Ongoing Global warming currently represents one of the major societal challenges. To address this challenge, policy makers need tailored and accurate climate information. As stated by the latest IPCC report, global temperature at the end of the 21st century is likely to exceed +1.5°C relative to 1850-1900, will exhibit interannual-to-decadal variability and will not be regionally uniform. The precision and spatial and temporal resolution of current models still remain insufficient to use the obtained projections for efficient adaptation and mitigation policies, which require higher resolution. To feed and test climate models, robust information on the climate system is necessary. Important in this context are the timing, duration, intensity and variability of temperature and rainfall changes at higher spatial (downscaling) and temporal resolution (better constrained chronology).

In the North-Western part of Europe and precisely in Normandy (France), there is a lack of well-dated natural archives that are able to record past and current climate change variability at high-resolution. Therefore, the reconstruction of past environmental and anthropogenic forcings on ecosystems require robust and well-preserved archives. Previous work undertaken on the Seine estuary dates back only to the last 8,500 years BP with a reconstruction of climato-eustatic oscillations at low resolution. Various studies on Normand hydrosystems reconstructed paleoclimate variability and forcing on landscape and ecosystem mutations, but only at an infra-millennial scale.

Speleothem (cave deposits) archives provide this information through the study of their petrography, geochemical content and their possibility of precise absolute dating, combined with annual layer counting. Geomorphological and sedimentological study of the cave environment and cave area provides the environmental context of the climate changes and their local and regional impacts.

New speleothems retrieved from the Quarries and Cave of Caumont system (Eure) and the Quarries of Caen will be investigated in PAL-ECO-NOR project through laminae counting, C14 and U/Th dating methods and geochemical analysis on stalagmites spanning the last 11.000 years. This project aims to:

date the speleogenesis context of Caumont multi cave-level system,
reconstruct at high resolution the climate variabilities from the late-Holocene to the contemporaneous era using stable isotopes,
date the exploitation of quarries during Medieval times and iv) trace the anthropogenic paleo-pollution in the 20th & 21st centuries using trace elements.

One of the main deliverables of this project funded is to provide new paleoenvironmental and paleoclimatic records for Normandy at a decadal to sub-decadal scale.

Financement: RIN Émergeant région Normandie, ARTEMIS 2020 CNRS INSU

Partners:

• Étude et Compréhension de la Biodiversité - ECODIV URA IRSTEA-EA 1293
• FR CNRS 3730 SCALE, Normandie
• Environnements Dynamiques et Territoires de la Montagne - EDYTEM 5204 CNRS, France
• Laboratoire des Sciences du Climat - LSCE 8212 CNRS, France
• NERC Isotope Geoscience laboratory - British Geological Survey, United Kingdom

Collaborators:

• Comité Régional de Spéléologie (FFS)
• Centre Normand d’Étude du Karst