Nature World: Evidence of this previous warm period came from an analysis of ancient plankton fossils drilled from the ocean floor.
By studying the relationship between CO2 levels and climate change during a warmer period in Earth's history, the scientists have been able to estimate how the climate will respond to rising CO2 levels - a parameter known as "climate sensitivity." The findings, published in the journal Nature, are in line with future predictions from the Intergovernmental Panel on Climate Change...