Global analysis reveals climatic controls on the oxygen isotope composition of cave drip water

Baker, Andy; Hartmann, Andreas; Duan, Wuhui; Hankin, Stuart; Comas-Bru, Laia; Cuthbert, Mark O.; Treble, Pauline C.; Banner, Jay L.; Genty, Dominique; Baldini, Lisa M.; Bartolomé, Miguel; Moreno, Ana; Pérez‐Mejías, Carlos; Werner, Martin

doi:10.1038/s41467-019-11027-w

Cited by 104 publications

(90 citation statements)

References 34 publications

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“…Figure a shows the difference of climatological weighted

δ^{18} O_{P}

between P min and P max . Since there is a recharge threshold for rainfall infiltrating through karst systems, only months with precipitation amount larger than 150 mm/month are used to calculate the weighted

δ^{18} O_{P}

(Baker et al, ; Jones & Banner, ; Partin et al, ). It indicates that iCESM can simulate more negative weighted

δ^{18} O_{P}

in P min in the central and southern China as we expect based on speleothem records, but the amplitude is weaker (−1.6%0, compared with ∼ −4 to 5%0 in speleothem δ 18 O).…”

Section: Resultsmentioning

confidence: 99%

Deciphering Oxygen Isotope Records From Chinese Speleothems With an Isotope‐Enabled Climate Model

Emile‐Geay

Tabor

et al. 2019

Paleoceanog and Paleoclimatol

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Speleothem 18 O is widely used to reconstruct past hydroclimate variability, particularly over Asia. However, the interpretation of this proxy is still in debate. While this proxy is originally interpreted as regional rainfall amount of the Asian monsoon, other studies have interpreted it as upstream monsoon rainfall or atmospheric circulation changes. To better understand the signal preserved in speleothems over various time scales, this study employs a state-of-the-art isotope-enabled climate model to quantify contributions to the oxygen isotope composition of precipitation ( 18 O P ) over China. Results suggest that orbital-scale speleothem 18 O variations at Chinese sites mainly record the meridional migration of the Asian monsoon circulation, accompanied by an early northward movement of the East Asian rain belt. At interannual scales, Chinese speleothem 18 O is also tied to the intensity of monsoonal circulation, via a change in moisture source locations: Enhanced moisture delivery from remote source regions leads to more negative 18 O P , particularly in late summer and early autumn. Our results have implications for the hydroclimatic interpretation of speleothem 18 O from Chinese caves and suggest that this interpretation is time scale dependent.

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“…Figure a shows the difference of climatological weighted

δ^{18} O_{P}

δ^{18} O_{P}

(Baker et al, ; Jones & Banner, ; Partin et al, ). It indicates that iCESM can simulate more negative weighted

δ^{18} O_{P}

in P min in the central and southern China as we expect based on speleothem records, but the amplitude is weaker (−1.6%0, compared with ∼ −4 to 5%0 in speleothem δ 18 O).…”

Section: Resultsmentioning

confidence: 99%

Deciphering Oxygen Isotope Records From Chinese Speleothems With an Isotope‐Enabled Climate Model

Emile‐Geay

Tabor

et al. 2019

Paleoceanog and Paleoclimatol

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“…Furthermore, we have developed a mechanistic framework for why δ 13 C and δ 18 O values at this site would covary as a function of precipitation amount and cool season recharge (e.g. Baker et al, 2019) and the associated impacts on vegetation and, thereby, soil CO 2 . In years with high recharge (associated with increased precipitation) in the cool season, weighted δ 18 O precipitation values would be relatively low, which would be reflected in lower δ 18 O stalagmite values.…”

Section: Relationship Between Carbon and Oxygen Isotopes As Noted Ear-mentioning

confidence: 99%

Hydroclimate variability from western Iberia (Portugal) during the Holocene: Insights from a composite stalagmite isotope record

