Climate of the Past

Deep ice cores from Antarctica, covering multiple glacial cycles, have provided an invaluable insight into climate dynamics on orbital and shorter timescales. Chronology is vital to the use of this archive. It is now timely to update the widely used EDC3 age scale. A new age scale is planned that will use modern Bayesian techniques to incorporate data from several different cores, along with improved dates and uncertainty estimates for individual age markers. The special issue will include papers that contribute information to the new AICC2012 age scale. This will include papers that propose new fixed markers and age constraints, new age estimates for existing markers, synchronisations between cores, ways to handle glaciological constraints, as well as papers discussing the overall methodology and presenting the new age scale itself.

Speleothems are highly valuable continental archives of past climate changes. The main aim of this special issue is to bring together contributions providing new insights in speleothem research. Of special interest are the processes driving the incorporation of various proxies in speleothems including O- and C-isotopes, trace elements, fluid inclusions, Mg-isotopes and non traditional proxies. We especially welcome contributions with focus on multi-proxy data series at very high resolution. We also encourage contributions on long term monitoring studies, which focus on recent regional climate variability and on processes involved in speleothem formation.

This special issue of Climate of the Past is the proceedings volume of the final workshop of project «LAMA» held at Fréjus (France) in March 2011. This project funded by the French ANR focused on the reconstruction of Holocene changes in environment and climate in the central Mediterranean. It is based on the study of sites along a north-south transect and on a combination of both marine and lacustrine records.

Low oxygen conditions (hypoxia) are becoming increasingly common in aquatic systems worldwide. While hypoxia can occur naturally due to stratification, eutrophication and limited bottom water renewal, there is strong evidence for a world-wide increase in hypoxia linked to human-activities and climate-change. This is of major concern because oxygen depletion leads to mortality of benthic fauna and major changes in ecosystem functioning. While true anoxia in the modern ocean is rare, wide-spread anoxia occurred episodically in the oceans during so-called oceanic anoxic events (OAEs) in Earth's past.

Numerous questions remain regarding the mechanisms driving hypoxia and anoxia in coastal and open ocean systems in the present and past, the role of natural processes versus human activities, the impacts on biota and the potential and timeline for (eco-) system recovery. This special issue of BG and CP aims to bring together papers on a broad range of aspects linked to oxygen depletion in modern and ancient settings addressing such questions.

This Special Issue originates from the PAGES initiative "Long-Term climate Reconstruction and Dynamics of southern South America: A collaborative, high-resolution multi-proxy approach" (LOTRED-SA). The Special Issue collates original research papers and reviews on paleoclimatic studies in southern South America over the past few millennia. Papers address the potential of different proxies for paleoclimatic reconstruction, present new datasets, and analyze regional features of model simulations. The topics covered complement those already presented in a first LOTRED-SA Special Issue published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology (Villalba et al., 2009).