Speleothem Geochemistry and Climate Reconstruction

Speleothems—secondary mineral deposits such as stalagmites and stalactites—provide continuous, precisely datable archives of past environmental conditions. Their growth layers capture variations in drip-water chemistry and cave atmosphere, recording shifts in temperature, rainfall and vegetation above the cave. Stable isotopes of oxygen and carbon (δ18O and δ13C) reflect changes in precipitation amount, moisture sources and soil biological activity, while trace element ratios (Mg/Ca, Sr/Ca and others) monitor processes such as prior calcite precipitation and water–rock interaction. Advances in mass spectrometry and laser-ablation techniques now permit sub-annual resolution of these proxies, revealing seasonal to millennial-scale climate dynamics. Robust chronologies are established through uranium–thorium dating and, in favourable cases, by visible or fluorescent laminae counting. Interpreting speleothem geochemistry requires careful assessment of cave ventilation, hydrological pathways and karst reservoir mixing. When integrated with isotope-enabled climate models and other palaeoclimate archives, speleothems yield insights into monsoon variability, glacial–interglacial transitions, ocean–atmosphere teleconnections and recent anthropogenic impacts. This field thus bridges geochemistry, hydrology and climate science, with global significance for understanding natural variability and forecasting future hydroclimatic change.

Research from Nature Portfolio

Recent studies have demonstrated the power of speleothem proxies to track unprecedented anthropogenic changes. Analyses of central-eastern Brazilian stalagmites reveal geochemical indicators of evaporative demand and hydrological deficit that diverge sharply from any conditions over the past seven centuries, implicating greenhouse gas forcing in sustained regional drought since the 1970s. In tropical cave sites, paired measurements of δ18O and Mg/Ca from multi-proxy stalagmite records spanning multiple glacial–interglacial cycles have confirmed that rainfall amount and prior calcite precipitation co-vary in response to orbital and monsoon forcing. These high-resolution archives place hydrological shifts in the Australasian monsoon region several millennia after global temperature rises, refining the timing of ecosystem responses to large-scale climate transitions.

Speleothem Geochemistry and Climate Reconstruction publication trend

The graph below shows the total number of articles in speleothem geochemistry and climate reconstruction across all publications each year (not limited to Nature Index journals).

Technical terms

Speleothem: A cave-formed mineral deposit, such as a stalagmite or stalactite, that grows through the precipitation of calcium carbonate from drip water.

Stable isotope ratio (δ18O, δ13C): The relative abundance of heavy to light isotopes of oxygen or carbon in carbonate, used to infer past temperature, rainfall and vegetation changes.

Trace element ratio (e.g., Mg/Ca, Sr/Ca): The proportion of minor elements to calcium in speleothem calcite, reflecting water–rock interaction, prior calcite precipitation and hydrological variations.

Prior calcite precipitation (PCP): The process by which calcite precipitates from drip water along its flow path before reaching the stalagmite surface, altering the residual solution chemistry.

Drip water: Water that percolates through soil and bedrock into a cave, supplying dissolved ions and isotopes to growing speleothems.

References

1. Modern anthropogenic drought in Central Brazil unprecedented during last 700 years. Nature Communications (2024).
2. Multi-proxy validation of glacial-interglacial rainfall variations in southwest Sulawesi. Communications Earth & Environment (2023).
3. SISALv3: a global speleothem stable isotope and trace element database. Earth System Science Data (2024).
4. Relationship of seasonal variations in drip water δ13CDIC, δ18O, and trace elements with surface and physical cave conditions of La Vallina cave, NW Spain. Hydrology and Earth System Sciences (2023).
5. Exploring soluble and colloidally transported trace elements in stalagmites: The strontium-yttrium connection. Geochimica et Cosmochimica Acta (2023).