On Wednesday, October 9, 2013 11:50:44 AM UTC+13, dennis@home wrote:
On 08/10/2013 21:08, Roger Chapman wrote:
The greenhouse effect makes a negligible difference in
greenhouses.
So why have a greenhouse if they don't work?

Some people put lots of extra CO2 in their greenhouses to make their plants grow faster, because there's not enough CO2 in the air at the moment. Plants and other organisms keep using it up and forming huge deposits of soil and limestone etc.