About 12 million years ago, Earth wasn't sensitive to carbon dioxide ups and downs. But like seasonal allergies that develop when one gets older, the planet's climate has started responding to changing CO2 concentrations relatively recently, according to new findings from paleoclimate researchers.
The prevailing understanding in climate science is that there's been a persistent connection between CO2 levels and the Earth's climate: Long ago when the Earth was frozen, CO2 concentrations were low; when it was hotter, the level of CO2 was higher. Research published this week in the journal Nature just might have burst that thought bubble.
University of California Santa Cruz ocean sciences professor Ana Christina Ravelo and grad student Jonathan LaRiviere led a team of scientists in reconstructing the climate conditions during the late Miocene epoch, which was a period about 12 million years ago when the planet was warmer than it is now. To achieve this, they used cores collected from the ocean bottom by scientists aboard the research vessel JOIDES Resolution.
Deep-sea cores held microfossils of microscopic plankton that date from the Miocene, and the scientists reported that they made new stable isotopic measurements of those samples. Their analysis showed that ocean temperatures across much of the North Pacific were 9 to 14 degrees Fahrenheit warmer than they are today, while the CO2 concentration was so low it was comparable to just before the Industrial Revolution.
Comparing that with ocean temperatures and CO2 levels over the past five million years, the paleoclimate researchers demonstrated that changing climate conditions became increasingly tied to changing CO2 levels. In other words, the climate and carbon dioxide have become strongly coupled.
This study demonstrates that Earth's climate sensitivity could be at an all-time high today, Ravelo told the university. "This means that the ocean and climate systems are poised to readily respond to even small changes in carbon dioxide," she said. We're going to need more than nasal spray to deal with that.
This story was provided by Discovery News.