number one concern in the next 50 years,” he said.
He did place CO2 in a broader context, pointing out that levels were 7,000 ppm about 600 million years ago, compared with only 425 ppm today. “So that puts things in perspective … We’re in some of the lowest CO2 and lowest temperatures that the world has ever seen over the millennia.”
Agriculture, he also pointed out, accounts for just 10 % of global greenhouse gas emissions, much less than transportation (29 %), electricity (25 %) and industry (23 %). “So when you hear a lot of negative press about how agriculture is hurting the world due to of our intensive management, keep that in perspective. There are a lot of other things in the world that can be improved … and they are not involved in making food compared to us.”
