TY  - JOUR
A1  - Bryant, Seth
A1  - Davies, Evan
A1  - Sol, David
A1  - Davis, Sandy
T1  - The progression of flood risk in southern Alberta since the 2013 flood
JF  - Journal of flood risk management
N2  - After a century of semi-restricted floodplain development, Southern Alberta, Canada, was struck by the devastating 2013 Flood. Aging infrastructure and limited property-level floodproofing likely contributed to the $4-6 billion (CAD) losses. Following this catastrophe, Alberta has seen a revival in flood management, largely focused on structural protections. However, concurrent with the recent structural work was a 100,000+ increase in Calgary's population in the 5 years following the flood, leading to further densification of high-hazard areas. This study implements the novel Stochastic Object-based Flood damage Dynamic Assessment (SOFDA) model framework to quantify the progression of the direct-damage flood risk in a mature urban neighborhood after the 2013 Flood. Five years of remote-sensing data, property assessment records, and inundation simulations following the flood are used to construct the model. Results show that in these 5 years, vulnerability trends (like densification) have increased flood risk by 4%; however, recent structural mitigation projects have reduced overall flood risk by 47% for this case study. These results demonstrate that the flood management revival in Southern Alberta has largely been successful at reducing flood risk; however, the gains are under threat from continued development and densification absent additional floodproofing regulations.
KW  - Calgary
KW  - depth-damage functions
KW  - expected annual damages
KW  - flood risk
KW  - model
KW  - property level protection measures
KW  - risk analysis
KW  - risk dynamics
Y1  - 2022
U6  - https://doi.org/10.1111/jfr3.12811
SN  - 1753-318X
VL  - 15
IS  - 3
PB  - Wiley-Blackwell
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Ramachandran, Srikanthan
A1  - Rupakheti, Maheswar
A1  - Lawrence, Mark
T1  - Aerosol-induced atmospheric heating rate decreases over South and East Asia as a result of changing content and composition
JF  - Scientific reports
N2  - Aerosol emissions from human activities are extensive and changing rapidly over Asia. Model simulations and satellite observations indicate a dipole pattern in aerosol emissions and loading between South Asia and East Asia, two of the most heavily polluted regions of the world. We examine the previously unexplored diverging trends in the existing dipole pattern of aerosols between East and South Asia using the high quality, two-decade long ground-based time series of observations of aerosol properties from the Aerosol Robotic Network (AERONET), from satellites (Moderate Resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring Instrument (OMI)), and from model simulations (Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). The data cover the period since 2001 for Kanpur (South Asia) and Beijing (East Asia), two locations taken as being broadly representative of the respective regions. Since 2010 a dipole in aerosol optical depth (AOD) is maintained, but the trend is reversed-the decrease in AOD over Beijing (East Asia) is rapid since 2010, being 17% less in current decade compared to first decade of twenty-first century, while the AOD over South Asia increased by 12% during the same period. Furthermore, we find that the aerosol composition is also changing over time. The single scattering albedo (SSA), a measure of aerosol's absorption capacity and related to aerosol composition, is slightly higher over Beijing than Kanpur, and has increased from 0.91 in 2002 to 0.93 in 2017 over Beijing and from 0.89 to 0.92 during the same period over Kanpur, confirming that aerosols in this region have on an average become more scattering in nature. These changes have led to a notable decrease in aerosol-induced atmospheric heating rate (HR) over both regions between the two decades, decreasing considerably more over East Asia (- 31%) than over South Asia (- 9%). The annual mean HR is lower now, it is still large (>= 0.6 K per day), which has significant climate implications. The seasonal trends in AOD, SSA and HR are more pronounced than their respective annual trends over both regions. The seasonal trends are caused mainly by the increase/decrease in anthropogenic aerosol emissions (sulfate, black carbon and organic carbon) while the natural aerosols (dust and sea salt) did not change significantly over South and East Asia during the last two decades. The MERRA-2 model is able to simulate the observed trends in AODs well but not the magnitude, while it also did not simulate the SSA values or trends well. These robust findings based on observations of key aerosol parameters and previously unrecognized diverging trends over South and East Asia need to be accounted for in current state-of-the-art climate models to ensure accurate quantification of the complex and evolving impact of aerosols on the regional climate over Asia.
Y1  - 2020
U6  - https://doi.org/10.1038/s41598-020-76936-z
SN  - 2045-2322
VL  - 10
IS  - 1
PB  - Macmillan Publishers Limited, part of Springer Nature
CY  - [London]
ER  - 
TY  - JOUR
A1  - Rözer, Viktor
A1  - Kreibich, Heidi
A1  - Schröter, Kai
A1  - Müller, Meike
A1  - Sairam, Nivedita
A1  - Doss-Gollin, James
A1  - Lall, Upmanu
A1  - Merz, Bruno
T1  - Probabilistic Models Significantly Reduce Uncertainty in Hurricane Harvey Pluvial Flood Loss Estimates
JF  - Earths future
N2  - Pluvial flood risk is mostly excluded in urban flood risk assessment. However, the risk of pluvial flooding is a growing challenge with a projected increase of extreme rainstorms compounding with an ongoing global urbanization. Considered as a flood type with minimal impacts when rainfall rates exceed the capacity of urban drainage systems, the aftermath of rainfall-triggered flooding during Hurricane Harvey and other events show the urgent need to assess the risk of pluvial flooding. Due to the local extent and small-scale variations, the quantification of pluvial flood risk requires risk assessments on high spatial resolutions. While flood hazard and exposure information is becoming increasingly accurate, the estimation of losses is still a poorly understood component of pluvial flood risk quantification. We use a new probabilistic multivariable modeling approach to estimate pluvial flood losses of individual buildings, explicitly accounting for the associated uncertainties. Except for the water depth as the common most important predictor, we identified the drivers for having loss or not and for the degree of loss to be different. Applying this approach to estimate and validate building structure losses during Hurricane Harvey using a property level data set, we find that the reliability and dispersion of predictive loss distributions vary widely depending on the model and aggregation level of property level loss estimates. Our results show that the use of multivariable zero-inflated beta models reduce the 90% prediction intervalsfor Hurricane Harvey building structure loss estimates on average by 78% (totalling U.S.$3.8 billion) compared to commonly used models.
