(e.g., rainfall). However, the water arriving at the end of a
stalactite is, in fact, a mixture of water from a variety of
networks of large and small micro-fissures which are more
or less complex, with a variable transfer time from the
exterior to the inner gallery (ranging from a few hours to
few weeks, months or years). This mixture was modeled
by A. Baker in a cave in Ethiopia, with components of
different ages: a small proportion (10–30%) of water
flowing quickly through the rock (from a few days to a few
weeks) and a greater proportion (70–90%), of the water
passing through slowly (months to a few years). The
variation in the amount of water arriving at the particular
stalagmite being studied (which largely determines the
thickness of the annual laminae) is calculated by applying
this mixture model to the rainfall provided by meteorological data. The proxy (the thicknesses, in this case) is
then compared with the amount of water supplying the
stalagmite (modeled using this simple mixture model). The
timeframe is given by the annual growth laminae. This
new method, applied to stalagmites in Ethiopia, has helped
to reconstruct summer rainfall over the last 80 years
(Baker et al. 2007). Other work is being developed around
the modeling of the d
18 O of infiltration water involving
reservoirs in the unsaturated zone (Fairchild and Baker
2012) or by empirical adjustment with modern climate data
(Domínguez-Villar et al. 2018).
Conclusion
Speleothems constitute continental paleoclimate records
that allow the reconstruction of climate changes on a precise
and absolute chronological timescale over the last
half-million years or more. They help to improve the accuracy of chronologies derived from other climate archives
and, depending on the site, can be used to reconstruct variations in rain intensity, rain source and vegetation density on the continent. However, to correctly interpret the
proxies measured in the speleothems, it is essential to know
the present day environment of the studied site: climate,
seasonality, hydrology, origin of the precipitations. Recent
methods of analysis of fluid inclusions and of Delta 47 create
opportunities to establish long series of continental temperature changes and of the isotopic composition of rainwater.
The recent proliferation of studies of speleothems and the
increasingly structured organization of the scientific community working on this archive (Karst Record symposiums
for example) have led to the discovery of important results
on climate change and their causes. Interactions between
increasingly large datasets (INTIMATE-Moreno et al. 2014,
SISAL database being constructed, Comas Bru et al. 2017)
and climate models are multiplying so as to better understand the processes and causes of climate variations.
References
Affolter, S., Fleitmann, D., & Leuenberger, M. (2014). New online
method for water isotope analysis of speleothem fluid inclusions
using laser absorption spectroscopy (WS-CRDS). Climate of the
Past, 10, 1291–1304. https://doi.org/10.5194/cp-10-1291-2014.
Arienzo, M. M., Swart, P. K., & Vonhof, H. B. (2013). Measurement of
d18O and d2H values of fluid inclusion water in speleothems using
cavity ring-down spectroscopy compared with isotope ratio mass
spectrometry. Rapid Communications in Mass Spectrometry, 27,
2616–2624. https://doi.org/10.1002/rcm.6723.
Baker, A., Asrat, A., Fairchild, I. J., Leng, M. J., Wynn, P. M., Bryant,
C., & Umer, M. (2007). Analysis of the climate signal contained
within delta O-18 and growth rate parameters in two ethiopian
stalagmites. Geochimica et Cosmochimica Acta, 71, 2975–2988.
Baker, A., Genty, D., Dreybrodt, W., Barnes, W. L., Mockler, N. J., &
Grapes, J. (1998). Testing theoretically predicted stalagmite growth
rate with recent annually laminated samples: Implications for past
stalagmite deposition. Geochimica et Cosmochimica Acta, 62,
393–404.
Baker, A., Hellstrom, J. C., Kelly, B. F. J., Mariethoz, G., & Trouet, V.
(2015). A composite annual-resolution stalagmite record of North
Atlantic climate over the last three millennia. Scientific Reports, 5,
10307. https://doi.org/10.1038/srep10307.
Boch, R., Cheng, H., Spötl, C., Edwards, R. L., Wang, X., &
Häuselmann, P. (2011). NALPS: A precisely dated European
climate record 120–60 ka. Climate of the Past Discussions, 7,
1049–1072. https://doi.org/10.5194/cpd-7-1049-2011.
Bourdin, C., Douville, E., & Genty, D. (2011). Alkaline-earth metal
and rare-earth element incorporation control by ionic radius and
growth rate on a stalagmite from the Chauvet Cave, Southeastern
France. Chemical Geology, 290, 1–11.
