Researchers used laser-based techniques to measure oxygen-17 in 15-million-year-old fossilized eggshells.
The study reveals that 15 million years ago, plants were potentially 40% less active at absorbing CO2 than today.
The Miocene Epoch serves as a critical historical model for understanding future climate change and greenhouse conditions.
The research provides deeper insights into how the global biosphere responds to elevated atmospheric carbon dioxide levels.