I think the time frames for returning to pre-human levels is longer than a few thousand years [1, 2]. 1. http://www.realclimate.org/index.php/archives/2005/03/

I think the time frames for returning to pre-human levels is longer than a few thousand years [1, 2]. 1. http://www.realclimate.org/index.php/archives/2005/03/how-long-will-global-warming-last/ http://www.realclimate.org/index.php/archives/2005/03/how-lo... 2. http://www.nature.com/climate/2008/0812/full/climate.2008.122.html http://www.nature.com/climate/2008/0812/full/climate.2008.12...