Researchers have revealed that today’s levels of carbon dioxide (CO2) are actually higher than they were 23 million years ago. A research team from the University of Louisiana in the United States has used fossils of ancient plant tissues to create a new record of atmospheric CO2 that spans 23 million years of uninterrupted Earth history.
They have shown elsewhere that the relative amount of carbon, carbon-12, and carbon-13, two stable isotopes, changes in response to the amount of CO2 in the atmosphere as plants grow.
The findings, published in the Journal of Geology, measure the relative amounts of these carbon isotopes in fossil plant materials and are a next-level study calculating the increased atmospheric CO2 concentration of ancient plants.
Dramatic increase in CO2
Furthermore, the study found no evidence that there are any fluctuations in CO2 that may be comparable to the dramatic CO2 increase of the present time, suggesting that today’s sudden greenhouse disruption is unique in recent geological history.
According to the researchers, since major evolutionary changes over the past 23 million years have not accompanied major changes in CO2, ecosystems and temperatures may be more sensitive to small changes in CO2 than previously thought.
For example: the adequate global warming of moderate Pliocene (five to three million years ago) and moderate Miocene (17 to 15 million years ago) was associated with only a slight increase, which is sometimes studied as a comparison of current global warming.