This map shows how much average winter temperatures have risen in the past 30 years. Much of the Midwest and Great Plains have seen a more than 7°F increase during this time span.
What we talk about when we talk about climate change
Americans have found it hard to have a rational discussion about global warming since 2006. That’s the year the documentary An Inconvenient Truth hit theaters and kick-started a conversation that has polarized our thoughts about this topic. Thanks, Al Gore.
Today, perceptions of climate change tend to leave people concerned, dismissive or uninformed. Vern Grubinger, an Extension professor with the University of Vermont, believes the conversation is important to have nonetheless.
"Some farmers, just like some of the general public, are skeptical that climate change is even real," he says. "Others are doubtful it will affect agriculture, and some don’t even want to bring it up for fear it might generate yet another concern about the environmental impact of farming. Others are already acting to prepare for it."
Dave Changnon, a climate scientist at Northern Illinois University, agrees. "The problem with climate change is it’s so political," he says. "I’ve almost given up talking about it unless the discussion is focused on the science-based aspects."
One thing is clear: Environmental shifts are already subtly affecting crop yields, increasing risks and altering farm management practices.
"The scientific evidence leaves little room for doubt that our climate is changing, and that agriculture will be affected," Grubinger says. "To me, it’s not a political issue but a practical one. Farmers should prepare to manage for changes of any type that have a reasonable chance of affecting them."
Changnon hopes to steer people away from general climate change discussions. Instead, he focuses on measurable occurrences and outcomes, such as what to do if warmer temperatures spike insect populations, or how increased water vapor could affect Midwestern weather patterns.
What’s changing? Corn "knee-high by the Fourth of July" has become laughably out of date in recent years. That’s largely because crop maturity is much further along by July 4 than crops a generation ago. Consider this: According to an Iowa State University study, from 1981 to 2005,
the Midwest saw its average corn planting date advance by 0.40 days per year and the average soybean planting date advance by 0.49 days per year.
Planting dates have slowly but surely increased at a fairly predictable pace for the past 30 years. Less predictable are what the U.S. Global Change Research Program calls "extreme weather events," which the group has tracked since 1960. These events, which shove yields beneath the trend line, occur at random intervals, although the overall incidence is up.
These trends might sound troubling, but public and private researchers alike are striving for new solutions. One good example is the recent introduction of drought-combating corn hybrids, such as DuPont Pioneer’s Optimum AQUAmax and Monsanto’s DroughtGard.
Expect big improvements across the industry in agronomic traits, says Bayer CropScience corn trait research manager Brian Vande Berg.
"Collectively, I think our understanding of plant biology has increased to the point where we can make some logical approaches into our research pipelines to try and improve yield," he says. "The use of genome sequencing and bioinformatics allows us to understand plant biology in more detail than even five years ago."
Shifting pests. With earlier planting dates, crops get a head start. Unfortunately, so do many weeds, insects and diseases that can knock down yields.
Insects are cold-blooded animals, notes Abby Seaman, vegetable IPM coordinator with the New York State Integrated Pest Management (IPM) Program at Cornell University. Their body temperature is approximately the same as their environment, and that is an important environmental factor influencing their distribution, development, survival and reproduction, she says.
One example of changing pest patterns is the corn earworm in upstate New York. A network of pheromone traps is used to monitor the flights of the major worm pests of sweet corn. When the network was started nearly 20 years ago, corn earworm, a migratory pest that is not known to overwinter in upstate New York, arrived in the area sometime between late July and late August.
"Now we are seeing a flight early in the season, either from migration or possibly from overwintering in New York, and farmers are having to apply more insecticides to manage them," Seaman says.
The current evidence shows a likelihood of more outbreaks from a wider variety of insects and pathogens, either due to overwintering in new geographies or by migrating from a shorter distance, Seaman explains. "We can’t definitively attribute this to climate change, but whatever the reason, we’re likely to see more unfamiliar pests," she says. "Farmers just need to be vigilant in scouting their fields and keeping records, and current IPM recommendations
already play well into that."
Lewis Ziska, a plant physiologist with USDA–Agricultural Research Service, offers some additional examples of how rising temperatures affect pest migration.
"The current distribution of both Japanese honeysuckle and kudzu is limited by low winter temperatures," he says. "Global warming could extend their northern limits by several hundred miles."
Ziska says he hopes research can continue so farmers are not caught unaware by possible shifting pest populations.
Whether climate change is man-made or driven by Mother Nature, whether it’s fleeting or here to stay is immaterial. If volatile times are ahead, and if unexpected pests are lurking, farmers who are versatile and adaptable will have the most success.
Continued climate change education could even lead to profitable production practices, Grubinger says.
"Many actions that address climate change are simply good management practices," he says. "For example, improved irrigation and drainage systems; efficient use of nitrogen fertilizer and manure; greater farm energy efficiency; cover cropping to add carbon to the soil; and development of local markets to reduce packaging, transportation and storage, which all use energy and create greenhouse gases."
- October 2012