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Vegetation dynamics and carbon sequestration of Holocene alder (Alnus glutinosa) carrs of NE Germany
(2010)
Erlenwälder auf Moorstandorten werden oft als Zeichen von Moordegradation und Torfoxidation gewertet, aber erlenholzreiche Moorablagerungen (teilweise mehrere Meter tief) sind unter anderem in Nordostdeutschland weit verbreitet. Die Genese von Erlen-Holztorfen wurde bisher überwiegend durch das Konzept der „Verdrängungstorfbildung“ erklärt. Hierbei wird ein von gehölzfreier Vegetation akkumulierter Torf nach einer Grundwasserabsenkung durch nachträglich einwachsende Baumwurzeln verändert. Dieses Prinzip ist aber auf tiefgründige Erlen-Holztorfe nicht übertragbar, da Alnus glutinosa auf naturnahen Moorstandorten meist nur wenige Dezimeter tief wurzelt. Anliegen der vorliegenden Dissertation mit dem Titel „Vegetation dynamics and carbon sequestration of Holocene alder (Alnus glutinosa) carrs in NE Germany“ war die Identifizierung torfbildender Erlenwälder. Die torfbildende Vegetation, die Wasserstände während der Torfbildung und die Vegetationsdynamik dieser bewaldeten Niedermoore wurden durch Analysen von Makrofossilien, Pollen und sonstigen Mikrofossilien (u.a. Pilz-, Pflanzen-, und tierische Reste) rekonstruiert. Hierbei wurden in enger Kooperation mit dem Promotionsvorhaben von Frau Anja Prager (Non-pollen palynomorphs [NPPs] from modern alder carrs [NE Germany] - Tools for reconstructing past vegetation and site conditions) ca. 150 bisher unbekannte Mikrofossilien beschrieben und teilweise identifiziert. Die Datenauswertung wurde anhand von Fossilien-Diagrammen und statistischen Methoden (DCA, Clusteranalysis; Broken Stick Analysis) durchgeführt. Zur Altersbestimmung erfolgten 14C-AMS-Datierungen und der Kohlenstoffgehalt wurde über die Bestimmung der Trockenrohdichte ermittelt, wobei ein durchschnittlicher Kohlenstoffanteil von 56% angenommen wurde. Die untersuchten Erlen-Holztorfe wurden überwiegend direkt in Erlenwäldern abgelagert („Echter Bruchwaldtorf“); sind aber auch teilweise als Verdrängungstorfe aus vorherigen Seggentorfen entstanden oder in von Weiden dominierten Gehölzen gebildet worden. Die jährlichen Medianwasserstände der torfbildenden Erlenwälder lagen einerseits über Flur („sehr nass“-„very wet“) und zum anderen 0 bis 10 cm unter Flur („nass“ - „wet“). Die Vegetationszusammensetzung der sehr nassen Erlenwälder ähnelte teilweise dem Wasserfeder-Erlen-Wald und in einem Fall dem Zweizahn-Erlen-Bruchgehölz. Die nassen Erlenwälder konnten nicht auf der Ebene von Vegetationsformen rekonstruiert werden; charakteristisch war das häufige Auftreten von Urtica und eine Carex-dominierte Krautschicht. Über einen Vergleich der Mikrofossilien der Erlenholz-Tofe mit Mikrofossilien von Oberflächenproben aus rezenten Erlenwäldern konnten die Medianwasserstände nasser, torf-akkumulierender Erlenwälder auf 0-10 cm unter Flur festgelegt werden. Alle untersuchten Profile zeigten eine zyklische Bewaldung mit Zwischenphasen von Offenvegetation (meist Seggenriede). Als Bindeglieder zwischen Erlenwald und Seggenried traten teilweise Weidengebüsche auf, welche sich mitunter auch langfristiger etablieren konnten. Die zyklische Vegetationsentwicklung von Seggenrieden, Weidengebüschen und Erlenwäldern basierte fast ausschließlich auf einem schwankenden Wasserangebot im Moor. Dieses war fast immer die Folge von zyklischen Ent- und Wiederbewaldungen der umliegenden, grundwasserfernen Standorte durch den Menschen. Die „Echten Bruchwaldtorfe“ sind unter verschiedenen hydrologischen Bedingungen entstanden (Verlandungs-, Versumpfungs-, Überrieselungs- und Überflutungsmoor). Die Kohlenstoff-Akkumulationsraten („LORCA“-long-term apparent rate of carbon accumulation) liegen zwischen 31-44 g C m-2 yr-1 in sehr nassen und 50-81 g C m-2 yr-1 in nassen Erlenwäldern. Die höheren Akkumulationsraten in nassen Erlenwäldern können durch die deutlich steigende Produktivität von Erlen-Wäldern schon bei leicht sinkenden mittleren Wasserständen erklärt werden. Eine Verringerung der durchschnittlichen Wasserstände von über Flur zu leicht unter Flur führt annähernd zu einer Verdopplung der Primärproduktion von oberirdischem Holz und Wurzelholz. Dadurch gelangt auch ein größerer Anteil von Wurzelholz in den dauerhaft wassergesättigten Bereich. Da mit sinkenden Wasserständen auch die oxidative Zersetzung zunimmt, ist für die teilweise sehr hohen Torfakkumulationsraten in Erlenwäldern die Zersetzungsresistenz von Holz (Lignin) von zentraler Bedeutung. Die Akkumulationsraten nasser Erlenwälder übersteigen die borealer Waldmoore deutlich und erreichen die Größenordnung der Kohlenstoffakkumulation in den tropischen Waldmooren Süddostasiens. Die vorliegende Dissertation belegt die weitverbreitete und oft umfangreiche Torf- bzw. Kohlenstoffakkumulation in Holozänen Erlen-Wäldern Nordostdeutschlands.
