I live in southern California, where the difference between seasons is mild, and the dominant limitation on agriculture is the lack of water. (Spring is whenever it rains, not a place on the calendar.)
In my early education, as is usual, I learned the growing season is shorter in more northern latitudes. The natural deduction is to expect less effective agriculture, further north.
Recently, I spent a week in early April in Vancouver (Canada). The weather was very (very!) nice, much warmer than I expected, and the hours of daylight longer. On reflection, all this was obvious ... but I was surprised at the time.
Northern latitudes may have shorter growing seasons, but the hours of daylight during that season are much(!) longer. What is the potential agricultural productivity of more northern latitudes?
Much of the past century of agricultural research was centered on the American mid-west. How much is possible if we further optimize agriculture for more northern latitudes, and higher levels of technology?
As the Earth warms, large expenses of Russia and Canada will thaw. Seedlings started early in artificially warmed and lit greenhouses could jump-start crops. (Or transported from more southern latitudes.) If we took full advantage of the longer hours of daylight in northern growing seasons ... what is the limit to agriculture?
With global warming, could Canada and Russia become the bread-basket of the world? Can agriculture as a technology be adapted to more northern latitudes, and take best advantage of a shorter season with longer daylight?
(In imagination, I see seedlings started in greenhouses, and robot-planters placing seedlings in just-warm fields, to capture every hour and day of longer sunlight.)
Do we know how to best take advantage of long northern days for agriculture?