KW  - pluvial flooding
KW  - loss modeling
KW  - urban flooding
KW  - probabilistic
KW  - Hurricane Harvey
KW  - climate change adaptation
Y1  - 2019
U6  - https://doi.org/10.1029/2018EF001074
SN  - 2328-4277
VL  - 7
IS  - 4
SP  - 384
EP  - 394
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Sairam, Nivedita
A1  - Schröter, Kai
A1  - Lüdtke, Stefan
A1  - Merz, Bruno
A1  - Kreibich, Heidi
T1  - Quantifying Flood Vulnerability Reduction via Private Precaution
JF  - Earth future
N2  - Private precaution is an important component in contemporary flood risk management and climate adaptation. However, quantitative knowledge about vulnerability reduction via private precautionary measures is scarce and their effects are hardly considered in loss modeling and risk assessments. However, this is a prerequisite to enable temporally dynamic flood damage and risk modeling, and thus the evaluation of risk management and adaptation strategies. To quantify the average reduction in vulnerability of residential buildings via private precaution empirical vulnerability data (n = 948) is used. Households with and without precautionary measures undertaken before the flood event are classified into treatment and nontreatment groups and matched. Postmatching regression is used to quantify the treatment effect. Additionally, we test state-of-the-art flood loss models regarding their capability to capture this difference in vulnerability. The estimated average treatment effect of implementing private precaution is between 11 and 15 thousand EUR per household, confirming the significant effectiveness of private precautionary measures in reducing flood vulnerability. From all tested flood loss models, the expert Bayesian network-based model BN-FLEMOps and the rule-based loss model FLEMOps perform best in capturing the difference in vulnerability due to private precaution. Thus, the use of such loss models is suggested for flood risk assessments to effectively support evaluations and decision making for adaptable flood risk management.
KW  - flood loss
KW  - average treatment effect
KW  - matching methods
KW  - loss models
KW  - risk analysis
KW  - adaptation
Y1  - 2019
U6  - https://doi.org/10.1029/2018EF000994
SN  - 2328-4277
VL  - 7
IS  - 3
SP  - 235
EP  - 249
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Dietze, Michael
A1  - Bell, Rainer
A1  - Öztürk, Ugur
A1  - Cook, Kristen L.
A1  - Andermann, Christoff
A1  - Beer, Alexander R.
A1  - Damm, Bodo
A1  - Lucia, Ana
A1  - Fauer, Felix S.
A1  - Nissen, Katrin M.
A1  - Sieg, Tobias
A1  - Thieken, Annegret H.
T1  - More than heavy rain turning into fast-flowing water - a landscape perspective on the 2021 Eifel floods
JF  - Natural hazards and earth system sciences
N2  - Rapidly evolving floods are rare but powerful drivers of landscape reorganisation that have severe and long-lasting impacts on both the functions of a landscape's subsystems and the affected society. The July 2021 flood that particularly hit several river catchments of the Eifel region in western Germany and Belgium was a drastic example. While media and scientists highlighted the meteorological and hydrological aspects of this flood, it was not just the rising water levels in the main valleys that posed a hazard, caused damage, and drove environmental reorganisation. Instead, the concurrent coupling of landscape elements and the wood, sediment, and debris carried by the fast-flowing water made this flood so devastating and difficult to predict. Because more intense floods are able to interact with more landscape components, they at times reveal rare non-linear feedbacks, which may be hidden during smaller events due to their high thresholds of initiation. Here, we briefly review the boundary conditions of the 14-15 July 2021 flood and discuss the emerging features that made this event different from previous floods. We identify hillslope processes, aspects of debris mobilisation, the legacy of sustained human land use, and emerging process connections and feedbacks as critical non-hydrological dimensions of the flood. With this landscape scale perspective, we develop requirements for improved future event anticipation, mitigation, and fundamental system understanding.
Y1  - 2022
U6  - https://doi.org/10.5194/nhess-22-1845-2022
SN  - 1561-8633
SN  - 1684-9981
VL  - 22
IS  - 6
SP  - 1845
EP  - 1856
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Herzschuh, Ulrike
A1  - Cao, Xianyong
A1  - Laepple, Thomas
A1  - Dallmeyer, Anne
A1  - Telford, Richard J.
A1  - Ni, Jian
A1  - Chen, Fahu
A1  - Kong, Zhaochen
A1  - Liu, Guangxiu
A1  - Liu, Kam-Biu
A1  - Liu, Xingqi
A1  - Stebich, Martina
A1  - Tang, Lingyu
A1  - Tian, Fang
A1  - Wang, Yongbo
A1  - Wischnewski, Juliane
A1  - Xu, Qinghai
A1  - Yan, Shun
A1  - Yang, Zhenjing
A1  - Yu, Ge
A1  - Zhang, Yun
A1  - Zhao, Yan
A1  - Zheng, Zhuo
T1  - Position and orientation of the westerly jet determined Holocene rainfall patterns in China
JF  - Nature Communications
N2  - Proxy-based reconstructions and modeling of Holocene spatiotemporal precipitation patterns for China and Mongolia have hitherto yielded contradictory results indicating that the basic mechanisms behind the East Asian Summer Monsoon and its interaction with the westerly jet stream remain poorly understood. We present quantitative reconstructions of Holocene precipitation derived from 101 fossil pollen records and analyse them with the help of a minimal empirical model. We show that the westerly jet-stream axis shifted gradually southward and became less tilted since the middle Holocene. This was tracked by the summer monsoon rain band resulting in an early-Holocene precipitation maximum over most of western China, a mid-Holocene maximum in north-central and northeastern China, and a late-Holocene maximum in southeastern China. Our results suggest that a correct simulation of the orientation and position of the westerly jet stream is crucial to the reliable prediction of precipitation patterns in China and Mongolia.
