What's a few hundred years between friends? ;-) How long would it take by harvesting algae on a large scale then?
Michel ----- Original Message ----- From: "Jed Rothwell" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Friday, February 16, 2007 6:27 PM Subject: Re: [Vo]: Re: The $25 Million Branson Climate Prize > 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 >
