Abstract
Abstract. Ice core dating is the first step for a correct interpretation of climatic and environmental changes. In this work, we release the dating of the uppermost 197 m of the 250 m deep GV7(B) ice core (drill site, 70∘41′ S, 158∘52′ E; 1950 m a.s.l. in Oates Land, East Antarctica) with a sub-annual resolution. Chemical records of NO3-, MSA (methanesulfonic acid), non-sea-salt SO42- (nssSO42-), sea-salt ions and water stable isotopes (δ18O) were studied as candidates for dating due to their seasonal pattern. Different procedures were tested but the nssSO42- record proved to be the most reliable on the short- and long-term scales, so it was chosen for annual layer counting along the whole ice core. The dating was constrained by using volcanic signatures from historically known events as tie points, thus providing an accurate age–depth relationship for the period 1179–2009 CE. The achievement of the complete age scale allowed us to calculate the annual mean accumulation rate throughout the analyzed 197 m of the core, yielding an annually resolved history of the snow accumulation on site in the last millennium. A small yet consistent rise in accumulation rate (Tr = 1.6, p<0.001) was found for the last 830 years starting around mid-18th century.
Highlights
Ice cores represent remarkable natural archives able to provide paleoclimatic and paleoenvironmental information, and their study is of high relevance to improving our understanding of the climate system
New ice core records from Antarctica are needed for a better assessment of the surface mass balance (SMB) of the Antarctic continent, which is highly relevant for understanding its role in sea-level rise in recent decades and in the near future (DeConto and Pollard, 2016; Krinner et al, 2007)
Thomas et al (2017) investigated the Antarctic snow accumulation variability over the last millennium at regional scale using a large number of snow accumulation records, grouped and assigned to different regional Antarctic areas and compared them with modeled SMB
Summary
Ice cores represent remarkable natural archives able to provide paleoclimatic and paleoenvironmental information, and their study is of high relevance to improving our understanding of the climate system. The last millennium is a critical time frame for evaluating the more recent human-related climate change into a longer temporal context and to disentangle natural versus human impacts on climate variability, but it is still poorly investigated, in Antarctica. New ice core records from Antarctica are needed for a better assessment of the surface mass balance (SMB) of the Antarctic continent, which is highly relevant for understanding its role in sea-level rise in recent decades and in the near future (DeConto and Pollard, 2016; Krinner et al, 2007). Thomas et al (2017) investigated the Antarctic snow accumulation variability over the last millennium at regional scale using a large number of snow accumulation records, grouped and assigned to different regional Antarctic areas and compared them with modeled SMB
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