PROCAVET

Proxies from cave deposits: testing their sensitivity using the current period of global change

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 Obiettivo del progetto (Objective)

'Speleothems are one of the better archives in the geological record to study low frequency paleoclimate changes at a high time resolution. Chronologies are well established via U-series radiometric dating or annual lamina counting. The information in speleothem records is provided by proxies, mainly geochemical, morphological and petrological properties of the sample analysed along its growth axis. However, proxy interpretation in terms of climate is complicated and needs calibration with monitoring studies, with pioneer studies that monitored cave climate and associated speleothems first done for the last two decades. However, both the cave environment and speleothems properties are expected to have changed since these early works due to the recent period of global climate change. So, the aim of this project is to evaluate if the present global warming and its associated climate effects are being recorded in cave environments and speleothems. Several caves from Europe where previous studies on cave environmental conditions and laminated speleothems have been undertaken are going to be revisited to analyse the changes in cave conditions since the earlier work. Laminated speleothems will be recovered from the same locations where previous samples were taken to study changes in the proxy record in the last decade(s). Speleothem climate proxies will be compared to changes in cave environmental conditions, and both the speleothem proxy data and cave climate conditions will be compared with known climate change as recorded in instrumental data from the nearest meteorological stations. The study will take special care in determining the response time of cave environments to changes in surface climate, and how fast these are transmitted to the speleothems. The noise contained within the climate signal in speleothem proxies will be evaluated, and precise transfer functions calculated with the aim to precisely calibrate speleothem proxies with climate parameters.'

Introduzione (Teaser)

Cave formations such as stalagmites have been investigated for their suitability for studying changes in climate over recent decades.

Descrizione progetto (Article)

Caves across Europe have been examined by scientists for signs of climate change. Researchers from the Procavet project identified five suitable study sites located in the United Kingdom, France, Spain and Slovenia. Experts monitored temperature and changes to the cave environment and cave formations for evidence of global warming. Earlier records of conditions within the caves were also recovered and compared with the latest findings.

Stalagmite samples were taken from all the different sites and analysed to determine the age of the cave. The results were compared with other techniques that employed hydrochemistry and Carbon-14 dating. Project partners also examined growth rates of stalagmites, which can give an indication of temperature changes over the previous decades.

A computer model was used to explain the transfer of heat from the surface to the cave below. The model enabled researchers to gain a better understanding of the processes involved in the transmission of temperatures. The depth of each gallery is critical to the caves response to environmental change as heat is mainly transferred through conduction. Other important processes, apart from climate change, which can affect the temperature within the cave, include land use and loss of forest cover.

Data from the Procavet project indicates that caves close to the surface are recording rises in temperature due to global warming, however, delays of up to several decades were recorded for galleries that are tens of metres deep. Work conducted by project partners showed that stalagmites were capable of recording environmental changes within the cave.

The study of caves and cave formations by the Procavet consortium will provide scientists with an additional technique for gaining evidence climate change and increase their understanding of the problem.