Is Global Warming caused by human activities?

Obviously Yes! The increase of level of Carbon dioxide, which is one of the main Greenhouse gasses, is nothing but due to unplanned burning of fossil fuel due to industrialization and modern society. Reduction of forest lands to suffice the need of increased population is another cause of increase of Carbon dioxide.

Again, first 6 miles of Earth's atmosphere is very crucial of Earth's climate and we are heavily responsible to disturb the balance of this crucial part of atmosphere.