Late Quaternary evolution and carbon cycling of tropical peatlands in equatorial Southeast Asia
(2014)
Peatlands are an important component in the global carbon cycle as they act as both long-term sinks for carbon dioxide and significant sources for methane. Over the Holocene period (the past 11,700 years) continuous CO2 uptake by peat accumulation exceeded methane emissions in northern peatlands and resulted in a net-radiative cooling effect on the global climate.Although 11% of the global peatland area is located in the tropics, the role of tropical peatlands in the global carbon cycle and in influencing the Earth’s radiative budget has not been resolved. Climate-carbon cycle models have thus far not included tropical peatlands because reliable data on their past rates of carbon uptake and release are not available. In this thesis this problem has been approached by reconstructing peatland expansion and rates of carbon storage and release over the Late Quaternary (Latest Pleistocene and Holocene) for the largest tropical peatland area, which is located in equatorial SoutheastAsia (i.e. Sumatra, Borneo, Peninsular Malaysia). Peat accumulation in the tropics remains an enigmatic phenomenon, because the constantly high temperatures of 26-27°C should theoretically drive rapid soil carbon turnover and thus not enable the accumulation of peat. Therefore this thesis also explores the mechanisms that cause peat formation in the SoutheastAsian tropics as well as the drivers behind changing rates of carbon accumulation. Carbon dynamics were analyzed at the regional scale (103–105 km2) of SoutheastAsia over millennial timescales (paper, I, II) and at the local scale (101–102 m2) of a peatland site on annual to centennial timescales (paper III, IV). Paper I presents the first systematic classification of the nearly 160,000 km2 SoutheastAsian lowland peatlands (below 70 m a.s.l.) into geographic peatland types. The peatlands were divided into 1) coastal peatlands of PeninsularMalaysia, Sumatra, and Borneo (~130,000 km2) and into inland peatlands (~30,000 km2) of 2) Central Kalimantan (southern Borneo), 3) the Kutai basin (eastern Borneo), and 4) the Upper Kapuas basin (western Borneo). Coastal peatlands formed by primary mire formation directly on freshly exposed marine or mangrove soils with the lowering of the sea level during the Late Holocene. In contrast, inland peatlands formed via paludification on either terrestrial sand soils (Central Kalimantan) or by both paludification and terrestrialization (Kutai basin, Upper Kapuas basin). The sequence of peatland initiation was established by applying the common cumulative basal date frequency approach (paper I). This method revealed clear differences in the timing of peatland initiation: 1) the Upper Kapuas peatlands are the oldest postglacial peat formations and date from 20,000-13,000 cal BP (calendar years before present), 2) inland Central Kalimantan peatlands date from 14,500-9000 cal BP, 3) the Kutai peatlands date from 8300-4900 cal BP, and 4) and the coastal peatlands date from 7700-200 cal BP. Coastal peatlands have a Holocene average carbon accumulation rate of 77 g C m-2 yr-1, being recognized as the globally most effective terrestrial ecosystems in terms of long-term carbon sequestration. Except for the Kutai peatlands, the Holocene average carbon accumulation rates of inland peatlands are significantly lower (20-30 g C m-2 yr-1) and very similar to the average long-term rates of northern peatlands. Fluctuations in past rates of carbon accumulation of SoutheastAsian peatlands could for the first time be linked to paleoclimatic changes, primarily variations in moisture availability (paper I, II). Hydroclimatic influences on carbon accumulation rates were