The Chicken or the Egg: CO₂ and Temperature
The other day, I had a rather civil discussion with a climate change denier. His main argument was that, since the carbon dioxide (CO₂) concentration has historically followed the Earth’s temperature trend, it could not possibly be that man-made CO₂ emissions now dictate our natural climate.
After all, he went on, if CO₂ were responsible for a runaway climate effect, then we would have surely seen such effect during hotter periods in climate history.
When I presented to him science-based counterarguments, he basically ignored them and continued with his narrative. Why people might dismiss climate science, is food for thought for another article.
The conversation with my climate skeptical fellow human being inspired me to descend deeper into the lion’s den. Let us see how far I get. If we are lucky, we might actually find out whether it was indeed the chicken or the egg.
Deep into the Past
First things first: Does atmospheric CO₂ historically lag the Earth’s temperature?
Based on ice core data from the Vostok Station in Antarctica, Georgios Florides and Paul Christodoulides (see section 2.4) provide a positive answer to our question: During the last three glacial-interglacial transitions over the past 420,000 years, an elevation in…
