Is the greenhouse effect man-made?
The natural greenhouse effect is not man-made. The
earth's carbon and water cycles keep enough greenhouse gas in the
atmosphere to warm the planet so that life can exist. This has
happened for millions of years.
The enhanced greenhouse effect is man-made. By burning
fossil fuels and by deforestation we have been adding extra
greenhouse gases to the atmosphere since the beginning of the
Industrial Age (around 1750).