Y1  - 2019
U6  - https://doi.org/10.1038/s41467-019-09866-8
SN  - 2041-1723
VL  - 10
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Steirou, Eva
A1  - Gerlitz, Lars
A1  - Apel, Heiko
A1  - Sun, Xun
A1  - Merz, Bruno
T1  - Climate influences on flood probabilities across Europe
JF  - Hydrology and earth system sciences : HESS
N2  - The link between streamflow extremes and climatology has been widely studied in recent decades. However, a study investigating the effect of large-scale circulation variations on the distribution of seasonal discharge extremes at the European level is missing. Here we fit a climate-informed generalized extreme value (GEV) distribution to about 600 streamflow records in Europe for each of the standard seasons, i.e., to winter, spring, summer and autumn maxima, and compare it with the classical GEV distribution with parameters invariant in time. The study adopts a Bayesian framework and covers the period 1950 to 2016. Five indices with proven influence on the European climate are examined independently as covariates, namely the North Atlantic Oscillation (NAO), the east Atlantic pattern (EA), the east Atlantic-western Russian pattern (EA/WR), the Scandinavia pattern (SCA) and the polar-Eurasian pattern (POL). It is found that for a high percentage of stations the climate-informed model is preferred to the classical model. Particularly for NAO during winter, a strong influence on streamflow extremes is detected for large parts of Europe (preferred to the classical GEV distribution for 46% of the stations). Climate-informed fits are characterized by spatial coherence and form patterns that resemble relations between the climate indices and seasonal precipitation, suggesting a prominent role of the considered circulation modes for flood generation. For certain regions, such as northwestern Scandinavia and the British Isles, yearly variations of the mean seasonal climate indices result in considerably different extreme value distributions and thus in highly different flood estimates for individual years that can also persist for longer time periods.
Y1  - 2019
U6  - https://doi.org/10.5194/hess-23-1305-2019
SN  - 1027-5606
SN  - 1607-7938
VL  - 23
IS  - 3
SP  - 1305
EP  - 1322
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Dietze, Elisabeth
A1  - Mangelsdorf, Kai
A1  - Andreev, Andrei
A1  - Karger, Cornelia
A1  - Schreuder, Laura T.
A1  - Hopmans, Ellen C.
A1  - Rach, Oliver
A1  - Sachse, Dirk
A1  - Wennrich, Volker
A1  - Herzschuh, Ulrike
T1  - Relationships between low-temperature fires, climate and vegetation during three late glacials and interglacials of the last 430 kyr in northeastern Siberia reconstructed from monosaccharide anhydrides in Lake El’gygytgyn sediments
JF  - Climate of the Past
N2  - Landscapes in high northern latitudes are assumed to be highly sensitive to future global change, but the rates and long-term trajectories of changes are rather uncertain. In the boreal zone, fires are an important factor in climate-vegetation interactions and biogeochemical cycles. Fire regimes are characterized by small, frequent, low-intensity fires within summergreen boreal forests dominated by larch, whereas evergreen boreal forests dominated by spruce and pine burn large areas less frequently but at higher intensities. Here, we explore the potential of the monosaccharide anhydrides (MA) levoglucosan, mannosan and galactosan to serve as proxies of low-intensity biomass burning in glacial-to-interglacial lake sediments from the high northern latitudes. We use sediments from Lake El'gygytgyn (cores PG 1351 and ICDP 5011-1), located in the far north-east of Russia, and study glacial and interglacial samples of the last 430 kyr (marine isotope stages 5e, 6, 7e, 8, 11c and 12) that had different climate and biome configurations. Combined with pollen and non-pollen palynomorph records from the same samples, we assess how far the modern relationships between fire, climate and vegetation persisted during the past, on orbital to centennial timescales. We find that MAs attached to particulates were well-preserved in up to 430 kyr old sediments with higher influxes from low-intensity biomass burning in interglacials compared to glacials. MA influxes significantly increase when summergreen boreal forest spreads closer to the lake, whereas they decrease when tundra-steppe environments and, especially, Sphagnum peatlands spread. This suggests that low-temperature fires are a typical characteristic of Siberian larch forests also on long timescales. The results also suggest that low-intensity fires would be reduced by vegetation shifts towards very dry environments due to reduced biomass availability, as well as by shifts towards peatlands, which limits fuel dryness. In addition, we observed very low MA ratios, which we interpret as high contributions of galactosan and mannosan from biomass sources other than those currently monitored, such as the moss-lichen mats in the understorey of the summergreen boreal forest. Overall, sedimentary MAs can provide a powerful proxy for fire regime reconstructions and extend our knowledge of long-term natural fire-climate-vegetation feedbacks in the high northern latitudes.
KW  - molecular tracers
KW  - organic aerosols
KW  - emission factors
KW  - carbonaceous aerosols
KW  - pollen records
KW  - core PG1351
KW  - biomass
KW  - holocene
KW  - levoglucosan
KW  - charcoal
Y1  - 2020
U6  - https://doi.org/10.5194/cp-16-799-2020
SN  - 1814-9332
SN  - 1814-9324
VL  - 16
IS  - 2
SP  - 788
EP  - 818
PB  - Copernicus Publications
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Miesner, Timon
A1  - Herzschuh, Ulrike
A1  - Pestryakova, Luidmila Agafyevna
A1  - Wieczorek, Mareike
A1  - Zakharov, Evgenii S.
