Breakthrough Discovery on the Role of CO2 in Climate History
Scientists at the University of St Andrews have made groundbreaking discoveries about the Earth’s climate history, opening up new questions about the role of CO2 in future climate transitions.
For the first time, researchers at the University have unearthed a clear link between atmospheric CO2 levels and Earth's dramatic climatic shifts, spanning hundreds of millions of years. This breakthrough, detailed in Nature Geoscience, opens a window into ancient climate dynamics and underscores the enduring influence of CO2 as a climate regulator.
Carbon dioxide, the most significant greenhouse gas in Earth's atmosphere, traps heat and radiates it back to the planet, making it a key driver of modern climate change. While its contemporary role is well-documented, the historical impact of CO2 has long been enigmatic, buried within Earth's geological archives. The St Andrews team has now unlocked this "rock-locked" history, tracing how CO2 shaped the Late Palaeozoic Ice Age — a pivotal period between 335 and 265 million years ago.
This groundbreaking research was led by Dr. Hana Jurikova, Senior Researcher in the School of Earth & Environmental Sciences in collaboration with nine other prestigious universities and institutions worldwide. Using the chemical signatures in fossilised brachiopod shells —ancient marine organisms that have survived for over 500 million years — they pieced together the atmospheric conditions of a world in flux.
Brachiopod shells, preserved across geological epochs, serve as one of nature's climate recorders. By analysing their intricate chemical compositions, researchers can decode past atmospheric CO2 levels with remarkable precision. The study revealed that during the Late Palaeozoic Ice Age, atmospheric CO2 levels plummeted to unprecedented lows, coinciding with a prolonged period of global cooling and extensive ice cover. However, this equilibrium was disrupted around 294 million years ago by massive volcanic eruptions. These eruptions released vast amounts of CO2, triggering a rapid planetary warming that melted the ice and introduced a new climatic era.
In a study done last May, St Andrews researchers discovered that CO2 levels are rising approximately ten times faster than at any point in the past 50,000 years. While carbon dioxide levels used to rise by approximately 14 parts per million over 55 years, with jumps occurring roughly every 7,000 years, the same increase now occurs in just five to six years.
These discoveries highlight CO2’s role as more than a modern driver of climate change — it has been a fundamental force in Earth's climatic and biological evolution. The findings emphasise how shifts in atmospheric CO2 have dictated the planet's transition between ice ages and warmer periods, influencing the trajectory of life on Earth. It underscores the delicate balance of Earth's climate system and the outsized impact of CO2 fluctuations.
In an era of rising atmospheric CO2 due to human activity, these findings serve as a stark reminder of the potential for rapid and profound climatic shifts. As a university that has already started implementing renewable energy projects to mitigate its carbon footprint, St Andrews researchers are going further, leading the way in uncovering the historical context of climate dynamics in order to effectively prepare ourselves for future climate challenges.
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