As of Thursday, the average temperatures across the Northern Hemisphere have breached the 2 degrees Celsius mark above the mark that we consider dangerous to humanity.
As a rule of thumb ( according to Arrhenius’ equation), the rate of chemical reactions generally double with an increase of 10 degrees Celsius. So a 2 degree increase is a significant change in the environment’s behavior.
All of the carbon we dumped into the atmosphere has concentrated itself in the oceans, making them hotter and more acidic. With sea levels rise of a meter, Americans will have to abandon coastal cities and head for the Mountains. This in turn would severely strain our resources. We have ample size to hold the current population. To illustrate, with a landmass the size of Texas, every family could own on an acre of land and live comfortably. However, climate change will strain our resources to a point to make 6-7 billion people on the planet unfeasible.