No matter your personal opinion on the subject, talk of climate change usually conjures up images of warming, floods and rising sea levels. Those are the ecological changes predicted from coast to coast.
In the Midwest, the few degrees of warming has actually benefited agriculture, on average. But in California - where they grow more than 200 crops, including perennials such as walnuts and apricots - some crops could be adversely affected. Plus, California farmers also have new climate change regulations to contend with, which worry many growers more than the weather.
Kathleen Masterson, Harvest Public Media
Walnut farmer Russ Lester is concerned about the effects climate change could bring to his California farm.
To produce a robust walnut crop, you need the right weather, according to California walnut grower Russ Lester, whose family has been farming in the state since the 1860s. He is concerned about how the rising temperatures could affect his walnut crops.
Climate change predictions in his neck of the woods show 1 to 2 degrees of warming. And much of that warming is happening in the winter. That could be a problem.
"Walnuts actually do need a certain amount of what we call chilling hours," Lester said.
He's referring to the thousand or so hours of temperatures below 45 degrees that the trees need for winter dormancy. The cold weather actually triggers the plant to bloom vigorously in the spring. Unlike with some trees, in walnuts, the male and female flowers are separate, so having the blooms all open at once is vital.
"If we don't have it overlapping during the right time period, then the pollen won't pollinate the female flower or floret," Lester said. "That's why the chill is important, that's the trigger. If we don't get adequate chilling, what happens is then you get this staggered bloom."
Chill hours are a real concern for walnuts and almonds, some fruit trees like apricots and even for wine grapes, which are grown in various parts of California. Not only that, Lester said that he's concerned about what he calls "weather weirdness" he's been observing. For example, Lester said last year there was a freak frost in early June, which is a good month-and-a-half later than the region has had frosts in many years. Many of his walnut buds were damaged and Lester had lower yields.
As Lester indicated, warmer winters aren't the only concern climate change could bring to the region. Plant and environmental scientist Louise Jackson of the University of California Davis said models also predict higher levels of carbon dioxide in the air. The combined effect of all these possible changes is unclear.
"Mean temperature increases might be easier to cope with than with extreme events," Jackson said. "Heat waves and heat waves at elevated carbon dioxide levels are kind of an unknown."
But climate scientists aren't just focusing on temperatures.
"Another issue that we really have to face in California is drought, whether or not we're dealing with gradual drought or a combination of drought plus heat wave," Jackson said. "So there are a lot of unknowns."
Most farmers in California irrigate their crops, but there is concern that warming and less snow would reduce the snowpack in the Sierra Nevada mountains. That would mean less melt to replenish reservoirs.
Fears bigger than the weather
Scientists are probing for more information. But the question is: are farmers worried about these climate change predictions?
"All the predictions about what the future climate change is going to do to agriculture are just that -predictions, at this point," said farmer Bruce Rominger. "I'm one that believes we have affected the climate and it is getting warmer, but I'm not sure what the effects will be on my operation, so I'm not doing things right now in anticipation of this. I mean there's so much natural variation in weather here."
Romginer farms about 5,000 acres with his brother, Rick, in Yolo County near Davis. They don't like to put all of their eggs in one basket, so they grow processing tomatoes, rice, wheat, alfalfa, corn, sunflowers, safflower, wine grapes, seed onions and they're even starting to raise sheep.
Like many farmers in California, Rominger already made changes to improve water efficiency: he has installed underground tubes with drip irrigation in many of his fields. That can greatly reduce both water use and fertilizer use, because it sends the water and nutrients right where they're needed.
Still, that was an economic decision.
"The reality is farmers follow the markets," Rominger said. "We look at annual profit loss, that's what drives us."
Starting this year, businesses in California with high emissions can be charged for their contributions to greenhouse gases. The new law, passed as AB 32, is similar to cap and trade legislation that failed at the national level. This kind of system taxes polluters who emit greenhouse gases and pays industries that suck up carbon dioxide, like forests.
The law definitely affects dairies, where manure emits greenhouses gases, and many food processing plants, like tomato canning factories, will likely be taxed.
"They burn lot of natural gas to evaporate off a lot of water that comes in tomato, to make it into paste, or salsa, or ketchup, so they're going to have significant costs under AB 32 when comes into effect for ag processors," Rominger said.
If high operating costs drive out tomato plants to other states - or drive down the price plants can pay farmers - it won't be worth it for many California farmers to grow tomatoes. It'll be cheaper for food companies to buy processing tomatoes from China and elsewhere. (It won't necessarily affect eating tomatoes. Most farmers that grow tomatoes for eating are in Florida.)
Right now, California farmers aren't so much worried about the warming weather, as they are the political winds of legislators and the regulations they pass.
A silver lining?
The new law could have some positives. If farmers can show that adopting certain practices help reduce greenhouse gases, they could get paid for it.
Take farmer Tony Turkovich, a Central Valley farmer who uses drip irrigation and cover crops to reduce both his water and fuel uses. Instead of spreading nitrogen-based fertilizer, he puts the fertilizer directly into the water, which is dripped onto the plants' roots via the underground irrigation tubes.
"It's spoon-feeding the plants," Turkovich said. "And the result has been, in the last two years of the university study of measuring emissions , that we've had 60 percent less nitrous oxide emissions from our drip fields versus conventional furrow irrigation. That's huge. Really huge."
With this method, Turkovich is reducing nitrous oxide, a greenhouse gas, and he saves money while still getting a great crop yield.
The project is still in the research phase and is a far cry from having definitive data that would help it count under the cap and trade system.
The reality for farmers is that with all these economic ramifications from climate change legislation, they're far more focused on their market futures than the future of the weather.