correspond to a source of precipitations which may vary
geographically over time. In addition, the isotopic composition of the ice may be affected by changes in altitude and
run-off, bringing to a drill site on the side of a dome, old ice
previously formed in a distant area, effects which need to be
taken into consideration (Masson et al. 2000).
Stable Isotopes of Air and Temperature
New methods to quantify abrupt changes of temperature
have been implemented, taking advantage of the thermal
fractionation of nitrogen or argon (whose isotopic composition is stable in the atmosphere over these time scales) that
occurs when air is trapped in the firn (Severinghaus et al.
1998). This approach reveals temperature change markers in
the gas phase, and also allows a more detailed characterization of the phase shifts between changes in atmospheric
composition (concentrations of greenhouse gases measured
in the gas phase) and changes in polar temperature.
This method does not allow an accurate estimate of the
temperature changes in the Antarctic, where gravitational
fractionation effects dominate, because changes in temperature are slower and less intense. However, it was used to
determine the phase shift between Antarctic warming and
increasing atmospheric concentrations of carbon dioxide
during deglaciations (Caillon et al. 2003).
In Greenland, study of the thermal fractionation of gases
was conducted on a series of rapid events, recorded in the ice
cores from GISP2, GRIP and NorthGRIP (Capron et al.
2010). Estimates of temperature changes through thermal
fractionation of the air have led to an upward revision of the
intensity of temperature changes during the warm
Dansgaard-Oeschger events, reaching an amplitude of 8 to
16 ± 3 °C, and have called into question the presumed
stability of the cold phases as they appear in the continuous
recordings of the stable isotopes of water. The apparent
discrepancy between the quantifications from the current
spatial relationship between water isotopes and temperature
and this alternative paleothermometry method can be
explained by significant changes in the seasonality of the
deposition of snow in Greenland over the ages, a process
highlighted by the climate-isotope models between the Last
Glacial Maximum and present times (Krinner 1997; Werner
et al. 2001).
Conclusions
It is important to note that a number of methods may be
applied to polar ice cores to quantify temperature changes.
New avenues are being explored to improve quantifications
of temperature change: isotopic measurements at very high
resolution in order to quantify isotopic diffusion, a process
which depends on the temperature; analysis of oxygen-17 in
water to more accurately estimate the evaporation conditions
(temperature, relative humidity) at the surface of the ocean;
continuous analysis of the isotopic composition of argon,
nitrogen and noble gases in order to characterize the thermal
and gravitational fractionations of the firn. Much remains to
be learned about the spatial and temporal variability of
temperatures in Greenland and Antarctica, both over recent
centuries and in the ancient climate cycles recorded in the
polar ice.
References
Caillon, N., Severinghaus, J. P., Jouzel, J., Barnola, J. M., Kang, J. and
Lipenkov, V. Y. (2003). Timing of atmospheric CO 2 and Antarctic
temperature changes across termination III. Science, 299, 1 728–1
731.
Capron, E., et al. (2010). Millennial and sub-millennial scale climatic
variations recorded in polar ice cores over the last glacial period.
Climate of the Past, 6, 345–365.
Ciais, P., Jouzel, J. (1994). Deuterium and Oxygen 18 in Precipitation:
An isotopic model including mixed cloud processes. Journal of
Geophysics Research, 99, 16 793–16 803.
Dahl-Jensen, D., Morgan, V. I., & Elcheikh, A. (1999). Monte carlo
inverse modeling of the law dome (Antarctica) temperature profile.
Annals of Glaciology, 29, 145–150.
Dahl-Jensen, D., Mosegaard, K., Gundestrup, N., Clow, G. D.,
Johnsen, S. J., Hansen, A. W., et al. (1998). Past temperatures
directly from the greenland ice sheet. Science, 282, 268–271.
Dansgaard, W. (1953). The abundance of
18
O in atmospheric water and
water vapour. Tellus, 5, 461–469.
