Question

Atmospheric carbon dioxide concentrations increased by approximately what percent in the 20th century?

1) 1
2) 10
3) 33
4) 50

Answer 1

The atmospheric carbon dioxide concentrations increased by approximately 45% in the 20th century due to human activities, primarily the burning of fossil fuels.

Step-by-step explanation:

The atmospheric carbon dioxide concentrations increased by approximately 45% in the 20th century. In the 18th century, the concentration was around 280 parts per million (ppm), and by 2018, it had reached 408 ppm. This increase is primarily due to human activities, particularly the burning of fossil fuels.