What are two theories that scientists believe are the reasons for the increases in temperature

1)Climate change is happening. It's caused primarily by the burning of oil, gas, and coal.

2) Evidence for global warming !! Most scientists agree that the Earth's climate is getting warmer. This is called global warming. Most, but not all, scientists believe that the cause of this is an increased amount of carbon dioxide in the atmosphere due to human activities.

answer; i believe that the correct answer is (the explosion of a nearby star(supernova);