Topographic effect creates non-climatic variations in ice-core based
temperature records of the last millennium
- Remi Dallmayr,
- Johannes Freitag,
- Thomas Laepple,
- Frank Wilhelms,
- Daniela Jansen,
- Melanie Behrens,
- Maria Winona Hoerhold
Remi Dallmayr
Alfred Wegener Institut for Polar and Marine Reasearch
Author ProfileThomas Laepple
Alfred Wegener Institute for Polar and Marine Research
Author ProfileFrank Wilhelms
Alfred Wegener Institute for Polar and Marine Sciences
Author ProfileDaniela Jansen
Alfred Wegener Institute for Polar and Marine Research
Author ProfileMelanie Behrens
Alfred Wegener Institut for Polar and Marine Reasearch
Author ProfileMaria Winona Hoerhold
Alfred Wegener Institute for Polar and Marine Research
Author ProfileAbstract
Past temperature reconstructions from polar ice sheets are commonly
based on stable water isotope records in ice-cores. However, despite
major efforts in the understanding of the ice-core signal formation, the
temperature reconstructions of the last millennium in Antarctica remain
highly uncertain. Here, using a 100 km scale representative surface
water isotope dataset, we show that the spatial variability of local
surface topography and accumulation rate anomalies influences the
isotopic composition of the upper-meter snowpack. The magnitude of this
non-temperature effect on water isotopes is similar to changes of the
last millennium. We demonstrate that these spatial anomalies are
advected into the deeper firn and ice column, and are translated into an
artificial centennial to millennial scale variability in the isotope
record. Additionally, we provide an estimation of areas where this
effect is relevant for last millennium temperature reconstructions.