Scientists can study Earth’s climate as far back as 800,000 years by drilling core samples from deep underneath the ice sheets of Greenland and Antarctica. Detailed information on air temperature and CO2 levels is trapped in these specimens. Current polar records show an intimate connection between atmospheric carbon dioxide and temperature in the natural world.
There is, however, still a degree of uncertainty about which came first—a spike in temperature or CO2.
Scientists use air trapped in the ice to determine the CO2 levels of past climates, whereas they use the ice itself to determine temperature. But because air diffuses rapidly through the ice pack, those air bubbles are younger than the ice surrounding them.
A refined system takes into account more data and shows that the age difference in Antarctic temperature and CO2 levels is less than previously thought. Parrenin says. “I think this could help to change the tone of discussions about climate change.”
More on this in the original article from Scientific American