Earlier quoted context omitted.
Unfortunately, plants do not sequester much CO2 long term. Instead, the CO2 gets released back to the atmosphere as plants die off.
Unless you bury the plants. That's what happened to create coal and oil. The problem of too much CO2 in the atmosphere will solve itself in a few thousand years: the ocean currents will sequester lots of carbon in the depths of the sea. Of course, people alive today and their children and grand-children don't want to wait for so long.
1. http://www.realclimate.org/index.php/archives/2005/03/how-lo...
2. http://www.nature.com/climate/2008/0812/full/climate.2008.12...