related to shifts in the mean position of the Intertropical Convergence Zone, changes in the intensity of theAustral-Asian monsoon system, and variations in the frequency of the El Niño- Southern Oscillation. In contrast, peatland initiation and expansion was driven by sea-level change (paper I, II). The deglacial rise in sea-level is identified as the primary driver for inland peatland formation in Borneo, because the rising sea-level 1) lowered the hydrological gradients in the SoutheastAsian island archipelago inducing rising ground and surface water levels on these islands, and 2) led to higher atmospheric moisture availability due to the associated expansion of marine water masses on the shelf floor. Paper II shows that inland peatland initiation and expansion was most extensive during deglacial meltwater pulses, when the rate of sea-level rise exceeded 10 mm yr-1. Only when the rate of sea-level rise had slowed down to a threshold of 2.4 mm yr-1 by ~7000 cal BP could peat accumulation along the coasts keep up with the sea-level rise and coastal peatlands could form. Hydro-isostatic adjustment of the Sunda Shelf led to a sea-level lowering by ca. 5 m over the past 4500 years. Falling sea levels exposed extensive marine areas that were rapidly colonized by peat swamp forests.Anewly 140 developed method for the reconstruction of past peatland area based on transfer functions (paper II) reveals that 70%of the peatlands of Sumatra and Kalimantan only formed during the past 4000 years.Moreover, this new transfer function approach shows that the common basal dates approach overestimated the extent of peatlands in the past. This method, in general, leads to higher rates of reconstructed cumulative peat carbon uptake for the past. By combining reconstructed peatland areas and mean rates of carbon accumulation over millennial timescales from each peatland type the carbon uptake of all peatlands from Sumatra and Kalimantan could be quantified for the past 15,000 years (paper II). Carbon uptake remained below 1 Teragram (Tg) C yr-1 from 15,000-5000 cal BP because the total area of peatlands was less than 30,000 km2. Rapid peatland expansion driven by the lowering of sea-level over the past 5000 years increased carbon uptake on Sumatra and Kalimantan to over 7 Tg C yr-1 and resulted in an exponential growth of the regional peat-carbon reservoir to a size of over 20 Pg C. SoutheastAsian peatlands therefore had no significant role in the Late Pleistocene and Early Holocene global carbon cycle. However, because of their rapid expansion after 5000 cal BP by over 100,000 km2 the peatlands of SoutheastAsia became a globally important carbon sink during the Late Holocene and likely caused an atmospheric CO2 drawdown of 1-2 ppm (paper II). This previously unrecognized biospheric carbon sink partly compensated for contemporaneous terrestrial carbon losses associated with the desertification of Northern Africa. The mechanisms that enable high rates of carbon accumulation of coastal peatlands were explored in a peat core study presented in paper III. Here the use of a new coring technique for the tropics and the application of noninvasive geophysical measurements were employed to derive a high-resolution record of carbon accumulation rates. This study provides the first description of peatland pools for SoutheastAsia, which form as tip-up pools from falling trees such as Shorea albida. Based on a pollen and macrofossil record a fossil tip-up pool could be identified in the core and an associated carbon accumulation rate of 100 to over 900 g C m-2 yr-1 determined. Thus tip-up pools function as local hot spots for carbon accumulation, fundamentally different from northern hemisphere peatland pools, which act as net-carbon sources. From a time-series of aerial photographs the rate of tree fall and thus pool formation was determined at 0.4 tree ha-1 yr-1 (paper III).Asimulation model indicates that up to 60%of the peat deposited in peat domes of Borneo is derived from filled up fossil pools – changing the paradigm that Southeast Asian peatlands mainly form from belowground biomass and providing an explanation for the rapid carbon accumulation of these ecosystems. The climate impact of peatlands is, however, not only related to their capacity to rapidly store carbon, because peatlands