How do we know that levels of CO2 don just increase as temperature increases?
Over the last several hundred thousand years the temperature has varied mainly due to changes in the Earth’s orbit around the sun. Over this period changes in temperature did drive the levels of CO2 in the atmosphere. However, now the levels of CO2 are much higher and increasing much faster than at any time over the last 650 thousand years – meaning what is happening now is very different to anything that has happened over the last 650 thousand years.