Cheng, H., Edwards, R. L., Sinha, A., Spötl, C., Yi, L., Chen, S., et al.
(2016). The Asian monsoon over the past 640,000 years and ice age
terminations. Nature, 534, 640–646. https://doi.org/10.1038/
nature18591.
Cheng, H., Lawrence Edwards, R., Shen, C.-C., Polyak, V. J.,
Asmerom, Y., Woodhead, J., et al. (2013). Improvements in
230Th dating, 230Th and 234U half-life values, and U-Th isotopic
measurements by multi-collector inductively coupled plasma mass
spectrometry. Earth and Planetary Science Letters, 371–372, 82–
91. https://doi.org/10.1016/j.epsl.2013.04.006.
Comas Bru, L., Burstyn, Y., & Scroxton, N. (2017). From caves to
climate: Creating the SISAL global speleothem database. Past
Global Change Magazine, 25, 156–156. https://doi.org/10.22498/
pages.25.3.156.
Combourieu Nebout, N., Turon, J. -L., Zahn, R., Capotondi, L.,
Londeix, L., & Pahnke, K. (2002). Enhanced aridity and atmospheric high-pressure stability over the western Mediterranean
during the North Atlantic cold events of the past 50 ky. Geology, 30
(10), 863–866.
Cruz Jr, F. W., Burns, S. J., Karmann, I., Sharp, W. D., Vuille, M.,
Cardoso, et al. (2005). Insolation-driven changes in atmospheric
circulation over the past 116,000 years in subtropical Brazil.
Nature, 434, 63–66.
Daeron, M., Guo, W., Eiler, J., Genty, D., Blamart, D., Boch, R., et al.
(2011). (13)C(18)O clumping in speleothems: Observations from
natural caves and precipitation experiments. Geochimica et Cosmochimica Acta, 75, 3303–3317.
Daeron, M., et al. (2008). Absolute speleo-thermometry, using clumped
isotope measurements to correct for kinetic isotope fractionations
induced by CO2 degassing. Geochimica et Cosmochimica Acta, 72,
A193–a193.
Domínguez-Villar, D., Lojen, S., Krklec, K., Kozdon, R., Edwards, R.
L., & Cheng, H. (2018). Ion microprobe d18O analyses to calibrate
14 Air-Ground Interface: Reconstruction of Paleoclimates …
175
stalactite is, in fact, a mixture of water from a variety of
networks of large and small micro-fissures which are more
or less complex, with a variable transfer time from the
exterior to the inner gallery (ranging from a few hours to
few weeks, months or years). This mixture was modeled
by A. Baker in a cave in Ethiopia, with components of
different ages: a small proportion (10–30%) of water
flowing quickly through the rock (from a few days to a few
weeks) and a greater proportion (70–90%), of the water
passing through slowly (months to a few years). The
variation in the amount of water arriving at the particular
stalagmite being studied (which largely determines the
thickness of the annual laminae) is calculated by applying
this mixture model to the rainfall provided by meteorological data. The proxy (the thicknesses, in this case) is
then compared with the amount of water supplying the
stalagmite (modeled using this simple mixture model). The
timeframe is given by the annual growth laminae. This
new method, applied to stalagmites in Ethiopia, has helped
to reconstruct summer rainfall over the last 80 years
(Baker et al. 2007). Other work is being developed around
the modeling of the d
18 O of infiltration water involving
reservoirs in the unsaturated zone (Fairchild and Baker
2012) or by empirical adjustment with modern climate data
(Domínguez-Villar et al. 2018).
Conclusion
Speleothems constitute continental paleoclimate records
that allow the reconstruction of climate changes on a precise
and absolute chronological timescale over the last
half-million years or more. They help to improve the accuracy of chronologies derived from other climate archives
and, depending on the site, can be used to reconstruct variations in rain intensity, rain source and vegetation density on the continent. However, to correctly interpret the
proxies measured in the speleothems, it is essential to know
the present day environment of the studied site: climate,
seasonality, hydrology, origin of the precipitations. Recent
methods of analysis of fluid inclusions and of Delta 47 create
opportunities to establish long series of continental temperature changes and of the isotopic composition of rainwater.
The recent proliferation of studies of speleothems and the
increasingly structured organization of the scientific community working on this archive (Karst Record symposiums
for example) have led to the discovery of important results
on climate change and their causes. Interactions between
increasingly large datasets (INTIMATE-Moreno et al. 2014,
SISAL database being constructed, Comas Bru et al. 2017)
and climate models are multiplying so as to better understand the processes and causes of climate variations.
