The main objective of the DOMINO-CLIMATE project is to combine a general narrative of changes with detailed local paleoclimate, eDNA and archeobotanical studies in order to shed light on regional differences or coincidences in the timing of climatic changes (both rapid and longer-term). We also aim to reconstruct the composition of Late Neolithic and Copper Age (Eneolithic or Chalcolithic) terrestrial ecosystems and subsistence economy along two relatively large geographical transect (W-E: from Hungary to Ukraine, N-S: from Ukraine to Bulgaria) and to apply novel paleoclimate reconstruction techniques (brGDGT) in areas seriously under-investigated in the Balkan Region (Serbia, Montenegro). In our unique multidisciplinary approach our objective is to integrate the paleoclimate, paleoenvironmental and bio-archaeological data with geo-informatics and archaeology using a big-data approach. It will constitute a major step forward in order to explain the causes of the end of the NC in the target area (Fig. 1) between 4550-3300 cal. BC. The focus on (South-) Eastern Europe - Bulgaria, Romania, Ukraine, Hungary, Serbia and Montenegro (BG, RO, UA, HU, SRB, MNE) is not accidental, especially since we have a sound overall AMS-based chronology which suggests that the decline of the flourishing European NC started from East to West and North to South (Domino Effect). We propose that this effect made inter-regional changes more likely, since a social and settlement collapse in one region would have had a knock-on effect on communications and exchange networks in the next region, and so on.

Since quantitative climate reconstructions covering the mid-Holocene are available in limited number from the study region, our aim with this project is to increase the number of quantitative reconstructions, and the spectrum of reconstructed climatic variables (MAT, MTWA, PANN, GDD5, PET/AET). Available records are based on pollen analysis, stable oxygen and carbon isotopes from stalagmite, diatom assemblages, chironomids and one brGDGT record.

Hypothesis 1: RCC 6.2-5 kyr cal BP recognized by Wenninger and Harper [2015] characterised by increased Siberian High circulation pattern brought cold air spells in late winter and early spring to SE Europe, and these seasonal short-lived cold spells contributed to population decline, tell abandonment and a switch from an agrarian (tell-based) economy to a pastoral one in Romania, Bulgaria, Hungary and Serbia.

Project objective: use early spring sensitive proxies (e.g. diatom-based pH or diatom-silica based d18O records) to evaluate the hypothesis; note that annual or summer mean temperature reconstructions are not capable to address this hypothesis

Hypothesis 2: The time-transgressive collapse of the LN tells in the study region was driven by differential climate change in the eastern and western sector of the study region and the different expression of RCC events in the study region (Fig. 1) that was triggered by a reversal from NAO- to NAO+ dominance in EC and SE Europe, summer insolation decrease, and winter insolation increase.

Project objective: use stable isotope, pollen, chironomid and lipid biomarker (brGDGT) based climate reconstruction, with particular attention to the reconstruction of bioclimatic parameters (growing-degree day, AET/PET) to verify the proposed climate change in the region and further examine its spatial manifestation.

Hypothesis 3: Terrestrial ecosystems and the conditions of arable farming has changed considerably over the NC collapse interval (4550-3200 cal BC) due to solar activity driven changes in the macroclimate.

Project objective: Build a pollen database on this period from existing and new pollen records from the region and carry out quantitative vegetation reconstruction to demonstrate the regional vegetation trajectory between 4550-3300 cal BC. Compile a database on LN charcoal and carpological records from the study region (e.g. using older seed and charcoal collections published by Marin Carciumaru in RO) and compare the two independent line of evidence to reconstruct regional similarities and differences in the vegetation trajectories, and use these records to draw conclusions on the role of natural terrestrial ecosystem change in the change of subsistence economies.