Michel Jullian wrote:
> If you reduce
> emissions enough, nature will pump the extra CO2
> out of the atmosphere soon enough.
They are talking about 1000 years at least for natural elimination :/
More like 300 to 600 years by my calculations. See chapters 8 and 9 in my book:
Suppose the goal is to reforest 3.9 million square kilometers, an
area the size of U.S. farmland. This could be done with conventional
techniques and CF- or fission-powered desalination. A temperate
forest sequesters 1 to 10 of carbon per hectare, per year. After 30
years, when the forest matures, that comes to about 150 tons per
hectare. So the new forest would sequester 30 billion tons. Human
activity adds 6.5 billion tons per year, so the forests would reverse
the effects of 4 or 5 years of human activity.
Suppose the goal is to remove all CO2 added since the beginning of
the industrial revolution (1800). Bear in mind that releases before
1950 were much lower than now, and the whole of the 19th century was
probably less than a decade now. Anyway, as trees mature and die off,
you would cut the deadwood in both the new and old forests and bury
the wood deep underground. This would not be disruptive even with
today's technology, and it could be made far less disruptive. Assume
you do this for area about 8 million square kilometers, you would
have to repeat about 10 cycles to bury all of CO2. That would take
about 300 years.
- Jed