also release the strong greenhouse gas methane – a by-product of anaerobic decomposition.Ametaanalysis of methane emission data from SoutheastAsian peatlands (paper IV) shows that their average annual methane release of 3 g CH4 m-2 yr-1 is lower than the average annual release of ~9 g CH4 m-2 yr-1 from northern peatlands, although the higher tropical soil temperatures should lead to significantly higher emissions. The limited degree of anaerobic decay is explained by the recalcitrance of the deposited biomass, which contains high amounts of lignin and tannin, providing another explanation for rapid carbon accumulation. Low anaerobic decomposition together with high rates of carbon accumulation imply that limits to vertical peat bog growth in SoutheastAsia are not set by cumulative anaerobic decay as in northern raised bogs. Instead peat bog growth is limited by aerobic decomposition related to water-table lowering as shown by a derived linear relationship between the amount of released CO2 from aerobic peat decomposition and the mean annual depth of the peatland water-table (paper IV). The climatic effect of Southeast Asian peatlands was determined by the global warming potential (GWP) method, which compares carbon uptake with methane emissions in terms of CO2-equivalents. The low methane emissions and high carbon accumulation rates of coastal peatlands result in a net annual uptake of 1340 kg CO2- equiv. ha-1 yr-1 over a 100 year GWP time-horizon. Under natural conditions coastal Southeast peatlands exert a significant net cooling effect on the global climate in contrast to northern peatlands, which have a warming effect or act climatic neutral on this time frame. It can be concluded that the tropical peatlands of SoutheastAsia are the strongest carbon sinks among all peatlands globally with a notable influence on the Earth’s radiative budget. However, today an estimated 90,000 km2 of peatlands in SoutheastAsia is drained for agriculture (e.g. oil palm plantations) and deforestation. These drained peatlands release annually over 140 Tg C yr-1 from aerobic peat 141 decomposition. Drainage also facilitates the regular spread of peat fires in this region, which on average release around 75 Tg C yr-1. Ongoing total carbon losses (~220 Tg C yr-1) exceed the natural carbon uptake by a factor of 25 and demonstrate that the entire SoutheastAsian peatland region has recently switched from a globally important carbon sink to a globally significant source of atmospheric CO2 (paper II, IV).
Die vorliegende Arbeit behandelt die Gewässernetzentwicklung im Bereich der Pommerschen Haupteisrandlage (W2), des eng benachbarten Frühpommerschen Vorstoßes (W2max) und der südlich angrenzenden Sanderflächen in einem Ausschnitt, der ungefähr zwischen Krakow, Goldberg und Malchow im mittleren Mecklenburg gelegen ist. Ziel der Untersuchungen ist die Verknüpfung geomorphologischer, bodenkundlicher, paläobotanischer, paläolimnologischer, archäologischer und historischer Befunde zur paläohydrographischen Rekonstruktion der Gewässer seit dem Spätpleistozän, eines etwa 14.000 Jahre umfassenden Zeitraums. Die hierbei präferierte multidisziplinäre Bearbeitungsweise limnischer Sedimentsequenzen aus Seebohrungen in Verbindung mit landseitigen bodenkundlich–geomorphologischen Kartierungen stellt (noch immer) ein Novum in der Gewässerforschung Mecklenburg-Vorpommerns dar und liefert wichtige Ergänzungen zu Modellvorstellungen der Gewässerentwicklung. Thematische Schwerpunkte werden für die verknüpfte, spätpleistozäne Becken– und Durchbruchstalentwicklung, die fortan archivierte limnisch–telmatische Sedimentationsgeschichte, die Wasserstandsentwicklung und die Wechselwirkung Mensch und Gewässer gesetzt. Zugleich erlauben die bodenkundlichen Arbeiten im Gewässerumfeld Aussagen zur Bodengenese und Landnutzungsgeschichte besonders innerhalb der Nossentiner–Schwinzer Heide. Im Zuge der palynologischen Bearbeitung der Seesedimente durch Dritte liegt desweiteren eine lückenlose Vegetationsgeschichte des Untersuchungsgebietes seit dem Allerød vor, die ebenso wertvolle Ableitungen zur regionalen Siedlungs- und Landnutzungsgeschichte erlaubt. Diatomeen–basierte paläolimnologische Aussagen ebenfalls Dritter fokussieren auf die postglaziale Trophie– und die Wasserstandsentwicklung der untersuchten Seen.
