'Reforestation on a Grand Scale'

In 1987 Carl Sagan delivered this warning about global warming on his PBS show 'Cosmos.'

He told us there were four things we can do to avert climate catastrophe:

1. Better fossil fuel efficiency

2. Renewable energy, particularly solar power

3. "Reforestation on a grand scale"

4. Alleviating poverty


Of the four, reforestation on a grand scale continues to be ignored, although it is perhaps the most important of all (as it is the only thing that can remove carbon dioxide from the air).

Scientists and ecologists have been trying to tell us for at least 30 years that if we plant enough trees - about one trillion - we could reverse global warming within a few decades.

So how stupid are we being?