A doubling of CO2 would increase global temperatures by up to 14 degrees

Analysis of sediments from the Pacific Ocean near California, conducted by researchers at NIOZ, Utrecht and Bristol University, indicates that CO doubles.₂ The atmosphere will lead to an increase in the Earth’s average temperature up to 14 degrees.

„The temperature rise we found is 2.3 to 4.5 degrees higher than previously estimated by the UN climate panel, the IPCC.”said first author Caitlin Witkowski.

The researchers used a 45-year-old drill core retrieved from the depths of the Pacific Ocean for the study. „I realized that this core is very attractive to researchers because the ocean floor at that location has had oxygen-free conditions for millions of years.” Professor Jab Sinning Damsday, senior scientist at NIOZ and professor of organic geochemistry at Utrecht University, said:

„As a result, organic matter is not broken down as quickly by microbes, and more carbon is preserved.” said Tamsday. He was also Witkowski’s supervisor, whose doctoral thesis included this research.

“CO₂ It has not been studied from the same place in the last 15 million years. Witkowski said.

The top thousand meters of drill core represents the last 18 million years. With these data, researchers can trace past ocean water temperatures and ancient atmospheric CO₂ levels using a new approach.

The temperature was determined using the TEX86 method, which was developed by researchers at NIOZ 20 years ago. „The method uses specific substances found in the membranes of archaea, a distinct class of microbes.” Domsday explains.

„Those archaea evolved the chemical composition of their membranes depending on the temperature of the water in the upper 200 meters of the ocean. Materials from those membranes were found as molecular fossils in ocean sediments and are still being analyzed today.

Scientists have devised a new method to estimate atmospheric CO₂ levels by analyzing the chemical makeup of two specific compounds commonly present in algae: chlorophyll and cholesterol. This represents the first instance of using cholesterol to measure CO₂ stages and the first instance of using chlorophyll for this particular period. Algae must absorb CO₂ It converts water from water through photosynthesis to form these compounds.

„A very small fraction of Earth’s carbon occurs in 'heavy form.’ ¹³C instead of usual ¹²C. has a clear preference for algae ¹²C. However, low CO₂ Concentrated in water, more algae are rarely used ¹³C. Thus, the ¹³The C content of these two materials is a measure of CO₂ content of sea water. And it is, according to solubility laws, related to CO₂ Content of the Atmosphere” says Tamsday.

With this innovative approach, the concentration of CO is seen₂ It has dropped from 650 parts per million 15 million years ago to 280 just before the Industrial Revolution.

When scientists map recorded temperatures and atmospheric CO₂ Relative positions from the last 15 million years, they show a significant correlation. Average temperatures exceeded 18 degrees 15 million years ago, which is 4 degrees higher than current temperatures and the IPCC’s forecast for 2100 is in line with the UN Climate Group’s most extreme scenario.

„So this research gives us a glimpse of what the future might look like if we take very little action to reduce CO.₂ It also implements certain technological innovations to offset emissions and emissions” Women said. „A clear caveat of this research: CO₂ Concentration may have a stronger effect on temperature than we currently take into account!

Journal Note:

1. Caitlin R. Witkowski, Anna S. Van der Heide, Paul J. Valdez, Marcel DJ. Van der Meer, Stephen Schouten & Job S. Sinning Tamesday. Continuous sterane and butane δ¹³The C log exhibits significant pCO₂ Decline since the middle of the Miocene. Nature Communications, 2024; DOI: 10.1038/s41467-024-47676-9