Yes, the climate in Russia, Canada and Northern Europe will be more suitable for crops, but their soil won't be. Canada's topsoil in the places you are talking about have been scraped away by glaciation, meaning they are next to useless for growing crops. Russia's permafrost will release massive amounts of methane when they melt, exacerbating the problem. Oceans will rise, swamping trillions of dollars' worth of city property (including many capital cities, and New York, for example). If you think it's not a big deal to have tens of millions of refugees, then you might need to re-evaluate your definition of "big deal", as that will cause untold pressure on infrastructure.
I guess if you don't actually look into what you claim, it all sounds peachy. It's once you actually do, and realise you are painting a rosy future not based on any actual science, do we realise we're in for quite a bumpy ride, to put it lightly. But you've already made up your mind, so this will fall on deaf ears.
The use of money is all the advantage there is to having money. -- B. Franklin