New Study Reveals CO2 Doubling Could Drastically Increase Global Temperatures Beyond Current Estimates

A new study in Nature Communications reveals that a doubling of atmospheric #CO2 could increase Earth's temperature by 7 to 14 degrees, much higher than IPCC estimates, highlighting the urgent need for stronger CO2 emission reductions and technological innovations.

A recent study published in Nature Communications reveals that a doubling of atmospheric CO2 could raise Earth's average temperature by 7 to 14 degrees, significantly more than the #IPCC's estimate of 2.3 to 4.5 degrees. This finding is based on an analysis of sediments from a 45-year-old Pacific Ocean drill core, conducted by researchers at #NIOZ and the Universities of Utrecht and Bristol.

The core, which spans the past 18 million years, was chosen for its well-preserved organic matter due to oxygen-free conditions at the ocean floor. Researchers derived past seawater temperatures using the TEX86 method, which analyzes membrane substances of archaea, microorganisms that adjust their membrane chemistry based on water temperature.

To estimate ancient atmospheric CO2 levels, the team used a novel approach analyzing the chemical composition of chlorophyll and cholesterol in algae. Algae prefer the lighter carbon isotope 12C, but will use the heavier 13C more when CO2 levels are low, making the 13C content a proxy for past CO2 concentrations. The study found that CO2 levels dropped from 650 parts per million (ppm) 15 million years ago to 280 ppm before the industrial revolution.

By plotting temperature and CO2 data over the past 15 million years, researchers discovered a strong correlation between the two. Fifteen million years ago, the average temperature was over 18 degrees Celsius, 4 degrees warmer than today and comparable to the IPCC's extreme scenario for 2100. This research suggests that CO2 may have a stronger impact on temperature than currently estimated, highlighting the urgent need for measures to reduce CO2 emissions and adopt technological innovations to mitigate climate change.

Professor Jaap Sinninghe Damsté of NIOZ and Utrecht University, who supervised the study, emphasized the importance of this research in understanding future climate scenarios. The clear warning is that CO2's impact on global temperatures could be more significant than previously thought.

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Resources: Caitlyn R. Witkowski, Anna S. von der Heydt, Paul J. Valdes, Marcel T. J. van der Meer, Stefan Schouten, Jaap S. Sinninghe Damst�. Continuous sterane and phytane δ13C record reveals a substantial pCO2 decline since the mid-Miocene. Nature Communications, 2024; 15 (1) DOI: 10.1038/s41467-024-47676-9