
Nine tiny fossil leaves of conifers and extinct seed ferns from Båga Formation, Denmark, used to reconstruct the carbon dioxide levels in the atmosphere about 183 million years ago. The fossil leaves, which were extracted from rock by washing the rocks in acids, are more resistant than rock to acid.
Photo by John Weinstein; courtesy of The Field MuseumStudying climate change is incredibly complex, yet retracing climate change and the causes behind those changes is the only way to understand the effects of burning massive amounts of fossil fuels today.
Over the course of geological time, the amount of carbon trapped in land and the oceans has waxed and waned. So has the amount of carbon dioxide in the atmosphere. These fluctuations correlate closely with changes in global temperatures. Therefore, studying the flow of carbon between land, water and atmosphere through geological ages can shed light on issues surrounding today's global warming.
New research described in the May 26 issue of Nature provides some missing pieces in the puzzle depicting the global carbon cycle over geological time. During what geologists call "oceanic anoxic events," it has long been suggested that a large amount of the greenhouse gas carbon dioxide is removed from the atmosphere by millions of microscopic organisms that dwell in the oceans. They do this by trapping carbon in their bodies. When they die, their bodies rain down to the ocean depths and are buried by sediment, locking away the trapped carbon from the atmosphere for million of years.