In:
Climate of the Past, Copernicus GmbH, Vol. 19, No. 6 ( 2023-06-07), p. 1125-1152
Abstract:
Abstract. The temperature of the Earth is one of the most important
climate parameters. Proxy records of past climate changes, in particular
temperature, represent a fundamental tool for exploring internal climate processes
and natural climate forcings. Despite the excellent information provided by
ice core records in Antarctica, the temperature variability of the past 2000
years is difficult to evaluate from the low-accumulation sites in the
Antarctic continent interior. Here we present the results from the Aurora
Basin North (ABN) ice core (71∘ S, 111∘ E, 2690 m a.s.l.) in the lower part of the East Antarctic plateau, where accumulation
is substantially higher than other ice core drilling sites on the plateau,
and provide unprecedented insight into East Antarctic past temperature
variability. We reconstructed the temperature of the last 2000 years using
two independent methods: the widely used water stable isotopes (δ18O) and by inverse modelling of borehole temperature and past
temperature gradients estimated from the inert gas stable isotopes (δ40Ar and δ15N). This second reconstruction is based on
three independent measurement types: borehole temperature, firn thickness,
and firn temperature gradient. The δ18O temperature
reconstruction supports stable temperature conditions within 1 ∘C
over the past 2000 years, in agreement with other ice core δ18O
records in the region. However, the gas and borehole temperature
reconstruction suggests that surface conditions 2 ∘C cooler than
average prevailed in the 1000–1400 CE period and supports a 20th
century warming of 1 ∘C. A precipitation hiatus during cold
periods could explain why water isotope temperature reconstruction
underestimates the temperature changes. Both reconstructions arguably record
climate in their own way, with a focus on atmospheric and hydrologic cycles
for water isotopes, as opposed to surface temperature for gas isotopes and
boreholes. This study demonstrates the importance of using a variety of
sources for comprehensive paleoclimate reconstructions.
Type of Medium:
Online Resource
ISSN:
1814-9332
DOI:
10.5194/cp-19-1125-2023
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2023
detail.hit.zdb_id:
2217985-9
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