Related Experiment Video
Updated: Feb 15, 2026

Sampling and Pretreatment of Tooth Enamel Carbonate for Stable Carbon and Oxygen Isotope Analysis
Published on: August 15, 2018
Atmospheric CO2 effect on stable carbon isotope composition of terrestrial fossil archives
Vincent J Hare1,2, Emma Loftus3,4, Amy Jeffrey3
1Research Laboratory for Archaeology and the History of Art, School of Archaeology, University of Oxford, 1 South Parks Road, Oxford, OX1 3TG, UK. vincent.john.hare@gmail.com.
Abstract:
The 13C/12C ratio of C3 plant matter is thought to be controlled by the isotopic composition of atmospheric CO2 and stomatal response to environmental conditions, particularly mean annual precipitation (MAP). The effect of CO2 concentration on 13C/12C ratios is currently debated, yet crucial to reconstructing ancient environments and quantifying the carbon cycle. Here we compare high-resolution ice core measurements of atmospheric CO2 with fossil plant and faunal isotope records. We show the effect of pCO2 during the last deglaciation is stronger for gymnosperms (-1.4 ± 1.2‰) than angiosperms/fauna (-0.5 ± 1.5‰), while the contributions from changing MAP are -0.3 ± 0.6‰ and -0.4 ± 0.4‰, respectively. Previous studies have assumed that plant 13C/12C ratios are mostly determined by MAP, an assumption which is sometimes incorrect in geological time. Atmospheric effects must be taken into account when interpreting terrestrial stable carbon isotopes, with important implications for past environments and climates, and understanding plant responses to climate change.
Related Concept Videos
The Fossil Record
Archival Research
Elements: Chemical Symbols and Isotopes
Some symbols are derived from the common English name of the element; others are abbreviations of the name in another language — Latin, Greek or German. For example, the symbol for aluminum (common name)...
The Carbon Cycle
Isotopes
An element's atomic mass, or weight,...
Classifying Matter by Composition
According to its composition, the matter can be classified into two broad categories — pure substances and mixtures.
A pure substance is a form of matter that has a constant composition throughout with uniform properties. For example, any sample of sucrose has the same composition and same physical properties, such as melting point, color, and sweetness, regardless of the source from which it is isolated.
A mixture is composed of two or...

