Paleothermometry Using Archaeal Lipid Biomarkers

Palaeothermometry using archaeal lipid biomarkers exploits the temperature-sensitive composition of glycerol dialkyl glycerol tetraethers (GDGTs) produced by marine and freshwater Archaea. Variations in the degree of cyclisation and hydroxylation of GDGTs, encapsulated in indices such as TEX86 and related OH-GDGT proxies, provide quantitative estimates of past sea surface and lake temperatures. Advances in calibration techniques and expanded global surface-sediment databases have strengthened the reliability of these proxies, while laboratory and culture studies have refined our understanding of archaeal lipid biosynthesis and its environmental controls. Taken together, archaeal lipid palaeothermometry affords a robust approach to reconstructing regional and global temperature changes over timescales ranging from decades to millions of years, with applications in climate model validation, palaeoceanography and assessments of rapid climate events in Earth’s history.

Research from Nature Portfolio

Recent investigations have confirmed that core-membrane GDGTs in open-ocean suspended particulate matter derive exclusively from Group I Thaumarchaeota, demonstrating that contributions from other archaeal groups do not compromise the TEX86 sea surface temperature proxy. Complementary work in a stratified Norwegian lake has shown that oxygen and redox gradients, rather than temperature alone, strongly influence GDGT distributions; integrating caldarchaeol/crenarchaeol ratios with TEX86 and the BIT index is now recommended to disentangle stratification effects and improve palaeo-temperature reconstructions in lacustrine settings.

Paleothermometry Using Archaeal Lipid Biomarkers publication trend

The graph below shows the total number of articles in paleothermometry using archaeal lipid biomarkers across all publications each year (not limited to Nature Index journals).

Technical terms

Glycerol dialkyl glycerol tetraethers (GDGTs): Membrane-spanning lipids produced by Archaea, varying in cyclopentane rings and hydroxyl groups.

TEX86: A palaeothermometer index based on the ratio of GDGTs with 86 carbon atoms, reflecting past sea surface temperatures.

OH-GDGT: Hydroxylated GDGT lipids containing one or more hydroxyl groups, used to refine temperature sensitivity in colder regions.

Caldarchaeol/crenarchaeol ratio: A lipid ratio indicating contributions from methanogenic versus ammonia-oxidising Archaea, useful for assessing stratification.

BIT index: The Branched and Isoprenoid Tetraether index, quantifying the relative input of soil-derived branched GDGTs versus marine isoprenoid GDGTs.

References

1. Evaluating isoprenoidal hydroxylated GDGT-based temperature proxies in surface sediments from the global ocean. Geochimica et Cosmochimica Acta (2024).
2. Disentangling Effects of Sea Surface Temperature and Water Depth on Hydroxylated Isoprenoid GDGTs: Insights From the Hadal Zone and Global Sediments. Geophysical Research Letters (2023).
3. A TEX86 surface sediment database and extended Bayesian calibration. Scientific Data (2015).
4. GDGT distribution in a stratified lake and implications for the application of TEX86 in paleoenvironmental reconstructions. Scientific Reports (2016).
5. Membrane Lipid Composition of the Moderately Thermophilic Ammonia-Oxidizing Archaeon “Candidatus Nitrosotenuis uzonensis” at Different Growth Temperatures. Applied and Environmental Microbiology (2019).
6. The absence of intact polar lipid-derived GDGTs in marine waters dominated by Marine Group II: Implications for lipid biosynthesis in Archaea. Scientific Reports (2020).