How does the Greenhouse Gas CO2 fit into the Global Warming Story?
The following graph shows a summary of CO2 concentrations and global temperature since the appearance of fossilized life on Earth nearly 600 million years ago. The plot clearly shows that temperatures (blue line) today are about as low as they have ever been (12 degrees C), and also that CO2 levels (black line) are about as low as they have ever been. Analysis of ancient atmosphere gas bubbles trapped in permanent South Pole ice caps covering the past 400,000 years (see graph below) shows that the levels of greenhouse gases have changed through time almost in synch with global temperature. As you look at this graph, notice the strong 100,000 year cyclicity of the temperature and greenhouse gas pattern across a time span of more than 400 thousand years. Please note that today’s date is located on the right side of this graph (0 years ago).
