Project

Predicting the magnitude and effects of future global warming is crucial for the development of adaptation tools meant to reduce the impact of environmental change on society. The economic importance of predicting this impact is associated, among others, to energy production and consumption. Modifications of rainfall patterns can disturb the output of hydropower plants, while modifications produced by aerosols in the quantity of solar radiation reaching the Earth's surface can impact the productivity of photovoltaic and solar thermal installations. Also, changes in biological conditions needed to grow energy crops can alter their contribution to the energy mix (DOE, 2013). Not least, changes in wind speed and direction can alter the energy production of wind farms. The renewable energy sector would not be the single affected in case of global warming, but also thermal power plants (nuclear and fossil) might see a 2-5% decrease in productivity only from lower cooling efficiency under increased temperatures (Mima et al., 2011). On the other hand, energy demand can be affected by changes in annual temperature, seasonality and extreme weather events. Under different models, the energy needed for cooling in Europe would increase with sustained global warming (Mima et al., 2011). The Global Circulation Models (GCMs) are thought to offer the important clues concerning the mechanisms and effects of climate changes The GCMs are based upon the study of past global changes and their effects at global and regional scales. While the public interest is focused on forecasting rapid climate oscillations and their immediate effects, studying such oscillations during the Anthropocene (or even the Holocene) is problematic owing to the difficulty of discriminating between 'noise' and 'true signal'. Even with high-resolution records, it is often hard to appreciate if detected regional lags are reflecting teleconnections or analytical artefacts. To help in discrimination, a strong signal is needed - a signal with an amplitude high enough to preclude noise and analytical uncertainties and be a reliable analogue to current conditions. At the same time, if one has to forecast regional climate developments in a warming Europe, one shall study an analogue to the Holocene which presumably experienced warmer temperatures than those of today. This analogue is the Eemian (MIS 5e), the closest-in-time period that may help researchers to understand how global warming has propagated across the Eurasian landmass, which were the factors involved and how they affected regions increasingly distant from the main source of climate change (in this case, the North Atlantic).

Key-questions to be answered

1. How far is the North Atlantic influencing the local climate across Eurasia?

2. What is the interaction between the NAO index across a West-East European transect and the Mediterranean and West Russia circulation, respectively?

3. What are the natural teleconnections between the Western and Eastern Europe, in the absence of industrially-triggered climate warming?

Aims and scope

This project proposes:

(i) to analyse climate relationships between Eastern and Western Europe during the last interglacial, in order to better understand how the European continent would be affected in case of sustained global warming. Previous work has indicated possible links between N Romania and S France during MIS 3 (60.000-30.000 years ago), presumably forced by the Atlantic precipitation regime (Drăgușin, 2013). During our project, we aim at studying speleothems from Tăușoare Cave (N Romania) and compare them to speleothems from S France (i.e. Villars, Demoiselles and Bourgeois Delaunay caves) in order to see if such relationships were also in place during MIS 5e. In addition, speleothem from S Romania will be analysed during our project, as this area was shown to have been under the influence of the Eastern Mediterranean during the Holocene (Drăgușin et al., 2014). Finally, speleothems from high elevations in the Southern Carpathians will be analysed, as this mountain range marks a limit between Mediterranean and Atlantic climate influences over Romania. The study of these different sites in Romania will give us a better perspective over regional MIS 5e climate dynamics and will help in understanding the links with Western Europe where more coeval speleothems have been studied (Genty et al., 2003; Weiner et al., 2011; Genty and Verheyden, 2013).

(ii) to analyse the timing of triggering of major climatic oscillations due to orbital cyclicity. We will analyse speleothems from S Romania and SW France that have recorded isotopic changes in regions affected predominantly by Mediterranean and Atlantic atmospheric circulation to check for potential time-lags.

(iii) to facilitate establishing reliable transfer functions between the speleothem isotopic record and the climatic parameters at surface. While speleothem δ¹⁸O and δ¹³C carry global and regional climate information, this information can be affected by local factors, specific to each cave under study (Genty et al., 2003; Fairchild et al., 2006). For a better understanding of site related conditions that can influence speleothem proxies, this project will establish a monitoring of the physical and chemical characteristics of cave atmosphere and infiltrating water (e.g. temperature, humidity, pCO₂, pH, conductivity, hardness, chemical composition), in parallel to monitoring of weather conditions on site and newly-formed calcite growing in the caves from both countries.

