Between now and 2050 2 to 3 Billion people are going to Migrate north to survive

We are already seeing this in the U.S. as Central America is already becoming uninhabitable for many different reasons already. Gangs are replacing useful governments and just to survive people are moving north so they are not enslaved or killed by Gangs. Crops cannot be counted on in Central America because of floods and droughts. Governments there cannot be counted on because of Gang warfare with governments not strong enough to fight back usefully against these gangs. So, by ones and twos and 5s and 10s people are migrating north to the U.S. and Canada in order to have ANY CHANCE AT ALL to SURVIVE! 

So, places like Canada and Russia and specifically places like Siberia are going to be the new Meccas for people to get to as the climate gets more and more inhospitable nearer to the equator worldwide. And the very poorest people will be the ones who have to migrate or die where they stand worldwide too. And they will walk or ride on trains or hitch hike or take buses or drive bicycles or cars or trucks just to get to the American and Canadian Borders.

I expect up to 1 billion people just to be coming north from Central And South America up into the U.S. and Canada alone between now and 2050 to have any chance at all at survival and seeing their kids grow up alive!

NOTE: 

On a more realistic level I just checked to find out that there are just over 1 billion people in total in North, South and Central America. So, saying 1 billion people will migrate likely is an overestimation.

However, this also could mean that 200 to 300 million people might migrate north from Mexico, Central and South America into the U.S. and Canada as well. And this might be a realistic estimate of how many people come here from Central and South America to the U.S. and Canada!

First you have to realize how many children and grandchildren will be born between between now and 2050 in Mexico, Central And South America and how many of these people of all ages will out of complete desperation move north so they won't die or be enslaved in one way or another by Gangs in their native countries south of the U.S.