A quick post on an interesting article in Bloomberg last week about expansion of corn in Canada. I’ve been keeping an eye out for stories about possible adaptations in the wake of this summer’s poor corn harvest in the U.S (or as Stephen Colbert called it – our shucking disaster). As we’ve discussed before on this blog, having crops migrate northward is a commonly cited adaptation response. In addition to being encouraged by the warming trends, the northward migration of corn could be helped by new varieties that have shorter cycles and better cold hardiness.
It’s certainly interesting to see the expansion of corn in areas like Alberta and Manitoba, or for that matter in North Dakota. But too often media stories, or even scientific studies, present the changes as de facto proof of adaptation. The question is not really if crops will move around – they always have moved around in the past, and will continue doing so in the future. And I don’t even think the key question is whether climate change will be an important factor in them moving around – the evidence is still slim on this question but the Canada transition is clearly one made easier by the climate trends. Instead, the most important issue is how much is gained by these adaptive moves relative to the overall impacts of climate trends.
Sol has been analyzing this in some detail for different regions around the world, so he will hopefully have some more to say with numbers to back it up. But let me just point to two relevant questions that were each alluded to in the Bloomberg article. First, is the scale of expansion large relative to the main zones of production? In the case of Canadian corn, the article mentions about 120,000 Ha of corn area sown in three provinces of Canada (Manitoba, Saskatchewan, and Alberta). That is less than one-half of one percent of the U.S. corn area.
Second, what is being displaced by the crop expansion? In most cases, including Canada’s, corn is being grown by farmers that used to grow wheat or barley. So the gain in corn production is offset to a large degree by the loss in wheat production (although not completely, since corn typically produces more grain per hectare than wheat). Modeling studies of adaptation typically assume there is a net expansion of total cropland in cold areas, not just expansion of individual crops. Without net area expansion, it is hard to offset losses incurred at lower latitudes.
There is certainly an argument to be made that big expansions of net area will only be seen with more substantial shifts in climate, since only then will it pay to make the large capital investments to open up new areas for agriculture. But it’s also possible that the constraints on expanding into new areas (poor soils, lack of infrastructure, property rights, rules on foreign investment) are large enough that only a modest amount of expansion will happen.
The main point is that changes in crop area have to be judged not just by whether or not they happen, but by whether their impact is large enough to matter. For most readers of Bloomberg, “large enough to matter” may simply mean that it’s an opportunity to make a lot of money. But for those of us interested in global food supply and price dynamics, the scale of interest is much larger. A 25% drop in U.S. corn production leaves a big hole to fill – it’s not enough to drop a few shovels full of dirt in and call it a day.