What causes the magnetic poles to shift and how would that increase the temperature in North America?
I have not yet found the explanation for WHY the poles shift, but there is a great deal of info available archeo-geologically to prove that it has happened in the past, and is happening today.
The following youtube.com video contains a very fine graphic demonstrating how it has moved over the past fifty years:
Former NASA Scientist on 2016 Geomagnetic Reversal & 2 Month Period of Rapid Shift.
https://www.youtube.com/watch?v=nHew0n0BUhw
As to how that increases the temperature in North America, it is so simple an explanation as to be mind boggling. The Earth rotates on an axis, and that axis has now shifted with magnetic north now closer to the Siberian coastline rather than the northern Canadian Islands to the west of Greenland. Even the jet stream over North America has altered course.
If this is happening on the northern end of the axis, so is it happening at the southern end of the axis. Antarctica has a great deal more ice that the Arctic. Once that begins to melt the sea levels will inevitably rise. Goodbye Florida and Louisiana. California will also be affected, but not as much because it is a mountain building coastline.