The ‘greenhouse effect’ refers to the __________.
A Building up of pollution in the atmosphere
B Gradual warming of the Earth’s atmosphere
C Hole in the ozone layer
D Increase in human population on Earth
The ‘greenhouse effect’ refers to the __________.
A Building up of pollution in the atmosphere
B Gradual warming of the Earth’s atmosphere
C Hole in the ozone layer
D Increase in human population on Earth