Doesn't this raise the chick and egg paradox? Is the temperature rising because CO2 is rising or is CO2 rising because the temperature is rising?
ScienceDaily — Why did the atmosphere contain so little carbon dioxide (CO2) during the last Ice Age 20,000 years ago? Why did it rise when Earth's climate became warmer? Processes in the ocean are responsible for this, says a new study based on newly developed isotope measurements.
This study has now been published in the scientific journal Science by scientists from the Universities of Bern and Grenoble and the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association.
Around 20,000 years ago, the atmospheric CO2 concentration during the last Ice Age was distinctly lower than in the following warm period. Measurements from Antarctic ice cores showed this already two decades ago. An international team of glaciologists thereafter looked even further back in time. The climate researchers found that this close connection between carbon dioxide and temperature has existed over the past 800,000 years: with low CO2 concentrations during the Ice Ages and higher CO2 values during warm periods. Now they tried to answer also the question as to where the carbon dioxide was hidden during the Ice Ages and how it got back into the atmosphere at their ends.
"We have now been able to identify processes in the ocean which are connected to the observed rise in CO2," says Dr. Jochen Schmitt, lead author of the recently published study and researcher at the Oeschger Centre for Climate Change Research at the University of Bern. According to Schmitt, during the Ice Age more and more carbon dioxide accumulated in the deep ocean, causing the concentration of atmospheric CO2 to drop. Only at the end of the Ice Age this stored CO2 was transported back to the sea surface through changing ocean circulation and thus emitted back into the atmosphere, write the scientists in the scientific journal "Science."