Global analysis reveals climatic controls on the oxygen isotope composition of cave drip water.
Where this comes from
- Record sourced from PubMed, PMID 31278295.
- Also identified by DOI 10.1038/s41467-019-11027-w and PMC identifier 6611902.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The oxygen isotope composition of speleothems is a widely used proxy for past climate change. Robust use of this proxy depends on understanding the relationship between precipitation and cave drip water δ<sup>18</sup>O. Here, we present the first global analysis, based on data from 163 drip sites, from 39 caves on five continents, showing that drip water δ<sup>18</sup>O is most similar to the amount-weighted precipitation δ<sup>18</sup>O where mean annual temperature (MAT) is < 10 °C. By contrast, for seasonal climates with MAT > 10 °C and < 16 °C, drip water δ<sup>18</sup>O records the recharge-weighted δ<sup>18</sup>O. This implies that the δ<sup>18</sup>O of speleothems (formed in near isotopic equilibrium) are most likely to directly reflect meteoric precipitation in cool climates only. In warmer and drier environments, speleothems will have a seasonal bias toward the precipitation δ<sup>18</sup>O of recharge periods and, in some cases, the extent of evaporative fractionation of stored karst water.