References
Affolter, S., Fleitmann, D., & Leuenberger, M. (2014). New online
method for water isotope analysis of speleothem fluid inclusions
using laser absorption spectroscopy (WS-CRDS). Climate of the
Past, 10, 1291–1304. https://doi.org/10.5194/cp-10-1291-2014.
Arienzo, M. M., Swart, P. K., & Vonhof, H. B. (2013). Measurement of
d18O and d2H values of fluid inclusion water in speleothems using
cavity ring-down spectroscopy compared with isotope ratio mass
spectrometry. Rapid Communications in Mass Spectrometry, 27,
2616–2624. https://doi.org/10.1002/rcm.6723.
Baker, A., Asrat, A., Fairchild, I. J., Leng, M. J., Wynn, P. M., Bryant,
C., & Umer, M. (2007). Analysis of the climate signal contained
within delta O-18 and growth rate parameters in two ethiopian
stalagmites. Geochimica et Cosmochimica Acta, 71, 2975–2988.
Baker, A., Genty, D., Dreybrodt, W., Barnes, W. L., Mockler, N. J., &
Grapes, J. (1998). Testing theoretically predicted stalagmite growth
rate with recent annually laminated samples: Implications for past
stalagmite deposition. Geochimica et Cosmochimica Acta, 62,
393–404.
Baker, A., Hellstrom, J. C., Kelly, B. F. J., Mariethoz, G., & Trouet, V.
(2015). A composite annual-resolution stalagmite record of North
Atlantic climate over the last three millennia. Scientific Reports, 5,
10307. https://doi.org/10.1038/srep10307.
Boch, R., Cheng, H., Spötl, C., Edwards, R. L., Wang, X., &
Häuselmann, P. (2011). NALPS: A precisely dated European
climate record 120–60 ka. Climate of the Past Discussions, 7,
1049–1072. https://doi.org/10.5194/cpd-7-1049-2011.
Bourdin, C., Douville, E., & Genty, D. (2011). Alkaline-earth metal
and rare-earth element incorporation control by ionic radius and
growth rate on a stalagmite from the Chauvet Cave, Southeastern
France. Chemical Geology, 290, 1–11.
Cheng, H., Edwards, R. L., Sinha, A., Spötl, C., Yi, L., Chen, S., et al.
(2016). The Asian monsoon over the past 640,000 years and ice age
terminations. Nature, 534, 640–646. https://doi.org/10.1038/
nature18591.
Cheng, H., Lawrence Edwards, R., Shen, C.-C., Polyak, V. J.,
Asmerom, Y., Woodhead, J., et al. (2013). Improvements in
230Th dating, 230Th and 234U half-life values, and U-Th isotopic
measurements by multi-collector inductively coupled plasma mass
spectrometry. Earth and Planetary Science Letters, 371–372, 82–
91. https://doi.org/10.1016/j.epsl.2013.04.006.
Comas Bru, L., Burstyn, Y., & Scroxton, N. (2017). From caves to
climate: Creating the SISAL global speleothem database. Past
Global Change Magazine, 25, 156–156. https://doi.org/10.22498/
pages.25.3.156.
Combourieu Nebout, N., Turon, J. -L., Zahn, R., Capotondi, L.,
Londeix, L., & Pahnke, K. (2002). Enhanced aridity and atmospheric high-pressure stability over the western Mediterranean
during the North Atlantic cold events of the past 50 ky. Geology, 30
(10), 863–866.
Cruz Jr, F. W., Burns, S. J., Karmann, I., Sharp, W. D., Vuille, M.,
Cardoso, et al. (2005). Insolation-driven changes in atmospheric
circulation over the past 116,000 years in subtropical Brazil.
Nature, 434, 63–66.
Daeron, M., Guo, W., Eiler, J., Genty, D., Blamart, D., Boch, R., et al.
(2011). (13)C(18)O clumping in speleothems: Observations from
natural caves and precipitation experiments. Geochimica et Cosmochimica Acta, 75, 3303–3317.
Daeron, M., et al. (2008). Absolute speleo-thermometry, using clumped
isotope measurements to correct for kinetic isotope fractionations
induced by CO2 degassing. Geochimica et Cosmochimica Acta, 72,
A193–a193.
Domínguez-Villar, D., Lojen, S., Krklec, K., Kozdon, R., Edwards, R.
L., & Cheng, H. (2018). Ion microprobe d18O analyses to calibrate
14 Air-Ground Interface: Reconstruction of Paleoclimates …
175