Climate change may make northerly areas suitable for farming. Well, sort of. They seem to have overlooked the fact that most of that territory has rather thin and poor soil, also frequently full of rocks. We could turn it into fertile farmland, but that would require composting lots of scraps to make humus. Most people can't even be arsed to do that on current farmland anymore. So don't imagine that it's going to come anywhere near what we're losing.
Then again, they also didn't consider anything beyond field crops. Land that does badly for those can do brilliantly for food forests.