A1  - Kolmogorov, Alexei I.
A1  - Davydova, Paraskovya V.
A1  - Kruse, Stefan
T1  - Forest structure and individual tree inventories of northeastern Siberia along climatic gradients
JF  - Earth system science data : ESSD
N2  - We compile a data set of forest surveys from expeditions to the northeast of the Russian Federation, in Krasnoyarsk Krai, the Republic of Sakha (Yakutia), and the Chukotka Autonomous Okrug (59-73 degrees N, 97-169 degrees E), performed between the years 2011 and 2021. The region is characterized by permafrost soils and forests dominated by larch (Larix gmelinii Rupr. and Larix cajanderi Mayr). 
Our data set consists of a plot database describing 226 georeferenced vegetation survey plots and a tree database with information about all the trees on these plots. The tree database, consisting of two tables with the same column names, contains information on the height, species, and vitality of 40 289 trees. A subset of the trees was subject to a more detailed inventory, which recorded the stem diameter at base and at breast height, crown diameter, and height of the beginning of the crown.
We recorded heights up to 28.5 m (median 2.5 m) and stand densities up to 120 000 trees per hectare (median 1197 ha(-1)), with both values tending to be higher in the more southerly areas. Observed taxa include Larix Mill., Pinus L., Picea A. Dietr., Abies Mill., Salix L., Betula L., Populus L., Alnus Mill., and Ulmus L. 
In this study, we present the forest inventory data aggregated per plot. Additionally, we connect the data with different remote sensing data products to find out how accurately forest structure can be predicted from such products. Allometries were calculated to obtain the diameter from height measurements for every species group. For Larix, the most frequent of 10 species groups, allometries depended also on the stand density, as denser stands are characterized by thinner trees, relative to height. The remote sensing products used to compare against the inventory data include climate, forest biomass, canopy height, and forest loss or disturbance. We find that the forest metrics measured in the field can only be reconstructed from the remote sensing data to a limited extent, as they depend on local properties. This illustrates the need for ground inventories like those data we present here.
The data can be used for studying the forest structure of northeastern Siberia and for the calibration and validation of remotely sensed data.
Y1  - 2022
U6  - https://doi.org/10.5194/essd-14-5695-2022
SN  - 1866-3508
SN  - 1866-3516
VL  - 14
IS  - 12
SP  - 5695
EP  - 5716
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Kruse, Stefan
A1  - Stünzi, Simone Maria
A1  - Boike, Julia
A1  - Langer, Moritz
A1  - Gloy, Josias
A1  - Herzschuh, Ulrike
T1  - Novel coupled permafrost-forest model (LAVESI-CryoGrid v1.0) revealing the interplay between permafrost, vegetation, and climate across eastern Siberia
JF  - Geoscientific model development : GMD ; an interactive open access journal of the European Geosciences Union
N2  - Boreal forests of Siberia play a relevant role in the global carbon cycle. However, global warming threatens the existence of summergreen larch-dominated ecosystems, likely enabling a transition to evergreen tree taxa with deeper active layers. Complex permafrost-vegetation interactions make it uncertain whether these ecosystems could develop into a carbon source rather than continuing atmospheric carbon sequestration under global warming. Consequently, shedding light on the role of current and future active layer dynamics and the feedbacks with the apparent tree species is crucial to predict boreal forest transition dynamics and thus for aboveground forest biomass and carbon stock developments. Hence, we established a coupled model version amalgamating a one-dimensional permafrost multilayer forest land-surface model (CryoGrid) with LAVESI, an individual-based and spatially explicit forest model for larch species (Larix Mill.), extended for this study by including other relevant Siberian forest species and explicit terrain. <br /> Following parameterization, we ran simulations with the coupled version to the near future to 2030 with a mild climate-warming scenario. We focus on three regions covering a gradient of summergreen forests in the east at Spasskaya Pad, mixed summergreen-evergreen forests close to Nyurba, and the warmest area at Lake Khamra in the southeast of Yakutia, Russia. Coupled simulations were run with the newly implemented boreal forest species and compared to runs allowing only one species at a time, as well as to simulations using just LAVESI. Results reveal that the coupled version corrects for overestimation of active layer thickness (ALT) and soil moisture, and large differences in established forests are simulated. We conclude that the coupled version can simulate the complex environment of eastern Siberia by reproducing vegetation patterns, making it an excellent tool to disentangle processes driving boreal forest dynamics.
Y1  - 2022
U6  - https://doi.org/10.5194/gmd-15-2395-2022
SN  - 1991-959X
SN  - 1991-9603
VL  - 15
IS  - 6
SP  - 2395
EP  - 2422
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Radosavljevic, Boris
A1  - Lantuit, Hugues
A1  - Knoblauch, Christian
A1  - Couture, Nicole
A1  - Herzschuh, Ulrike
A1  - Fritz, Michael
T1  - Arctic nearshore sediment dynamics - an example from Herschel Island - Qikiqtaruk, Canada
JF  - Journal of marine science and engineering
N2  - Increasing arctic coastal erosion rates imply a greater release of sediments and organic matter into the coastal zone. With 213 sediment samples taken around Herschel Island-Qikiqtaruk, Canadian Beaufort Sea, we aimed to gain new insights on sediment dynamics and geochemical properties of a shallow arctic nearshore zone. Spatial characteristics of nearshore sediment texture (moderately to poorly sorted silt) are dictated by hydrodynamic processes, but ice-related processes also play a role. We determined organic matter (OM) distribution and inferred the origin and quality of organic carbon by C/N ratios and stable carbon isotopes delta C-13. The carbon content was higher offshore and in sheltered areas (mean: 1.0 wt.%., S.D.: 0.9) and the C/N ratios also showed a similar spatial pattern (mean: 11.1, S.D.: 3.1), while the delta C-13 (mean: -26.4 parts per thousand VPDB, S.D.: 0.4) distribution was more complex. We compared the geochemical parameters of our study with terrestrial and marine samples from other studies using a bootstrap approach. Sediments of the current study contained 6.5 times and 1.8 times less total organic carbon than undisturbed and disturbed terrestrial sediments, respectively. Therefore, degradation of OM and separation of carbon pools take place on land and continue in the nearshore zone, where OM is leached, mineralized, or transported beyond the study area.
