38842
2015
2015
eng
2796
2820
25
6
7
article
MDPI
Basel
1
--
--
--
Climate or Land Use?
This study intends to contribute to the ongoing discussion on whether land use and land cover changes (LULC) or climate trends have the major influence on the observed increase of flood magnitudes in the Sahel. A simulation-based approach is used for attributing the observed trends to the postulated drivers. For this purpose, the ecohydrological model SWIM (Soil and Water Integrated Model) with a new, dynamic LULC module was set up for the Sahelian part of the Niger River until Niamey, including the main tributaries Sirba and Goroul. The model was driven with observed, reanalyzed climate and LULC data for the years 1950-2009. In order to quantify the shares of influence, one simulation was carried out with constant land cover as of 1950, and one including LULC. As quantitative measure, the gradients of the simulated trends were compared to the observed trend. The modeling studies showed that for the Sirba River only the simulation which included LULC was able to reproduce the observed trend. The simulation without LULC showed a positive trend for flood magnitudes, but underestimated the trend significantly. For the Goroul River and the local flood of the Niger River at Niamey, the simulations were only partly able to reproduce the observed trend. In conclusion, the new LULC module enabled some first quantitative insights into the relative influence of LULC and climatic changes. For the Sirba catchment, the results imply that LULC and climatic changes contribute in roughly equal shares to the observed increase in flooding. For the other parts of the subcatchment, the results are less clear but show, that climatic changes and LULC are drivers for the flood increase; however their shares cannot be quantified. Based on these modeling results, we argue for a two-pillar adaptation strategy to reduce current and future flood risk: Flood mitigation for reducing LULC-induced flood increase, and flood adaptation for a general reduction of flood vulnerability.
Water
Attribution of Changes in River Flooding in the Sahel Zone
10.3390/w7062796
2073-4441
wos:2015
WOS:000361034400002
Aich, V (reprint author), Potsdam Inst Climate Impact Res PIK, D-14473 Potsdam, Germany., aich@pik-potsdam.de; liersch@pik-potsdam.de; vetter@pik-potsdam.de; jafet.andersson@smhi.se; eva.mueller@uni-potsdam.de; hattermann@pik-potsdam.de
IMPACT2C project
Valentin Aich
Stefan Liersch
Tobias Vetter
Jafet C. M. Andersson
Eva Nora Müller
Fred Fokko Hattermann
Institut für Geowissenschaften
Referiert
Open Access
Institut für Erd- und Umweltwissenschaften
40011
2017
2017
eng
25
postprint
1
--
2017-09-01
--
Climate or land use?
This study intends to contribute to the ongoing discussion on whether land use and land cover changes (LULC) or climate trends have the major influence on the observed increase of flood magnitudes in the Sahel. A simulation-based approach is used for attributing the observed trends to the postulated drivers. For this purpose, the ecohydrological model SWIM (Soil and Water Integrated Model) with a new, dynamic LULC module was set up for the Sahelian part of the Niger River until Niamey, including the main tributaries Sirba and Goroul. The model was driven with observed, reanalyzed climate and LULC data for the years 1950–2009. In order to quantify the shares of influence, one simulation was carried out with constant land cover as of 1950, and one including LULC. As quantitative measure, the gradients of the simulated trends were compared to the observed trend. The modeling studies showed that for the Sirba River only the simulation which included LULC was able to reproduce the observed trend. The simulation without LULC showed a positive trend for flood magnitudes, but underestimated the trend significantly. For the Goroul River and the local flood of the Niger River at Niamey, the simulations were only partly able to reproduce the observed trend. In conclusion, the new LULC module enabled some first quantitative insights into the relative influence of LULC and climatic changes. For the Sirba catchment, the results imply that LULC and climatic changes contribute in roughly equal shares to the observed increase in flooding. For the other parts of the subcatchment, the results are less clear but show, that climatic changes and LULC are drivers for the flood increase; however their shares cannot be quantified. Based on these modeling results, we argue for a two-pillar adaptation strategy to reduce current and future flood risk: Flood mitigation for reducing LULC-induced flood increase, and flood adaptation for a general reduction of flood vulnerability.
Attribution of changes in river flooding in the Sahel Zone
urn:nbn:de:kobv:517-opus4-400115
online registration
Water 7 (2015) Nr. 6, S. 2796-2820. - DOI: 10.3390/w7062796
CC-BY - Namensnennung 4.0 International
Valentin Aich
Stefan Liersch
Tobias Vetter
Jafet C. M. Andersson
Eva Nora Müller
Fred Fokko Hattermann
Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
345
eng
uncontrolled
simulation-based attribution
eng
uncontrolled
Sahel
eng
uncontrolled
Niger River
eng
uncontrolled
climate variability
eng
uncontrolled
hydrological modeling
eng
uncontrolled
flood mitigation
eng
uncontrolled
flood adaptation
Geowissenschaften
open_access
Institut für Geowissenschaften
Referiert
Open Access
Multidisciplinary Digital Publishing Institute (MDPI)
Institut für Erd- und Umweltwissenschaften
Universität Potsdam
https://publishup.uni-potsdam.de/files/40011/pmnr345_online.pdf
38291
2014
2014
eng
1305
1321
17
4
18
article
Copernicus
Göttingen
1
--
--
--
Comparing impacts of climate change on streamflow in four large African river basins
This study aims to compare impacts of climate change on streamflow in four large representative African river basins: the Niger, the Upper Blue Nile, the Oubangui and the Limpopo. We set up the eco-hydrological model SWIM (Soil and Water Integrated Model) for all four basins individually. The validation of the models for four basins shows results from adequate to very good, depending on the quality and availability of input and calibration data.
