Swagman wrote on May 1
st, 2013 at 11:29am:
Quote:The last time CO2 levels were so high was probably in the Pliocene epoch, between 3.2m and 5m years ago, when Earth's climate was much warmer than today.

Soooooo if it was
much warmer than today in the Pliocene and we have the same level of CO2 concentration today, then what caused the temperatures to be much warmer than today in the Pliocence?
The article actually says
Quote:The last time CO2 levels were so high was probably in the Pliocene epoch
It never said that CO2 levels today are
exactly the same as the Pliocene epoch.
Having said that, CO2 isn't the only thing that affects climate. There are changes to the earths orbit, changes in continental drift, changes in the suns heat, changes in the oceans currents. All these things have caused natural changes to the Earths climate in the past.
However if all those other factors are stable, which they have been for the past 200 years, then clearly the
current global warming we are experiencing is due to the measurable increase in the concentration of CO2.