Dansgaard, W. (1964). Stable isotopes in precipitation. Tellus, 16, 436–
468.
Dome Fuji Ice Core Project Members. (2017). State dependence of
climatic instability over the past 720,000 years from Antarctic ice
cores and and climate modeling. Science Advances, 3, e1600446.
Joussaume, S., Jouzel, J., & Sadourny, R. (1984). A general circulation
model of water isotope cycles in the atmosphere. Nature, 311,
24–29.
Jouzel, J., Vimeux, F., Caillon, N., Delaygue, G., Hoffmann, G.,
Masson-Delmotte, V., & Parrenin, F. (2003). Magnitude of the
isotope-temperature scaling for interpretation of central antarctic ice
cores. Journal of Geophysical Research, 108, 1029–1046.
Jouzel, J., Masson-Delmotte, V., Cattani, O., Dreyfus, G., Falourd, S.,
Hoffmann, G., et al. (2007a). Orbital and millennial Antarctic
climate variability over the past 800,000 years. Science, 317, 793–
797. https://doi.org/10.1126/science.1141038.
Jouzel, J., Stiévenard, M., Johnsen, S. J., Landais, A.,
Masson-Delmotte, V., Sveinbjornsdottir, A., et al. (2007b).
The GRIP deuterium-excess record. Quaternary Science Reviews,
26, 1–17.
Koerner, R. M., & Fisher, D. A. (2002). Ice-Core evidence for
widespread arctic glacier retreat in the last interglacial and the early
Holocene. Annals of Glaciology, 35, 19–24.
Krinner, G., C. Genthon, and J. Jouzel (1997). GCM analysis of local
influences on ice core d signals. Geophysical Research Letters, 24,
2 825–2 828.
Masson, V., Vimeux, F., Jouzel, J., Morgan, V., Delmotte, M.,
Hammer, C., et al. (2000). Holocene Variability in Antarctica based
on 11 ice core isotopic records. Quaternary Research, 54, 348–358.
148
V. Masson-Delmotte and J. Jouzel
geographically over time. In addition, the isotopic composition of the ice may be affected by changes in altitude and
run-off, bringing to a drill site on the side of a dome, old ice
previously formed in a distant area, effects which need to be
taken into consideration (Masson et al. 2000).
Stable Isotopes of Air and Temperature
New methods to quantify abrupt changes of temperature
have been implemented, taking advantage of the thermal
fractionation of nitrogen or argon (whose isotopic composition is stable in the atmosphere over these time scales) that
occurs when air is trapped in the firn (Severinghaus et al.
1998). This approach reveals temperature change markers in
the gas phase, and also allows a more detailed characterization of the phase shifts between changes in atmospheric
composition (concentrations of greenhouse gases measured
in the gas phase) and changes in polar temperature.
This method does not allow an accurate estimate of the
temperature changes in the Antarctic, where gravitational
fractionation effects dominate, because changes in temperature are slower and less intense. However, it was used to
determine the phase shift between Antarctic warming and
increasing atmospheric concentrations of carbon dioxide
during deglaciations (Caillon et al. 2003).
In Greenland, study of the thermal fractionation of gases
was conducted on a series of rapid events, recorded in the ice
cores from GISP2, GRIP and NorthGRIP (Capron et al.
2010). Estimates of temperature changes through thermal
fractionation of the air have led to an upward revision of the
intensity of temperature changes during the warm
Dansgaard-Oeschger events, reaching an amplitude of 8 to
16 ± 3 °C, and have called into question the presumed
stability of the cold phases as they appear in the continuous
recordings of the stable isotopes of water. The apparent
discrepancy between the quantifications from the current
spatial relationship between water isotopes and temperature
and this alternative paleothermometry method can be
explained by significant changes in the seasonality of the
deposition of snow in Greenland over the ages, a process
highlighted by the climate-isotope models between the Last
Glacial Maximum and present times (Krinner 1997; Werner
et al. 2001).