Die vorliegende Arbeit behandelt die holozäne Küstenentwicklung im Raum Darss-Zingst-Hiddensee, die eng an die Interaktion von eustatischen Meeresspiegelschwankungen, neotektonischen Bewegungen der Erdkruste und dem zugeführten Sedimentvolumen gebunden ist. Es sind mehrere Ziele der Untersuchungen zu nennen: Zunächst relevant ist die Kartierung der holozänen Sedimentabfolge und der liegenden pleistozänen Deckschichten im Untersuchungsgebiet, das neben den Nehrungen auch das angrenzende Seegebiet der Ostsee und die rückseitigen Lagunen umfasst. Anschließend ist die Modellierung der Transgressionsbasisfläche notwendig, um das im Holozän unter marinen Bedingungen umgelagerte Sedimentvolumen abschätzen zu können. Eine Kernfragestellung bildet die Sedimentbilanz. Vor allem für das Teilgebiet Zingst mit östlich angrenzendem Windwatt und Barriere-Inseln sind die Sedimentquellen, die zur Aufschüttung dieses Nehrungskörpers geführt haben, unklar. Die potentielle Materialbereitstellung umliegender Kliffe (Fischland, Altdarss) ist im Verhältnis zum Nehrungsvolumen relativ gering. In Kombination mit geochronologischen Untersuchungen der Sedimentsequenz ergeben sich im Gesamtraum Schlussfolgerungen über die Ablagerungsdynamik, die zur Ausbildung der gegenwärtigen Küstenlandschaft geführt hat. Anhand der Befunde wurde ein paläogeographisches Modell der Küstenentwicklung für das Gebiet abgeleitet. Diese Ergebnisse bilden die Grundlage zur Entwicklung zukünftiger Szenarien der Küstengenese mit Hilfe von morphodynamischen Prozessmodellen, die weiterführende Aufgabenstellungen bieten. Aus Sichtweise des Küstenschutzes und vor dem Hintergrund beschleunigter Anstiegsprognosen des Meeresspiegels sind die gewonnenen Erkenntnisse von hoher Bedeutung.
Understanding the interaction between climate variability and ice sheet behavior is critical due to scenarios of future climate warming and the consequent contribution of Greenland ice sheet melting to sea-level rise and its potential to influence thermohaline circulation. This thesis investigates the role of ocean forcing by the West Greenland Current (WGC) on the dynamics of West Greenland ice sheet behavior, with focus on Jakobshavn Isbræ, in the Disko Bugt area of central West Greenland. High-resolution sediment cores, obtained during a cruise of the RV ‘Maria S. Merian’ in 2007, provide a long-term Holocene perspective on climate variability off West Greenland. These records cover the last 8000 years with increasing resolution through to periods of historical and instrumental data series. Paleoenvironmental reconstructions, based on the calcareous and agglutinated benthic foraminiferal assemblage, reveal significant variations in the water mass properties (e.g. temperature and salinity) of the WGC. From 8 to 6 cal. ka BP, a relatively warm WGC enhances meltwater production (ice retreat) in Disko Bugt. Holocene ‘thermal optimum-like’ conditions prevailed from 5.5 to 3.5 cal. ka BP, associated with minimum ice sheet extent in eastern Disko Bugt. Long-term cooling of oceanographic conditions is recognized from c. 3.5 cal. ka BP towards the present day. Superimposed on this millennial scale cooling trend, centennial scale variability within the WGC is reconstructed: i) the 2.7 cal. ka BP ‘cooling event’; ii) the Roman Warm Period; iii) the Medieval Climate Anomaly; and iv) the Little Ice Age. Over the past 100 years, oceanographic conditions remain relatively cool and multidecadal variability in the WGC’s ocean temperatures show close correlation with the ice marg in position of Jakobshavn Isbræ and phases of the Atlantic Multi-decadal Oscillation (AMO). Cold (warm) phases correlate with stabilization/re-advance (retreat) of Jakobshavn Isbræ and a negative (high) index of the AMO. It has been demonstrated that variations in ocean temperature are an important factor that influence ice sheet behavior on a range of times scales, underlining the close coupling of ice-ocean interactions during the Holocene. Warmer ocean temperatures influence the stability of marine terminating ice sheets and glaciers, causing basal melting and glacier acceleration, whereas ocean cooling supports stabilization and advance of ice margin.