KW  - permafrost
KW  - Arctic Ocean
KW  - stable carbon isotopes
KW  - nitrogen
KW  - sediment
KW  - chemistry
KW  - sediment dynamics
KW  - Beaufort Sea
KW  - grain size
Y1  - 2022
U6  - https://doi.org/10.3390/jmse10111589
SN  - 2077-1312
VL  - 10
IS  - 11
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Dallmeyer, Anne
A1  - Kleinen, Thomas
A1  - Claussen, Martin
A1  - Weitzel, Nils
A1  - Cao, Xianyong
A1  - Herzschuh, Ulrike
T1  - The deglacial forest conundrum
JF  - Nature Communications
N2  - How fast the Northern Hemisphere (NH) forest biome tracks strongly warming climates is largely unknown. Regional studies reveal lags between decades and millennia. Here we report a conundrum: Deglacial forest expansion in the NH extra-tropics occurs approximately 4000 years earlier in a transient MPI-ESM1.2 simulation than shown by pollen-based biome reconstructions. Shortcomings in the model and the reconstructions could both contribute to this mismatch, leaving the underlying causes unresolved. The simulated vegetation responds within decades to simulated climate changes, which agree with pollen-independent reconstructions. Thus, we can exclude climate biases as main driver for differences. Instead, the mismatch points at a multi-millennial disequilibrium of the NH forest biome to the climate signal. Therefore, the evaluation of time-slice simulations in strongly changing climates with pollen records should be critically reassessed. Our results imply that NH forests may be responding much slower to ongoing climate changes than Earth System Models predict. <br /> Deglacial forest expansion in the Northern Hemisphere poses a conundrum: Model results agree with the climate signal but are several millennia ahead of reconstructed forest dynamics. The underlying causes remain unsolved.
Y1  - 2022
U6  - https://doi.org/10.1038/s41467-022-33646-6
SN  - 2041-1723
VL  - 13
IS  - 1
PB  - Nature Publishing Group UK
CY  - [London]
ER  - 
TY  - JOUR
A1  - Kruse, Stefan
A1  - Herzschuh, Ulrike
T1  - Regional opportunities for tundra conservation in the next 1000 years
JF  - eLife
N2  - The biodiversity of tundra areas in northern high latitudes is threatened by invasion of forests under global warming. However, poorly understood nonlinear responses of the treeline ecotone mean the timing and extent of tundra losses are unclear, but policymakers need such information to optimize conservation efforts. Our individual-based model LAVESI, developed for the Siberian tundra-taiga ecotone, can help improve our understanding. Consequently, we simulated treeline migration trajectories until the end of the millennium, causing a loss of tundra area when advancing north. Our simulations reveal that the treeline follows climate warming with a severe, century-long time lag, which is overcompensated by infilling of stands in the long run even when temperatures cool again. Our simulations reveal that only under ambitious mitigation strategies (relative concentration pathway 2.6) will ~30% of original tundra areas remain in the north but separated into two disjunct refugia.
KW  - Larix gmelinii
KW  - Larix cajanderi
KW  - nonlinear response
KW  - treeline ecotone
KW  - tundra
KW  - Ecology
KW  - Short Report
Y1  - 2022
U6  - https://doi.org/10.7554/eLife.75163
SN  - 2050-084X
VL  - 11
PB  - eLife Sciences Publications
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Li, Chenzhi
A1  - Postl, Alexander K.
A1  - Böhmer, Thomas
A1  - Cao, Xianyong
A1  - Dolman, Andrew M.
A1  - Herzschuh, Ulrike
T1  - Harmonized chronologies of a global late Quaternary pollen dataset (LegacyAge 1.0)
JF  - Earth system science data : ESSD
N2  - We present a chronology framework named LegacyAge 1.0 containing harmonized chronologies for 2831 pollen records (downloaded from the Neotoma Paleoecology Database and the supplementary Asian datasets) together with their age control points and metadata in machine-readable data formats.  
All chronologies use the Bayesian framework implemented in Bacon version 2.5.3. Optimal parameter settings of priors (accumulation.shape, memory.strength, memory.mean, accumulation.rate, and thickness) were identified based on information in the original publication or iteratively after preliminary model inspection. 
The most common control points for the chronologies are radiocarbon dates (86.1 %), calibrated by the latest calibration curves (IntCal20 and SHCal20 for the terrestrial radiocarbon dates in the Northern Hemisphere and Southern Hemisphere and Marine20 for marine materials). 
The original publications were consulted when dealing with outliers and inconsistencies. Several major challenges when setting up the chronologies included the waterline issue (18.8% of records), reservoir effect (4.9 %), and sediment deposition discontinuity (4.4 %). 
Finally, we numerically compare the LegacyAge 1.0 chronologies to those published in the original publications and show that the reliability of the chronologies of 95.4% of records could be improved according to our assessment. 
