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Spatiotemporal evolution of the hydrological cycle throughout the European continent during past abrupt climate changes

Periodic Reporting for period 4 - STEEPclim (Spatiotemporal evolution of the hydrological cycle throughout the European continent during past abrupt climate changes)

Reporting period: 2020-02-01 to 2020-07-31

The main aim of STEEPclim is to better constrain the regional impact of global climate (temperature) change on the hydrological cycle. Specifically, we use a period of abrupt temperature change in Earth history, the transition from the last Glacial to the Holocene between 13.000 and 10.000 years ago as an example of abrupt climatic change. During this period several major and abrupt temperature changes are recorded in the Greenland icecores, resulting in major environmental and ecosystem changes over continental Europe.
We investigate, how fast and how strongly these temperature changes cascaded into hydrological, environmental and ecosystem changes at 10+ locations covering Europe from northern Norway to southern Italy and southern Spain to northern Poland. The identification of spatial patterns and temporal leads and lags enables us to identify mechanisms of hydrological change, test the predictions of climate models and to identify particularly vulnerable regions to hydroclimatic changes.
The scientific progress is reported below structured by work packages (WP). Here I give the main achievements, more detail can be found under 1.1

WP1: We have now generated paleoclimate records from 18 lakes (10 were planned until the end of the project), significantly increasing the spatial coverage of our network.

Main result: the successful establishment and expansion of a network of 18 well-dated terrestrial climate archives and associated high-resolution hydrological records, see also publications by Jones et al. (2018), Ramos-Román et al. (2018)

WP2: A model to quantify hydrological reconstructions (DUB model) has been developed, work is published.

Main result 1: clear evidence that quantitative reconstruction of relative humidity change from sedimentary biomarker δD records is possible with the DUB model developed within STEEPclim – Publication Rach et al. 2017

Main result 2: evidence that lacustrine biomarker-based climate records are comparable on short timescales (i.e. several decades), through the study of two adjacent lake records (i.e. a replicate) and therefore enable regional comparisons of magnitude and timing of climate change events on multi-decadal timescales and is relevant beyond our project for any study on high-resolution lake records. Publication by Aichner et al. 2018, conference presentation by Grunwald et al. at INQUA 2019 (“Testing the sensitivity of decadally resolved n-alkane hydrogen isotope records of two adjacent lakes in northern Poland to Younger Dryas abrupt climatic change”)


WP3: Our datasets have allowed us now to identify spatial and temporal patterns of climate change:

Main Result 1: identification of a two-phased Younger Dryas period in Northern and Western/Central Europe and a more stable climate in Eastern Europe and the Mediterranean Sea due to atmospheric stabilizing mechanisms (conference presentation by Maas et al. INQUA 2019 (“Atmospheric trigger of a two-phased Younger Dryas in western Norway: Indications of local moisture source caused by a reduction in sea ice extent”), Sachse et al. at INQUA 2019 (“Influence of Atmospheric Circulation Changes on Spatiotemporal Patterns of European Hydroclimate During the Younger Dryas”)

Main Result 2: more pronounced multi-decadal variability in Western Europe during the second Younger Dryas phase as evidence for reestablishment of westerly atmospheric patterns (conference presentation by Rach et al. EGU 2020 “Reconstruction of regional humidity variations during the Younger Dryas - Holocene transition in NW Iberia using lipid biomarker stable isotope ratios“)
We have now generated paleoclimate records from 18 lakes (10 were planned until the end of the project), significantly increasing the spatial coverage of our network.

A model to quantify hydrological reconstructions (DUB model) has been developed, clear evidence that quantitative reconstruction of relative humidity change from sedimentary biomarker δD records is possible with the DUB model developed within STEEPclim – Publication Rach et al. 2017

We generated evidence that lacustrine biomarker-based climate records are comparable on short timescales (i.e. several decades), through the study of two adjacent lake records (i.e. a replicate) and therefore enable regional comparisons of magnitude and timing of climate change events on multi-decadal timescales and is relevant beyond our project for any study on high-resolution lake records. Publication by Aichner et al. 2018, conference presentation by Grunwald et al. at INQUA 2019 (“Testing the sensitivity of decadally resolved n-alkane hydrogen isotope records of two adjacent lakes in northern Poland to Younger Dryas abrupt climatic change”)

We identified a two-phased Younger Dryas period in Northern and Western/Central Europe and a more stable climate in Eastern Europe and the Mediterranean Sea due to atmospheric stabilizing mechanisms (conference presentation by Maas et al. INQUA 2019 (“Atmospheric trigger of a two-phased Younger Dryas in western Norway: Indications of local moisture source caused by a reduction in sea ice extent”), Sachse et al. at INQUA 2019 (“Influence of Atmospheric Circulation Changes on Spatiotemporal Patterns of European Hydroclimate During the Younger Dryas”)

We also found a more pronounced multi-decadal variability in Western Europe during the second Younger Dryas phase as evidence for reestablishment of westerly atmospheric patterns (conference presentation by Rach et al. EGU 2020 “Reconstruction of regional humidity variations during the Younger Dryas - Holocene transition in NW Iberia using lipid biomarker stable isotope ratios“)