What is going to happen

We have known for hundreds of years that burning coal[1] and burning oils[2] will lead to climate change.

We know that our planet is subject to Meteorite Strikes [3], Massive Volcanic eruptions [4], Coronal Mass ejections [5], Canfield Oceans[6] all leading to mass extinctions [7]

Our population is over 8 billion people [8] and the actual number of people in some level of comfort living in harmony with other species is about 1 billion people[9]

We are headed for a collapse. [10] What will that collapse be like as the worlds poulatoin drops from 8 or 9 billion to a billion or 500 million people.[11]

We know of many civilizations that have failed.[12]

When civilizations fail due to external pressures we see the following

~Mass Migrations[13]
~Breakdown of civil society[14]
~Emergence of Warlords[15]
~Civil unrest and rioting [16]
~Starvation and Cannibalism [17]

There is no reason to think that could not happen today.