Recent studies have shown that doubling the level of CO2 in the atmosphere could lead to a significantly higher rise in global temperatures than previously estimated.
This finding comes from an analysis of sediments from the Pacific Ocean near California by scientists from the US NIOZ Royal Netherlands Institute for Marine Research and the universities of Utrecht and Bristol.
Significant insights from the analysis of ocean sediments
A 45-year-old man participated in the research drill core from the Pacific Ocean, revealing insights into Earth’s climate over the past 18 million years. Preserved in oxygen-free conditions for millions of years, this drill core provided a rich source of organic material. The study found that doubling atmospheric CO2 can result in an average increase in temperature on Earth ranging from 7 to 14 degrees Celsius.
This is significantly higher than the 2.3 to 4.5 degrees predicted by the Intergovernmental Panel on Climate Change (IPCC). Caitlyn Witkowskilead author of the study, emphasized the significance of these findings: “The temperature increase we found is much larger than the 2.3 to 4.5 degrees previously estimated by the UN’s climate panel, the IPCC.”
The preserved core allowed the researchers to analyze the ancient organic matter, which according to the professor Jaap Sinninghe Damste, senior scientist at NIOZ, “offers a unique insight into past climate conditions.” The long-term anoxic state of the ocean floor slowed the decomposition of organic material, allowing the preservation of carbon compounds that provide insight into historical atmospheric conditions. This analysis represents an important step in understanding the long-term sensitivity of the climate to CO2.
Methodology: Combination of TEX86 and new approaches
The researchers used TEX86 method to estimate past sea temperatures. This method uses specific substances present in the membranes of archaea, microorganisms that adjust their membrane composition based on water temperature. These molecular fossils found in oceanic sediments provided crucial temperature data. This method, developed 20 years ago at NIOZ, is based on the analysis of chemical signatures left by archaeawhich are particularly durable and informative due to their long-term preservation in sediment layers.
Estimate the past atmospheric CO2 levels, the team developed a new approach involving the analysis of chlorophyll and cholesterol found in algae. The chemical composition of these compounds changes with the concentration of CO2 in the water and correlates with atmospheric CO2 levels. Damsté further stated: “A very small fraction of the carbon on Earth occurs in the ‘heavy form’ of 13C instead of the usual 12C. Algae clearly prefer 12C.
However, the lower the concentration of CO2 in the water, the more the algae will use even the rare 13C. The 13C content of these two substances is therefore a CO2 measurement ocean water content.” This innovative method provided a more accurate historical record of CO2 levels, showing a decline from about 650 parts per million 15 million years ago to about 280 parts per million just before the Industrial Revolution.
Unprecedented levels of CO2: Historical insights and future climate implications
The results of the study indicate that the relationship between CO2 levels and global warming is stronger than previously thought. Using a graph of inferred temperatures and atmospheric CO2 levels over the past 15 million years, the researchers observed a significant correlation. The average temperature 15 million years ago was over 18 degrees Celsius, which is 4 degrees warmer than today and similar to the extreme scenarios predicted by the IPCC for 2100. This historical perspective suggests that future climate conditions could be more extreme, CO2 levels continue to rise uncontrollably.
Damsté emphasized the implications of these findings: “So this research gives us a glimpse of what the future might bring if we take too little action to reduce CO2 emissions and also implement several technological innovations to offset emissions. A clear warning from this research is that CO2 concentration is likely to have a stronger impact on temperature than we currently consider.” The study underscores the potential for more severe climate impacts than currently expected and highlights the urgency for greater climate action and innovation .solutions to reduce CO2 emissions.
The methodology and findings of this study offer a critical reassessment of climate models and projections. By providing a more detailed and extended historical climate record, the research challenges existing assumptions and highlights the need for revised climate sensitivity parameters in predictive models. This insight is essential for policymakers and scientists working to develop effective strategies to combat global warming and its associated impacts on the planet’s ecosystems and human societies.