In recent years, scientists have made sizable gains in what was once
considered an impossible art — reconstructing the history of Earth’s atmosphere
back into the dim past. They can now peer across more than a half billion years.
The scientists have learned about the changing makeup of the vanished gases by
teasing subtle clues from fossilized soils, plants and sea creatures. They have
also gained insights from computer models that predict how phenomena like
eroding rocks and erupting volcanoes have altered the planet’s evolving air.
“It’s getting a lot more attention,” Michael C. MacCracken, chief scientist of
the Climate Institute, a research group in Washington, said of the growing
field.
For the first time, the Intergovernmental Panel on Climate Change, a United
Nations group that analyzes global warming, plans to include a chapter on the
reconstructions in its latest report, due early next year.
The discoveries ...