Our chronology framework and revised chronologies provide the opportunity to make use of the ages and age uncertainties in synthesis studies of, for example, pollen-based vegetation and climate change. 
The LegacyAge 1.0 dataset, including metadata, datings, harmonized chronologies, and R code used, is openaccess and available at PANGAEA (https://doi.org/10.1594/PANGAEA.933132; Li et al., 2021) and Zenodo (https://doi.org/10.5281/zenodo.5815192; Li et al., 2022), respectively.
Y1  - 2022
U6  - https://doi.org/10.5194/essd-14-1331-2022
SN  - 1866-3508
SN  - 1866-3516
VL  - 14
IS  - 3
SP  - 1331
EP  - 1343
PB  - Copernics Publications
CY  - Katlenburg-Lindau
ER  - 
TY  - JOUR
A1  - Courtin, Jérémy
A1  - Andreev, Andrei
A1  - Raschke, Elena
A1  - Bala, Sarah
A1  - Biskaborn, Boris
A1  - Liu, Sisi
A1  - Zimmermann, Heike
A1  - Diekmann, Bernhard
A1  - Stoof-Leichsenring, Kathleen R.
A1  - Pestryakova, Luidmila Agafyevna
A1  - Herzschuh, Ulrike
T1  - Vegetation changes in Southeastern Siberia during the late pleistocene and the holocene
JF  - Frontiers in Ecology and Evolution
N2  - Relationships between climate, species composition, and species richness are of particular importance for understanding how boreal ecosystems will respond to ongoing climate change. This study aims to reconstruct changes in terrestrial vegetation composition and taxa richness during the glacial Late Pleistocene and the interglacial Holocene in the sparsely studied southeastern Yakutia (Siberia) by using pollen and sedimentary ancient DNA (sedaDNA) records. Pollen and sedaDNA metabarcoding data using the trnL g and h markers were obtained from a sediment core from Lake Bolshoe Toko. Both proxies were used to reconstruct the vegetation composition, while metabarcoding data were also used to investigate changes in plant taxa richness. The combination of pollen and sedaDNA approaches allows a robust estimation of regional and local past terrestrial vegetation composition around Bolshoe Toko during the last similar to 35,000 years. Both proxies suggest that during the Late Pleistocene, southeastern Siberia was covered by open steppe-tundra dominated by graminoids and forbs with patches of shrubs, confirming that steppe-tundra extended far south in Siberia. Both proxies show disturbance at the transition between the Late Pleistocene and the Holocene suggesting a period with scarce vegetation, changes in the hydrochemical conditions in the lake, and in sedimentation rates. Both proxies document drastic changes in vegetation composition in the early Holocene with an increased number of trees and shrubs and the appearance of new tree taxa in the lake's vicinity. The sedaDNA method suggests that the Late Pleistocene steppe-tundra vegetation supported a higher number of terrestrial plant taxa than the forested Holocene. This could be explained, for example, by the "keystone herbivore" hypothesis, which suggests that Late Pleistocene megaherbivores were able to maintain a high plant diversity. This is discussed in the light of the data with the broadly accepted species-area hypothesis as steppe-tundra covered such an extensive area during the Late Pleistocene.
KW  - last glacial
KW  - Holocene
KW  - Lake Bolshoe Toko
KW  - paleoenvironments
KW  - sedimentary ancient DNA
KW  - metabarcoding
KW  - trnL
KW  - pollen
Y1  - 2021
U6  - https://doi.org/10.3389/fevo.2021.625096
SN  - 2296-701X
VL  - 9
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Glückler, Ramesh
A1  - Herzschuh, Ulrike
A1  - Kruse, Stefan
A1  - Andreev, Andrei
A1  - Vyse, Stuart Andrew
A1  - Winkler, Bettina
A1  - Biskaborn, Boris
A1  - Pestryakova, Luidmila Agafyevna
A1  - Dietze, Elisabeth
T1  - Wildfire history of the boreal forest of south-western Yakutia (Siberia) over the last two millennia documented by a lake-sediment charcoal record
JF  - Biogeosciences : BG / European Geosciences Union
N2  - Wildfires, as a key disturbance in forest ecosystems, are shaping the world's boreal landscapes. Changes in fire regimes are closely linked to a wide array of environmental factors, such as vegetation composition, climate change, and human activity. Arctic and boreal regions and, in particular, Siberian boreal forests are experiencing rising air and ground temperatures with the subsequent degradation of permafrost soils leading to shifts in tree cover and species composition. Compared to the boreal zones of North America or Europe, little is known about how such environmental changes might influence long-term fire regimes in Russia. The larch-dominated eastern Siberian deciduous boreal forests differ markedly from the composition of other boreal forests, yet data about past fire regimes remain sparse. Here, we present a high-resolution macroscopic charcoal record from lacustrine sediments of Lake Khamra (southwest Yakutia, Siberia) spanning the last ca. 2200 years, including information about charcoal particle sizes and morphotypes. Our results reveal a phase of increased charcoal accumulation between 600 and 900 CE, indicative of relatively high amounts of burnt biomass and high fire frequencies. This is followed by an almost 900-year-long period of low charcoal accumulation without significant peaks likely corresponding to cooler climate conditions. After 1750 CE fire frequencies and the relative amount of biomass burnt start to increase again, coinciding with a warming climate and increased anthropogenic land development after Russian colonization. In the 20th century, total charcoal accumulation decreases again to very low levels despite higher fire frequency, potentially reflecting a change in fire management strategies and/or a shift of the fire regime towards more frequent but smaller fires. A similar pattern for different charcoal morphotypes and comparison to a pollen and non-pollen palynomorph (NPP) record from the same sediment core indicate that broad-scale changes in vegetation composition were probably not a major driver of recorded fire regime changes. Instead, the fire regime of the last two millennia at Lake Khamra seems to be controlled mainly by a combination of short-term climate variability and anthropogenic fire ignition and suppression.