For the climate impact assessment, we drive the model with outputs of five bias corrected Earth system models of Coupled Model Intercomparison Project Phase 5 (CMIP5) for the representative concentration pathways (RCPs) 2.6 and 8.5. This climate input is put into the context of climate trends of the whole African continent and compared to a CMIP5 ensemble of 19 models in order to test their representativeness. Subsequently, we compare the trends in mean discharges, seasonality and hydrological extremes in the 21st century. The uncertainty of results for all basins is high. Still, climate change impact is clearly visible for mean discharges but also for extremes in high and low flows. The uncertainty of the projections is the lowest in the Upper Blue Nile, where an increase in streamflow is most likely. In the Niger and the Limpopo basins, the magnitude of trends in both directions is high and has a wide range of uncertainty. In the Oubangui, impacts are the least significant. Our results confirm partly the findings of previous continental impact analyses for Africa. However, contradictory to these studies we find a tendency for increased streamflows in three of the four basins (not for the Oubangui). Guided by these results, we argue for attention to the possible risks of increasing high flows in the face of the dominant water scarcity in Africa. In conclusion, the study shows that impact intercomparisons have added value to the adaptation discussion and may be used for setting up adaptation plans in the context of a holistic approach.
Hydrology and earth system sciences : HESS
10.5194/hess-18-1305-2014
1027-5606
1607-7938
wos:2014
WOS:000335375300005
Aich, V (reprint author), Potsdam Inst Climate Impact Res, Potsdam, Germany., aich@pik-potsdam.de
IMPACT2c project
Valentin Aich
Stefan Liersch
T. Vetter
S. Huang
J. Tecklenburg
P. Hoffmann
H. Koch
S. Fournet
Valentina Krysanova
N. Mueller
Fred Fokko Hattermann
Institut für Geowissenschaften
Referiert
Open Access
Institut für Erd- und Umweltwissenschaften
9157
2015
2016
eng
xxi, 275
doctoralthesis
1
--
--
2016-04-15
Floods in the Niger River Basin in the face of global change
Hochwasser im Niger Einzugsgebiet im Kontext des Globalen Wandels
In the last decade, the number and dimensions of catastrophic flooding events in the Niger River Basin (NRB) have markedly increased. Despite the devastating impact of the floods on the population and the mainly agriculturally based economy of the riverine nations, awareness of the hazards in policy and science is still low. The urgency of this topic and the existing research deficits are the motivation for the present dissertation.
The thesis is an initial detailed assessment of the increasing flood risk in the NRB. The research strategy is based on four questions regarding (1) features of the change in flood risk, (2) reasons for the change in the flood regime, (3) expected changes of the flood regime given climate and land use changes, and (4) recommendations from previous analysis for reducing the flood risk in the NRB.
The question examining the features of change in the flood regime is answered by means of statistical analysis. Trend, correlation, changepoint, and variance analyses show that, in addition to the factors exposure and vulnerability, the hazard itself has also increased significantly in the NRB, in accordance with the decadal climate pattern of West Africa. The northern arid and semi-arid parts of the NRB are those most affected by the changes.
As potential reasons for the increase in flood magnitudes, climate and land use changes are attributed by means of a hypothesis-testing framework. Two different approaches, based on either data analysis or simulation, lead to similar results, showing that the influence of climatic changes is generally larger compared to that of land use changes. Only in the dry areas of the NRB is the influence of land use changes comparable to that of climatic alterations.
Future changes of the flood regime are evaluated using modelling results. First ensembles of statistically and dynamically downscaled climate models based on different emission scenarios are analyzed. The models agree with a distinct increase in temperature. The precipitation signal, however, is not coherent. The climate scenarios are used to drive an eco-hydrological model. The influence of climatic changes on the flood regime is uncertain due to the unclear precipitation signal. Still, in general, higher flood peaks are expected. In a next step, effects of land use changes are integrated into the model. Different scenarios show that regreening might help to reduce flood peaks. In contrast, an expansion of agriculture might enhance the flood peaks in the NRB. Similarly to the analysis of observed changes in the flood regime, the impacts of climate- and land use changes for the future scenarios are also most severe in the dry areas of the NRB.
