Lastly, whatever may be the cause, our globe will become cold some day, but this cold will only operate gradually.

What will happen, then?
The temperate zones, at a more or less distant period, will not be more habitable than the polar regions now are.

Then the population of men, as well as the animals, will flow towards the latitudes which are more directly under the solar influence.

An immense emigration will take place.

Europe, Central Asia, North America, will gradually be abandoned, as well as Australasia and the lower parts of South America.