Y1  - 2021
U6  - https://doi.org/10.5194/bg-18-4185-2021
SN  - 1726-4170
SN  - 1726-4189
VL  - 18
IS  - 13
SP  - 4185
EP  - 4209
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Liu, Sisi
A1  - Stoof-Leichsenring, Kathleen Rosemarie
A1  - Kruse, Stefan
A1  - Pestryakova, Luidmila Agafyevna
A1  - Herzschuh, Ulrike
T1  - Holocene vegetation and plant diversity changes in the north-eastern Siberian treeline region from pollen and sedimentary ancient DNA
JF  - Frontiers in Ecology and Evolution
N2  - Although sedimentary ancient DNA (sedaDNA) has been increasingly used to study paleoecological dynamics (Schulte et al., 2020), the approach has rarely been compared with the traditional method of pollen analysis for investigating past changes in the vegetation composition and diversity of Arctic treeline areas. Here, we provide a history of latitudinal floristic composition and species diversity based on a comparison ofsedaDNA and pollen data archived in three Siberian lake sediment cores spanning the mid-Holocene to the present (7.6-0 cal ka BP), from northern typical tundra to southern open larch forest in the Omoloy region. Our results show that thesedaDNA approach identifies more plant taxa found in the local vegetation communities, while the corresponding pollen analysis mainly captures the regional vegetation development and has its limitations for plant diversity reconstruction. Measures of alpha diversity were calculated based onsedaDNA data recovered from along a tundra to forest tundra to open larch forest gradient. Across all sites,sedaDNA archives provide a complementary record of the vegetation transition within each lake's catchment, tracking a distinct latitudinal vegetation type range from larch tree/alder shrub (open larch forest site) to dwarf shrub-steppe (forest tundra) to wet sedge tundra (typical tundra site). By contrast, the pollen data reveal an open landscape, which cannot distinguish the temporal changes in compositional vegetation for the open larch forest site and forest-tundra site. IncreasingLarixpollen percentages were recorded in the forest-tundra site in the last millenium although noLarixDNA was detected, suggesting that thesedaDNA approach performs better for tracking the local establishment ofLarix. Highest species richness and diversity are found in the mid-Holocene (before 4.4 ka) at the typical tundra site with a diverse range of vegetational habitats, while lowest species richness is recorded for the forest tundra where dwarf-willow habitats dominated the lake's catchment. During the late Holocene, strong declines in species richness and diversity are found at the typical tundra site with the vegetation changing to relatively simple communities. Nevertheless, plant species richness is mostly higher than at the forest-tundra site, which shows a slightly decreasing trend. Plant species richness at the open larch forest site fluctuates through time and is higher than the other sites since around 2.5 ka. Taken together, there is no evidence to suggest that the latitudinal gradients in species diversity changes are present at a millennial scale. Additionally, a weak correlation between the principal component analysis (PCA) site scores ofsedaDNA and species richness suggests that climate may not be a direct driver of species turnover within a lake's catchment. Our data suggest thatsedaDNA and pollen have different but complementary abilities for reconstructing past vegetation and species diversity along a latitude.
KW  - sedimentary ancient DNA
KW  - metabarcoding
KW  - pollen
KW  - Siberia
KW  - palaeovegetation
KW  - plant diversity
KW  - latitudinal gradient
Y1  - 2020
U6  - https://doi.org/10.3389/fevo.2020.560243
SN  - 2296-701X
VL  - 8
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Cao, Xianyong
A1  - Tian, Fang
A1  - Andreev, Andrei
A1  - Anderson, Patricia M.
A1  - Lozhkin, Anatoly V.
A1  - Bezrukova, Elena
A1  - Ni, Jian
A1  - Rudaya, Natalia
A1  - Stobbe, Astrid
A1  - Wieczorek, Mareike
A1  - Herzschuh, Ulrike
T1  - A taxonomically harmonized and temporally standardized fossil pollen dataset from Siberia covering the last 40 kyr
JF  - Earth System Science Data
N2  - Pollen records from Siberia are mostly absent in global or Northern Hemisphere synthesis works. Here we present a taxonomically harmonized and temporally standardized pollen dataset that was synthesized using 173 palynological records from Siberia and adjacent areas (northeastern Asia, 42-75 degrees N, 50-180 degrees E). Pollen data were taxonomically harmonized, i.e. the original 437 taxa were assigned to 106 combined pollen taxa. Age-depth models for all records were revised by applying a constant Bayesian age-depth modelling routine. The pollen dataset is available as count data and percentage data in a table format (taxa vs. samples), with age information for each sample. The dataset has relatively few sites covering the last glacial period between 40 and 11.5 ka (calibrated thousands of years before 1950 CE) particularly from the central and western part of the study area. In the Holocene period, the dataset has many sites from most of the area, with the exception of the central part of Siberia. Of the 173 pollen records, 81 % of pollen counts were downloaded from open databases (GPD, EPD, PANGAEA) and 10 % were contributions by the original data gatherers, while a few were digitized from publications. Most of the pollen records originate from peatlands (48 %) and lake sediments (33 %). Most of the records (83 %) have >= 3 dates, allowing the establishment of reliable chronologies. The dataset can be used for various purposes, including pollen data mapping (example maps for Larix at selected time slices are shown) as well as quantitative climate and vegetation reconstructions. The datasets for pollen counts and pollen percentages are available at https://doi.org/10.1594/PANGAEA.898616 (Cao et al., 2019a), also including the site information, data source, original publication, dating data, and the plant functional type for each pollen taxa.
