The science is settled.
http://www.realclimate.org/index.php/archives/2004/12/co2-in-ice-cores/
Nobody knows, but it didn't start because of grandpa burning wood to stay alive.
http://www.realclimate.org/index.php/archives/2004/12/co2-in-ice-cores/
Nobody knows, but it didn't start because of grandpa burning wood to stay alive.