et al. 2020

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Iberia is predicted under future warming scenarios to be increasingly impacted by drought. While it is known that this region has experienced multiple intervals of enhanced aridity over the Holocene, additional hydroclimate-sensitive records from Iberia are necessary to place current and future drying into a broader perspective. Toward that end, we present a multi-proxy composite record from six well-dated and overlapping speleothems from Buraca Gloriosa (BG) cave, located in western Portugal. The coherence between the six stalagmites in this composite stalagmite record illustrates that climate (not in-cave processes) impacts speleothem isotopic values. This record provides the first high-resolution, precisely dated, terrestrial record of Holocene hydroclimate from west-central Iberia. The BG record reveals that aridity in western Portugal increased secularly from 9.0 ka BP to present, as evidenced by rising values of both carbon (δ13C) and oxygen (δ18O) stable isotope values. This trend tracks the decrease in Northern Hemisphere summer insolation and parallels Iberian margin sea surface temperatures (SST). The increased aridity over the Holocene is consistent with changes in Hadley Circulation and a southward migration of the Intertropical Convergence Zone (ITCZ). Centennial-scale shifts in hydroclimate are coincident with changes in total solar irradiance (TSI) after 4 ka BP. Several major drying events are evident, the most prominent of which was centered around 4.2 ka BP, a feature also noted in other Iberian climate records and coinciding with well-documented regional cultural shifts. Substantially, wetter conditions occurred from 0.8 ka BP to 0.15 ka BP, including much of the ‘Little Ice Age’. This was followed by increasing aridity toward present day. This composite stalagmite proxy record complements oceanic records from coastal Iberia, lacustrine records from inland Iberia, and speleothem records from both northern and southern Spain and depicts the spatial and temporal variability in hydroclimate in Iberia.

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“…U-Th isotopic compositions and concentrations were measured on a multicollector inductively coupled plasma mass spectrometer (Neptune, Thermo Fisher Scientific Inc.) at the High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC) of the Department of Geosciences at National Taiwan University (Shen et al, 2012). U-Th ages were calculated based on decay constants, half-lives and 238 U/ 235 U ratios (Jaffey et al, 1971;Cheng et al, 2013;Hiess et al, 2012). Uncertainties in the U-Th isotopic data and 230 Th dates (yr BP, before 1950 CE) are given at the two-sigma (2σ ) level or 2 standard deviations of the mean (2σ m ) unless otherwise noted.…”

Section: Isotope Measurementsmentioning

confidence: 99%

Experimental evaluation of oxygen isotopic exchange between inclusion water and host calcite in speleothems

et al. 2020

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Abstract. The oxygen and hydrogen isotopic compositions of water in fluid inclusions in speleothems are important hydroclimate proxies because they provide information on the isotopic compositions of rainwater in the past. Moreover, because isotopic differences between fluid inclusion water and the host calcite provide information on the past isotopic fractionation factor, they are also useful for quantitative estimation of past temperature changes. The oxygen isotope ratio of inclusion water (δ18Ofi), however, may be affected by isotopic exchange between the water and the host carbonate. Thus, it is necessary to estimate the bias caused by this postdepositional effect for precise reconstruction of paleotemperatures. Here, we evaluate the isotopic exchange reaction between inclusion water and host calcite based on a laboratory experiment involving a natural stalagmite. Multiple stalagmite samples cut from the same depth interval were heated at 105 ∘C in the laboratory from 0 to 80 h. Then, the isotopic compositions of the inclusion water were measured. In the 105 ∘C heating experiments, the δ18Ofi values increased from the initial value by 0.7 ‰ and then remained stable after ca. 20 h. The hydrogen isotope ratio of water showed no trend in response to the heating experiments, suggesting that the hydrogen isotopic composition of fluid inclusion water effectively reflects the composition of past drip water. We then evaluated the process behind the observed isotopic variations using a partial equilibration model. The experimental results are best explained by the assumption that a thin CaCO3 layer surrounding the inclusion reacted with the water. The amount of CaCO3 that reacted with the water is equivalent to 2 % of the water inclusions in molar terms. These results suggest that the magnitude of the isotopic exchange effect has a minor influence on paleotemperature estimates for Quaternary climate reconstructions.

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Global analysis reveals climatic controls on the oxygen isotope composition of cave drip water

Cited by 104 publications

References 34 publications

Deciphering Oxygen Isotope Records From Chinese Speleothems With an Isotope‐Enabled Climate Model

Deciphering Oxygen Isotope Records From Chinese Speleothems With an Isotope‐Enabled Climate Model

Hydroclimate variability from western Iberia (Portugal) during the Holocene: Insights from a composite stalagmite isotope record

Experimental evaluation of oxygen isotopic exchange between inclusion water and host calcite in speleothems

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