By Matt Owens August 2, 2014
Here's a new set of graphs I've put together. They show the past 800,000 years of the Antarctic air temperature record (from deuterium in ice cores), along with: CO2, CH4, and the amount of summer sunlight in the Northern Hemisphere.
Summer sunlight in the Northern Hemisphere has been one of the primary drivers of the ice age cycles. Carbon dioxide (CO2) has been a modulator of temperature, both directly, and likely indirectly through plant-land-climate feedbacks.