The pollen record is a powerful proxy to reconstruct past terrestrial vegetation, but quantifying plant abundances is strongly limited because plants produce pollen in different amounts and pollen is dispersed differently. Further complications arise from the use of percentage data. Finally, a pollen grain deposited at a site may have arrived from proximate or distant sources, which implies that a single pollen sample may reflect very different vegetation scenarios. Present thesis suggests improving quantitative reconstructions of past vegetation by refined calibration of the pollen-vegetation relationship (paper I) and application of the downscaling approach (papers II-IV). Paper I primarily addresses the questions of pollen production and dispersal by calibrating the pollen-vegetation relationship. Data analysis employs the common extended R-value (ERV) approach and a new data-model comparison method, which appears more suitable than the ERV approach. For the first time PPEs have been calculated using three contrasting pollen dispersal options, including a Lagrangian stochastic (LS) model. The study proves that the underlying pollen dispersal model is a crucial parameter in PPE calculations and that the calculations with the LS model produce more reliable and realistic PPEs. Papers II to IV address quantitative reconstructions of past vegetation. Using the newly developed downscaling approach, the three studies explore fine scaled vegetation patterns in NE Germany during the Late Glacial and early Holocene. The main assumption of the downscaling approach is that the present day pattern of abiotic site conditions (e.g. the pattern of soil substrates) existed, at least to a large extend, also during the study periods. The basic principle of the approach is to test, whether pollen deposition in sites across a landscape is correlated to that site pattern. The first application of the approach (paper II) has shown a close correlation between PINUS pollen percentages and the distance weighted abundance of sandy soils and between BETULA pollen percentages and the distance weighted abundance of morainic till during the Allerød period, indicating that pine and birch formed rather separate stands on either substrate type. The cooling of the Younger Dryas induced significant changes in the vegetation of NE Germany. By combining pollen percentage and pollen accumulation rate data paper III identified a sharp vegetation boundary between the Mecklenburg and Brandenburg area at about 53 °N. The downscaling approach, here used with pollen accumulation rate data, suggests that in the North small tree stands could only exist in sheltered positions. The sharp vegetation boundary is possibly related to a climatic gradient and the southern permafrost limit, which itself may result from the formation of sea ice on the North Atlantic north of 53°N during winter. The warming of the Holocene again allowed the expansion of forests in the study area. Paper IV uses high resolution pollen (accumulation rate) data to study the successive forest formation, including the immigration of hazel, and explores vegetation patterns and composition during these successive stages using the extended downscaling approach. This approach addresses the problems related to differential pollen production, dispersal and the use of percentage data by applying simulations. It reveals that initially pine and birch established, as during the Allerød period, in largely separate stands with pine dominating on sandy soils and birch dominating on fine grained soils. Also open rich vegetation persisted, possibly due to seasonal drought, mainly on fine grained soils. Hazel later mainly spread on sites that received additional wetness from ground or surface water; it did not enter pine dominated forests on well drained sandy soils. Overall, the early Holocene vegetation of the study area was sharply differentiated by soil humidity and fertility. To conclude, present thesis has revealed vegetation patterns and species site preferences in NE Germany during three periods of the Lateglacial and early Holocene. The results improve our understanding of vegetation history in northern Central Europe, specifically for periods of rapid climate change. The approaches applied are flexible with respect to the type and quality of pollen data used and may be implemented using standard software packages.