The project will:

(i) detail climate evolutions at regional and European scale during the Last Interglacial using speleothem proxies from France and Romania and

(ii) compare the Last Interglacial and Holocene climate dynamics at both regional and European scale.

The project involves:

(i) obtaining high resolution, accurately dated time series of speleothem climate proxies from caves in Romania (Tăușoare, North Carpathians; Cloșani and surroundings, SW Carpathians, Făgăraș, South Carpathians) and France (Villars, Demoiselles, Bourgeois Delaunay), covering the Last Interglacial;

(ii) monitoring local environmental factors in Romanian and French caves;

(iii) time series analysis of the newly produced geochemical records;

(iv) comparison of newly obtained climate records with published regional and global datasets;

(v) publishing the results in international journals and presenting them to international conferences.

Our methodology implies high resolution U-Th dating of speleothems using multi collector inductively coupled plasma mass spectrometery (MC-ICP-MS), the measurement of speleothem δ18O and δ13C using gas isotope ratio mass spectrometry (at LSCE, France), measurement of drip water δ18O and δD using cavity ring-down spectroscopy, measurement of the chemical composition of speleothems and drip waters using a quadrupole inductively coupled plasma mass spectrometer (at ISER, Romania). Physical and chemical measurements in the field will be undertaken using existent Vaisala and WTW portable multi-parameters for air pCO2, T and RH and water pH, T and σ, and AquaMerck carbonate hardness test kit for water. Data loggers mounted inside the studied caves will be used to record T, RH and cave water drip rates at 1-2 hours intervals. Current weather conditions will be recorded using professional Vaisala weather stations already installed by ISER at sites of interest. Newly precipitated carbonates will be harvested from glass plates installed under selected dripping points in monitoring stations. The project involves intensive fieldwork, with all parameters being measured in the field every second month in at least 3 caves from Southern and Northern Carpathians. Similar activities will be carried out in the French caves using a common protocol.

Preliminary (screening) U-Th dating of selected speleothems will be performed at the Geochronology laboratory (ISER, Romania) in order to assess the approximate ages and U-contents. It will be followed by ICP-MS high resolution dating to a partner laboratory and by the measurement of stable isotopes and chemical elements. A preliminary set of data should be obtained by the first project year, allowing the team to establish the best coeval records to be used for comparative studies. During the second year of the project, additional U-Th dating and stable isotope measurements will be done in order to obtain a higher detail in both the growth models and isotopic profiles of the studied speleothems. Following the construction of detailed isotopic profiles, correlations between Romanian and French records will be undertaken, also employing time series analysis in order to detail the teleconnections between the two regions. At the end of the second year preliminary transfer functions between surface parameters and underground precipitated calcite should be established.

Expected results

The results we foresee to stem from this project are linked to a better understanding of MIS 5e climate dynamics at regional and continental scale and the increased understanding of how the climate system would act at European scale in the future, in case of sustained warming. This will aid in the drawing of better adaptation policies to climate change at both national and European levels. While the EU adaptation policy to climate change was presented in 2013 and the Intergovernmental Panel on Climate Change 5^th Assessment Report is about to be published, our project will further add to the knowledge of past climate change and help in the societal adaptation to future global warming. Moreover, this program is complementary to the FP7 Past4Future Collaborative Project which is dedicated to the study of interglacial periods trough different archives and modelling (coord. Dorthe Dahl-Jensen, UCPH, Denmark and V. Masson-Delmotte, LSCE, France). Finally, the common activities of the two partner institutions, ISER and CEA, will contribute greatly to the prospect of them participating in joint European projects in the future.

The project will be carried out by a consortium which includes established researchers that have the required expertise to conduct high-quality research. We have planned that, beginning with the second half of 2015, the results will be presented to at least 2 international conferences annually. We expect an average of at least 2 papers per year to be published in international journals, with an increase in number during the final year. The results will also be available on the project's website. The published results will be available in electronic format at the World Data Center for Paleoclimatology (http://www.ngdc.noaa.gov).

The project will offer support for the integration of young researchers (3 PhD students, 2 postdoctoral) within the established research teams. We do believe that this is an important result since it will allow them to perform research while benefiting on the infrastructure available at national and international level.