Why are scientists almost 100 percent sure that global warming is happening and that it is a product of human activity?

  • They know that burning fossil fuels releases extra carbon dioxide (CO2).
  • They know that CO2 is a greenhouse gas.
  • They know that greenhouse gases absorb heat rising from the earth's surface.
  • They measure that greenhouse gas levels are rising in the atmosphere.
  • They measure that the earth is getting warmer.

By putting all these things together climate scientists are almost definitely convinced that global warming is happening and that it is cause by human burning of fossil fuels.