Stable water isotopes in polar snow, firn and ice

Stable water isotopes in ice cores serve as a proxy for past changes in atmospheric temperature. Measuring and analyzing changes in the isotopic composition of ice cores enables us to reconstruct variability and changes of the climate in the past.

In our lab we measure the stable water isotopes δ18O, δ17O und δ2H in snow, firn and ice core samples from Greenland and Antarctica. Our focus lies in the combination of arrays of ice cores within one region in order to generate high-quality and reliable reconstructions of the past climate of the region. This enables us to analyze spatial and temporal changes of temperature in the past and to separate natural variability and long-term trends.

Another focus is the investigation of the signal formation. How is a climate signal stored at the snow surface? How is the climate signal modified after deposition and during the transformation from snow to ice? We support projects investigating snow surface processes, the exchange between atmosphere and snow and the post-depositional processes. Here we analyze snow samples from snow surface transects, snow profiles and 2-dimensional trenches of up to 4m depth.

For an optimal analysis and interpretation Stable Isotope Lab Potsdam and the research group Earth System Diagnosis. Here we combine our data with state-of-the-art methods in statistics.

A trench near Kohnen-Station, Antarctica with the spatial variability of stable water isotopes. (Photo: Alfred-Wegener-Institut)

Measurement techniques

Analysis of discrete samples
For the analysis of discrete samples (snow samples or subsamples from firn- and ice cores) we use Laser spectrometer (Cavity Ring Down Spectroscopy, Picarro Inc). These instruments are optimized for the measurement of hydrogen- and oxygen isotopes in water. Equipped with an autosampler and vaporizer the instruments only use few microliter per injection and can be operated in the field.

Continuous analysis of snow-, firn- and ice cores
In a combination of warm and cold laboratories we operate a melting unit for snow-, firn- and ice cores which enables us to measure continuously the stable water isotopes. The cores are melted on a specially designed melt-head in a cold-lab. The meltwater is pumped into the warm lab and directly analyzed for different parameter. For the measurement of stable water isotopes, the meltwater is vaporized in a spefically designed oven and injected in the laser spectrometer.

Laboratory work — Laboratory for the measurement of stable water isotopes in discrete samples: pipetting samples (Photo: Melanie Behrens)

Laser spectrometer with autosampler and vaporizer (Photo: Melanie Behrens)

Setup for continuous measurement of snow-, firn- and ice cores at AWI with a combination of warm and cold lab. (Photo: Melanie Behrens)

Current projects

Recent warming in Greenland

In this project we analyse an array of firn cores from Greenland. Due to the combination of all time series of stable water isotopes from these cores and the application of statistical methods we were able to show, that the 2001-2011 decade was the warmest in the past 1000 years in Greenland. These 10 years were 1.5 °C warmer than the 1961-1990 reference interval and 1.7 °C warmer than the 20th century.

Currently we are measuring the firn core extension until 2019.

Two graphs showing temperatures — Temperature time series from Greenland over the past 1000 years. (Graphic: Thomas Münch)

Drill camp with a polar airplane — Drill camp with Polar 5 in North-Greenland (Photo: Ole Zeising)

Contact

Scientific management: Maria Hörhold
maria.hoerhold@awi.de

Laboratory management: Melanie Behrens
melanie.behrens@awi.de

Technician: Elisa Conrad
elisa.conrad@awi.de

Head of ice core group: Frank Wilhelms
frank.wilhelms@awi.de

Publications

Hörhold, M., Münch, T., Weißbach, S. et al. Modern temperatures in central–north Greenland warmest in past millennium. Nature 613, 503–507 (2023).

Weißbach, S., Wegner, A., Opel, T., Oerter, H., Vinther, B. M., and Kipfstuhl, S.: Spatial and temporal oxygen isotope variability in northern Greenland – implications for a new climate record over the past millennium, Clim. Past, 12, 171–188, 2016.

Laepple, T., Münch, T., Hirsch, N. et al. Limitations of ice cores in reconstructing temperature seasonality. Nature 637, E1–E6 (2025).

Wahl, S., Steen-Larsen, H. C., Hughes, A. G., Dietrich, L. J., Zuhr, A., Behrens, M., et al. (2022). Atmosphere-snow exchange explains surface snow isotope variability. Geophysical Research Letters, 49, e2022GL099529.

Wahl, S., Steen-Larsen, H. C., Reuder, J., & Hörhold, M. (2021). Quantifying the stable water isotopologue exchange between snow surface and lower atmosphere by direct flux measurements. Journal of Geophysical Research: Atmospheres, 126, e2020JD034400.

Laepple, T., Münch, T., Casado, M., Hoerhold, M., Landais, A., and Kipfstuhl, S.: On the similarity and apparent cycles of isotopic variations in East Antarctic snow pits, The Cryosphere, 12, 169–187, 2018.

Dallmayr R, Freitag J, Hörhold M, et al. A dual-tube sampling technique for snowpack studies. Journal of Glaciology. 2021;67(261):84-90.

Hirsch, N., Zuhr, A., Münch, T., Hörhold, M., Freitag, J., Dallmayr, R., and Laepple, T.: Stratigraphic noise and its potential drivers across the plateau of Dronning Maud Land, East Antarctica, The Cryosphere, 17, 4207–4221, 2023.

Moser DE, Hörhold M, Kipfstuhl S and Freitag J (2020) Microstructure of Snow and Its Link to Trace Elements and Isotopic Composition at Kohnen Station, Dronning Maud Land, Antarctica. Front. Earth Sci. 8:23.

Münch, T., Kipfstuhl, S., Freitag, J., Meyer, H., and Laepple, T.: Regional climate signal vs. local noise: a two-dimensional view of water isotopes in Antarctic firn at Kohnen Station, Dronning Maud Land, Clim. Past, 12, 1565–1581, 2016

Münch, T., Kipfstuhl, S., Freitag, J., Meyer, H., and Laepple, T.: Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles, The Cryosphere, 11, 2175–2188, 2017.

Weinhart, A. H., Freitag, J., Hörhold, M., Kipfstuhl, S., and Eisen, O.: Representative surface snow density on the East Antarctic Plateau, The Cryosphere, 14, 3663–3685, 2020.