The world's leading climate scientists have issued six assessments of the state of climate-change knowledge since 1990. The first five were influential, driving efforts to build global climate agreements. The sixth report, issued four days after Russia's invasion of Ukraine, has been largely overlooked.
That's unfortunate. The new report of the International Panel on Climate Change sketches out the present and future of a changing globe. Among the most profound effect of global warming will be the impact on food production. According to the IPCC, climate change has reduced agricultural productivity by 12.5% since 1961. North America, long one of the world's most productive agricultural regions, already feels the pain. The agony of Ukraine, another key grain producer, just hurts more.
Jeffrey Dukes is an ecologist who directs the Purdue Climate Change Research Center at Purdue University. In recent years, he's led the Indiana Climate Change Impacts Assessment. He contributed to sections of the sixth IPCC report related to North America and its agricultural products. I recently reached him by phone at his office in West Lafayette, Indiana. Here is a transcript of our conversation, edited for length and clarity.
Adam Minter: The new IPCC report predicts with “high confidence” that climate change will shift the ranges of North American agricultural production. Is it as simple as, corn moves north to Canada?
Jeffrey Dukes: It's more complex than that. We can expect that corn will be grown further north. Crops will be in Canada, and they'll be growing more and different crops than they do currently. It also means that in a given location a crop will become more or less productive. In a given place, you may see the yield of some crops go up due to climate change, and for some crops the yield may go down. Probably in both cases the yields will be more variable year to year.
Carbon dioxide concentrations are rising, which give plants the potential to grow faster when conditions are good. So you may get a good weather year, reasonably often at first, maybe less often further into the future. And with that increased CO2 concentration you may get fantastic yields. But then you may get more frequent years when you have really low precipitation, and if you don't have irrigated crops, you're seeing really low yields.
Then some crops being grown at the edge of their ideal regions right now may just start disappearing from those regions.
AM: One of the misconceptions that many people have is that climate change will be all about drought, as we've recently seen in the American West and Southwest. But some places — such as Iowa — are actually going to become wetter. What's the impact of that?
JD: Much of the Upper Midwest is facing wetter conditions overall, especially in winter and spring. Unfortunately, projections don't suggest we're necessarily going to be much wetter in the times of year when we need the precipitation, which is summer and fall, when crops are really growing.
Having wetter conditions isn't so great if they happen in the winter and spring, because that affects when farmers can get into the fields. If the soils are too wet, you can't get your farm machinery in, you can't plant, especially in the flatter regions. So those wetter conditions are potentially shrinking your growing season.
In the summer and fall, we don't expect it necessarily to be much wetter. But we do expect it to be warmer. So the demand for water from the crops will actually go up. That will lead to drier soils, and more instances of drought and yield losses to dry soils than we have now.
AM: Those won't be the only challenges.
JD: We expect more weed and pest species are going to be able to survive in a given location. So farmers are going to have broader suites of challenges to managing pests. So that's absolutely a challenge.
For people farming perennial crops, like fruit trees, they'll need to be concerned with the chilling hours. A lot of the fruit crops need a set time when it's cold, but not too cold, to really sort of maximize their flowering and subsequent fruit set. And so if they don't get those chilling hours anymore, because essentially the warmer conditions have extended into what used to be their chilling hours, then they could see yields decline.
AM: What about wheat? We're hearing a lot about wheat shortages due to the war in the Ukraine. Is it going to become harder for American farmers?
JD: Wheat is a plant that could benefit from the increase in CO2 concentrations and it should be able to grow in more places in Canada in the future. Right now I think its extent in the US is really limited by economic factors, not growing conditions. If wheat became the economical choice to grow, sure, we could see a big expansion of it. We used to grow a lot more wheat here in Indiana than we do now. That didn't have anything to do with the shift in climate. I think, as a nation, we're well poised to grow a lot of wheat now and into the future if it turns out that that's the profitable thing for farmers to do.
AM: Are there ways to adapt beyond changing crop mixes?
JD: I think good forms of adaptation for climate change in North American regions require thinking about how to get maximum yields while growing cover crops [crops that cover and protect the soil instead of leaving it bare] and abandoning the concept of tillage. The farmers who are capable of keeping a live plant on the ground for the majority of the growing season are going to do their future selves a lot of good by retaining the soils that they have. The soils will be better able to hold onto moisture, better able to let moisture infiltrate. Those wetter springs are going to be less consequential, and the soils will hold more water into the growing season and fall. The abundance of soil fauna, earthworms and other things that will be growing there, will create a soil structure that's going to be super helpful to farmers going forward.
AM: What is the argument for preserving biodiversity and ecosystems as a means of protecting agriculture in an era of climate change?
JD: There are tons of different answers to that question, but for one thing, our agriculture species were all uncultivated species before, and they all have wild relatives. With these changing climatic conditions, and the changing mix of pests and diseases, we need all the genetic tools that we can have at our disposal.
There are other aspects that have to do with things like native pollinators. In many parts of the world, the native insects are responsible for a large fraction of the pollination of our crops. Pollinators don’t live in intensely farmed agricultural areas, they live in more natural areas, so we need to protect some of these natural areas.
AM: I'd like to ask you to prognosticate a bit. In North America, will it become harder to grow the food that consumers want in coming years and decades?
JD: I think that growing food in North America over the coming years and decades can be just about as straightforward as it is now with the improving technology that we have — if we minimize the rate of climate change. But if we let climate change continue unchecked, then it’s certainly going to become much more difficult.
Some of this battle/opportunity for minimizing climate change is playing out in the heart of the Midwestern agricultural landscape. These lands that we are growing crops on, they can double as energy factories based on wind production or based on conversion to solar farms. Solar farms can be pollinator habitats, they can help neighboring farms grow pollinator-dependent crops.
There’s a vision for a different, highly productive Midwestern agriculture that is providing energy not through ethanol, but rather through solar and wind. And simultaneously providing more food around the world than it does today. I don’t think that necessarily has to be harder. I don’t think this is a doom-and-gloom scenario. This could actually be more profitable and better for the planet.
Bloomberg