Conclusions
It is important to note that a number of methods may be
applied to polar ice cores to quantify temperature changes.
New avenues are being explored to improve quantifications
of temperature change: isotopic measurements at very high
resolution in order to quantify isotopic diffusion, a process
which depends on the temperature; analysis of oxygen-17 in
water to more accurately estimate the evaporation conditions
(temperature, relative humidity) at the surface of the ocean;
continuous analysis of the isotopic composition of argon,
nitrogen and noble gases in order to characterize the thermal
and gravitational fractionations of the firn. Much remains to
be learned about the spatial and temporal variability of
temperatures in Greenland and Antarctica, both over recent
centuries and in the ancient climate cycles recorded in the
polar ice.
References
Caillon, N., Severinghaus, J. P., Jouzel, J., Barnola, J. M., Kang, J. and
Lipenkov, V. Y. (2003). Timing of atmospheric CO 2 and Antarctic
temperature changes across termination III. Science, 299, 1 728–1
731.
Capron, E., et al. (2010). Millennial and sub-millennial scale climatic
variations recorded in polar ice cores over the last glacial period.
Climate of the Past, 6, 345–365.
Ciais, P., Jouzel, J. (1994). Deuterium and Oxygen 18 in Precipitation:
An isotopic model including mixed cloud processes. Journal of
Geophysics Research, 99, 16 793–16 803.
Dahl-Jensen, D., Morgan, V. I., & Elcheikh, A. (1999). Monte carlo
inverse modeling of the law dome (Antarctica) temperature profile.
Annals of Glaciology, 29, 145–150.
Dahl-Jensen, D., Mosegaard, K., Gundestrup, N., Clow, G. D.,
Johnsen, S. J., Hansen, A. W., et al. (1998). Past temperatures
directly from the greenland ice sheet. Science, 282, 268–271.
Dansgaard, W. (1953). The abundance of
18
O in atmospheric water and
water vapour. Tellus, 5, 461–469.
Dansgaard, W. (1964). Stable isotopes in precipitation. Tellus, 16, 436–
468.
Dome Fuji Ice Core Project Members. (2017). State dependence of
climatic instability over the past 720,000 years from Antarctic ice
cores and and climate modeling. Science Advances, 3, e1600446.
Joussaume, S., Jouzel, J., & Sadourny, R. (1984). A general circulation
model of water isotope cycles in the atmosphere. Nature, 311,
24–29.
Jouzel, J., Vimeux, F., Caillon, N., Delaygue, G., Hoffmann, G.,
Masson-Delmotte, V., & Parrenin, F. (2003). Magnitude of the
isotope-temperature scaling for interpretation of central antarctic ice
cores. Journal of Geophysical Research, 108, 1029–1046.
Jouzel, J., Masson-Delmotte, V., Cattani, O., Dreyfus, G., Falourd, S.,
Hoffmann, G., et al. (2007a). Orbital and millennial Antarctic
climate variability over the past 800,000 years. Science, 317, 793–
797. https://doi.org/10.1126/science.1141038.
Jouzel, J., Stiévenard, M., Johnsen, S. J., Landais, A.,
Masson-Delmotte, V., Sveinbjornsdottir, A., et al. (2007b).
The GRIP deuterium-excess record. Quaternary Science Reviews,
26, 1–17.
Koerner, R. M., & Fisher, D. A. (2002). Ice-Core evidence for
widespread arctic glacier retreat in the last interglacial and the early
Holocene. Annals of Glaciology, 35, 19–24.
Krinner, G., C. Genthon, and J. Jouzel (1997). GCM analysis of local
influences on ice core d signals. Geophysical Research Letters, 24,
2 825–2 828.
Masson, V., Vimeux, F., Jouzel, J., Morgan, V., Delmotte, M.,
Hammer, C., et al. (2000). Holocene Variability in Antarctica based
on 11 ice core isotopic records. Quaternary Research, 54, 348–358.
148
V. Masson-Delmotte and J. Jouzel