Don't you mean "appropriate"? If global climate is heating up, people will naturally move northwards in Canada and Siberia to take advantage of newly fertile farmland and moderate temps.
> people will naturally move northwards in Canada and Siberia to take advantage of newly fertile farmland
Is this the early 1900's? Farming these days doesn't require a large population - the day of family farms are few and far between. You need comparatively few people to farm an extraordinarily large area of land, so I can't see a reason why people would want to all move there for an industry they largely won't take part in.
I also doubt the moderate temperatures bit - while the average temperature will go up it will be subject to all sorts of radical weather, made more extreme by the atmospheres additional energy, and without the oceans to try and mitigate the temperature. I'm sure there will still be cold winters - moving the dial up an average of 5 C still sees the average January Fort McMurray day with a high of -5 C and a low of -17 C.
That too - people think of the oil being in the "north", but it's not, if you look at the map, it's only a 3rd of the way north of the US/Canada border.