The Black Sea experienced fundamental environmental changes during the last glacial-interglacial transitions. During the last 670,000 years, the Black Sea was at least twelve times connected to Mediterranean Sea, received saltwater via the Bosporus strait, and evolved to a brackish anoxic water body. A lowered global sea level during glacials caused isolation of the basin from the open ocean, and the Black Sea became limnic and well-oxygenated. The last glacial-interglacial history of the Black Sea is relatively well understood and demonstrates the high sensitivity of this basin to global climate and environmental changes. Previous studies particularly focussed on the evolution during the last glacial with meltwater pulses, warming during the glacial-interglacial transition, and the development from a ventilated lake to the present euxinic/brackish water body. Apart from the interglacial warming, the Black Sea sediments clearly recorded short-term abrupt temperature changes associated with cooling during Heinrich events and the Younger Dryas as well the Bølling-Allerød warming, which occurred over the northern hemisphere. However, our knowledge about the Black Sea history before 40,000 BP is comparatively poor even though crucial for understanding hemisphere-wide atmospheric teleconnection patterns and climate mechanisms during older glacials and interglacials. A multiproxy approach has been applied on three gravity cores and surface sediment from the southeastern Black Sea comprising ostracod geochemistry (Mg/Ca, Sr/Ca, U/Ca, 87Sr/86Sr), major and trace elements (Al, Ca, Fe, K, Ti, Mo, Re, Sr, W, Zr) and organic biomarkers (n-alkanes, alkenones, UK’37-palaeotemperatures, glycerol dialkyl glycerol tetraethers, TEX86-palaeotemperatures, BIT-index). The cores cover the last 134,000 a and provide new findings concerning the last and penultimate glacial-interglacial transitions (12,000- 0 a BP; 134,000-120,000 a BP) as well as the abrupt climate changes during the last glacial period (64,000-20,000 a BP). The major topics of this work are i) the penultimate glacial-interglacial transition (Saalian-Eemian), ii) the environmental conditions in the Black Sea “Lake” during abrupt climate oscillations of the last glacial period, iii) and the comparison of the redox evolution during Eemian and Holocene sapropel formation. Two meltwater pulses caused a pronounced freshening of the Black Sea “Lake” during the ending penultimate glacial, which originated from the melting Fennoscandian Ice Sheet. Due to unusually high radiogenic Sr-isotope signatures of benthic ostracods, a potential Himalayan source communicated via the Caspian Sea is also likely. During the glacial-interglacial transition the temperatures in the Black Sea increased from 9°C to 17°C and the associated global sea-level rise allowed the reconnection between the Mediterranean and Black Seas around 128,000 a BP. Eemian sapropel formation started shortly after the intrusion of saltwater and the water body became gradually euxinic. In comparison with the Holocene sapropel, the Eemian proxy records imply warmer and stronger euxinic conditions and distinctly higher enrichments of redox-sensitive trace elements like e.g. Mo, Re, and W. Because the seawater forms the ultimate source for several trace metals, these enrichments were most likely favoured by the higher salinity due to a ca. 10 m higher sea level and enhanced Mediterranean Sea - Black Sea water exchange. Based on biomarker analyses, lake surface temperatures could be calculated for the first time for the period between 64,000 and 20,000 a BP, which includes the Marine Isotope Stage (MIS) 3. Abrupt stadial/interstadial temperature changes with amplitudes of up to 4°C in the Black Sea “Lake” clearly resemble the Greenland Dansgaard-Oeschger pattern. However, an exceptional cooling during the so-called Heinrich events is not evident from our cores. This finding agrees with modelling results proposing a deeper penetration of regular Dansgaard-Oeschger cycles into the Eurasian continent when compared with the Heinrich events. During the warm and more humid interstadials, the Black Sea “Lake” became fresher and more productive and the water level probably increased. During the colder and more arid stadials the freshwater supply was decreased and productivity was low. Aridity and stronger westerly winds favoured the input of aeolian transported detritus. The long-term pattern from 64,000 to 20,000 a BP demonstrates a strong influence of orbital-driven changes in the Eurasian ice volume and associated atmospheric circulation patterns over the Black Sea region. The present multi-proxy study demonstrates that the sediments from the SE Black Sea clearly record not only orbital- but also millennial-scale climate and environmental changes and thus represent an important continental archive for climate change bridging the North Atlantic-Eurasian corridor.