KW  - Late Quaternary vegetation
KW  - Holocene environmental history
KW  - eastern continental Asia
KW  - plant macrofossil data
KW  - late pleistocene
KW  - paleoenvironmental records
KW  - Verkhoyansk mountains
KW  - climate dynamics
KW  - glacial maximum
KW  - Northern Asia
Y1  - 2020
U6  - https://doi.org/10.5194/essd-12-119-2020
SN  - 1866-3508
SN  - 1866-3516
VL  - 12
IS  - 1
SP  - 119
EP  - 135
PB  - Copernics Publications
CY  - Katlenburg-Lindau
ER  - 
TY  - JOUR
A1  - Schmidt, Lena Katharina
A1  - Francke, Till
A1  - Rottler, Erwin
A1  - Blume, Theresa
A1  - Schöber, Johannes
A1  - Bronstert, Axel
T1  - Suspended sediment and discharge dynamics in a glaciated alpine environment
BT  - identifying crucial areas and time periods on several spatial and temporal scales in the Ötztal, Austria
JF  - Earth surface dynamics
N2  - Glaciated high-alpine areas are fundamentally altered by climate change, with well-known implications for hydrology, e.g., due to glacier retreat, longer snow-free periods, and more frequent and intense summer rainstorms. While knowledge on how these hydrological changes will propagate to suspended sediment dynamics is still scarce, it is needed to inform mitigation and adaptation strategies. To understand the processes and source areas most relevant to sediment dynamics, we analyzed discharge and sediment dynamics in high temporal resolution as well as their patterns on several spatial scales, which to date few studies have done.

We used a nested catchment setup in the Upper Ötztal in Tyrol, Austria, where high-resolution (15 min) time series of discharge and suspended sediment concentrations are available for up to 15 years (2006–2020). The catchments of the gauges in Vent, Sölden and Tumpen range from 100 to almost 800 km2 with 10 % to 30 % glacier cover and span an elevation range of 930 to 3772 m a.s.l. We analyzed discharge and suspended sediment yields (SSY), their distribution in space, their seasonality and spatial differences therein, and the relative importance of short-term events. We complemented our analysis by linking the observations to satellite-based snow cover maps, glacier inventories, mass balances and precipitation data.

Our results indicate that the areas above 2500 m a.s.l., characterized by glacier tongues and the most recently deglaciated areas, are crucial for sediment generation in all sub-catchments. This notion is supported by the synchronous spring onset of sediment export at the three gauges, which coincides with snowmelt above 2500 m but lags behind spring discharge onsets. This points at a limitation of suspended sediment supply as long as the areas above 2500 m are snow-covered. The positive correlation of annual SSY with glacier cover (among catchments) and glacier mass balances (within a catchment) further supports the importance of the glacier-dominated areas. The analysis of short-term events showed that summer precipitation events were associated with peak sediment concentrations and yields but on average accounted for only 21 % of the annual SSY in the headwaters. These results indicate that under current conditions, thermally induced sediment export (through snow and glacier melt) is dominant in the study area.

Our results extend the scientific knowledge on current hydro-sedimentological conditions in glaciated high-alpine areas and provide a baseline for studies on projected future changes in hydro-sedimentological system dynamics.
Y1  - 2022
U6  - https://doi.org/10.5194/esurf-10-653-2022
SN  - 2196-632X
SN  - 2196-6311
VL  - 10
IS  - 3
SP  - 653
EP  - 669
PB  - Copernicus Publications
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Walch, Daniela M. R.
A1  - Singh, Rakesh K.
A1  - Soreide, Janne E.
A1  - Lantuit, Hugues
A1  - Poste, Amanda
T1  - Spatio-temporal variability of suspended particulate matter in a high-arctic estuary (Adventfjorden, Svalbard) using sentinel-2 time-series
JF  - Remote sensing
N2  - Arctic coasts, which feature land-ocean transport of freshwater, sediments, and other terrestrial material, are impacted by climate change, including increased temperatures, melting glaciers, changes in precipitation and runoff. 
These trends are assumed to affect productivity in fjordic estuaries. 
However, the spatial extent and temporal variation of the freshwater-driven darkening of fjords remain unresolved. 

The present study illustrates the spatio-temporal variability of suspended particulate matter (SPM) in the Adventfjorden estuary, Svalbard, using in-situ field campaigns and ocean colour remote sensing (OCRS) via high-resolution Sentinel-2 imagery. 
To compute SPM concentration (C-SPMsat), a semi-analytical algorithm was regionally calibrated using local in-situ data, which improved the accuracy of satellite-derived SPM concentration by similar to 20% (MRD). Analysis of SPM concentration for two consecutive years (2019, 2020) revealed strong seasonality of SPM in Adventfjorden. 
Highest estimated SPM concentrations and river plume extent (% of fjord with C-SPMsat > 30 mg L-1) occurred during June, July, and August. 

Concurrently, we observed a strong relationship between river plume extent and average air temperature over the 24 h prior to the observation (R-2 = 0.69). 
Considering predicted changes to environmental conditions in the Arctic region, this study highlights the importance of the rapidly changing environmental parameters and the significance of remote sensing in analysing fluxes in light attenuating particles, especially in the coastal Arctic Ocean.
KW  - ocean colour
KW  - coastal darkening
KW  - SPM
KW  - sediment plumes
KW  - Arctic coast
KW  - remote sensing
KW  - regional tuning
KW  - coastal ecosystems;
KW  - land-ocean-interaction
KW  - riverine inputs
Y1  - 2022
U6  - https://doi.org/10.3390/rs14133123
SN  - 2072-4292
VL  - 14
IS  - 13
PB  - MDPI
CY  - Basel
ER  -