End of the Eemian

After the Eemian, the Ice Age. Apparently the question here is how America's Ice Age extended itself into northern Europe and the Alps.

Continent Parias is horrible for climate, as every Coloradan can tell you. As Art Bell taught me in The End of Tomorrow, Europe gets a Gulf Stream / North Atlantic Current. A coldsnap like the Maunder Minimum might freeze the odd river. But - Marcus Lofverstrom says - even a long coldsnap is difficult to account for the north joining Baffin and Alaska as Ice Supercontinent Arctica.

Lofverstrom points to ocean gateways in the Canadian Arctic Archipelago. Bell said Panama's gateway was healthy for Europe; Lofverstrom adds the Northwest Passage. As long as it's open, American ice stays here. When it blocks out, Markland's white walkers come to Scandinavia.