His theory is that enough people died that farm fields reforested and sucked up carbon dioxide establishing a kind of anti-green-house-gas effect.

After two hours' drive, we came to what is called a green house, through the glass wall of which, we saw lots of green plants.

For a start, all animals, such as cows, pigs and sheep, always gas limed methane, which is the second most common green house gas after carbon dioxide.