In order to answer the final research question, the results of the above analysis are integrated into a range of recommendations for science and policy on how to reduce flood risk in the NRB. The main recommendations include a stronger consideration of the enormous natural climate variability in the NRB and a focus on so called “no-regret” adaptation strategies which account for high uncertainty, as well as a stronger consideration of regional differences. Regarding the prevention and mitigation of catastrophic flooding, the most vulnerable and sensitive areas in the basin, the arid and semi-arid Sahelian and Sudano-Sahelian regions, should be prioritized. Eventually, an active, science-based and science-guided flood policy is recommended. The enormous population growth in the NRB in connection with the expected deterioration of environmental and climatic conditions is likely to enhance the region´s vulnerability to flooding. A smart and sustainable flood policy can help mitigate these negative impacts of flooding on the development of riverine societies in West Africa.
Während des vergangenen Jahrzehnts nahmen die Anzahl und die Ausmaße von katastrophalen Hochwassern im Einzugsgebiet des Nigerflussess (NEZG) deutlich zu. Trotz der verheerenden Auswirkungen der Hochwasserkatastrophen auf die Menschen und die hauptsächlich auf Landwirtschaft basierende Wirtschaft der Anrainerstaaten wird das Thema von Politik und Wissenschaft noch kaum beachtet.
Die vorliegende Dissertation ist die erste ausführliche Analyse des steigenden Hochwasserrisikos im NEZG. Die Forschungsstrategie basiert auf vier Fragen nach (1) der Art der Veränderungen des Hochwasserrisikos, (2) den Ursachen der Veränderungen im Hochwasserregime, (3) den zukünftigen Entwicklungen im Hochwasserregime hinsichtlich der erwartenden Klima- und Landnutzungswandel und (4) den aus den Untersuchungen abgeleiteten Empfehlungen zur Reduzierung des Hochwasserrisikos im NEZG.
Die Frage nach den Merkmalen der Veränderungen im Hochwasserrisiko wurde mithilfe von statistischen Untersuchungen beantwortet. Die Analysen zeigen, dass neben den Risikofaktoren Exponiertheit und Verwundbarkeit auch die Hochwasserstände selbst im NEZG in den letzten Jahrzehnten signifikant und entsprechend der typischen dekadischen Klimamuster Westafrikas angestiegen sind.
Als potentielle Ursachen des Hochwasseranstiegs werden Klima- und Landnutzungswandel untersucht. Zwei verschiedene Ansätze, basierend auf Daten sowie auf Simulationen, führen zu ähnlichen Ergebnissen und zeigen, dass der Einfluss der Klimaveränderungen im Allgemeinen größer als der des Landnutzungswandels ist.
Das zukünftige Hochwasserrisiko wird anhand des öko-hydrologisches Modells SWIM abgeschätzt. Der Einfluss des Klimawandels auf das Hochwasserregime ist auf Grund des problematischen Niederschlagssignals unsicher. Tendenziell werden aber höhere Maximalabflüsse erwartet. Der Effekt der Landnutzungsänderung beeinflusst das Hochwasserverhalten ebenfalls stark, besonders in den trockenen Gebieten. Verschiedene Szenarien zeigen, dass Renaturierung hülfe, Hochwasserspitzen zu kappen. Eine Ausweitung der Agrarflächen dagegen würde die Hochwässer im NEZG weiter verstärken
Zentrale Empfehlungen sind eine stärkere Einbeziehung der enorm starken natürlichen Klimavariabilität im NEZG und eine Fokussierung auf sogenannte „no-regret“ Anpassungsstrategien. Dabei sollte den verwundbarsten Regionen des Einzugsgebiets, den ariden und semi-ariden Regionen, Priorität eingeräumt werden. Die enorme Bevölkerungszunahme im NEZG verbunden mit der zu erwartenden Verschlechterung der Umwelt- und Klimabedingungen wird mit hoher Wahrscheinlichkeit auch die Verwundbarkeit bezüglich Hochwässer weiter ansteigen lassen. Eine vernünftige und nachhaltige Hochwasserpolitik kann helfen, die negativen Folgen auf die Entwicklung der Anrainerstaaten des Nigerflusses abzumindern.
analysis, attribution and projections
Analyse, Zuschreibung und Projektionen
urn:nbn:de:kobv:517-opus4-91577
online registration
Potsdam, Univ., Diss., 2016
RS 10363, RS 10438, AR 14120
Keine öffentliche Lizenz: Unter Urheberrechtsschutz
Valentin Aich
eng
uncontrolled
flood
eng
uncontrolled
Niger
eng
uncontrolled
climate change
eng
uncontrolled
land use change
deu
uncontrolled
Hochwasser
deu
uncontrolled
Niger
deu
uncontrolled
Klimawandel
deu
uncontrolled
Landnutzungswandel
Geowissenschaften
open_access
Institut für Geowissenschaften
Institut für Erd- und Umweltwissenschaften
Universität Potsdam
Universität Potsdam
https://publishup.uni-potsdam.de/files/9157/aich_diss.pdf
49629
2021
2021
eng
16
1127
postprint
1
2021-02-24
2021-02-24
--
Increasing compound warm spells and droughts in the Mediterranean Basin
The co-occurrence of warm spells and droughts can lead to detrimental socio-economic and ecological impacts, largely surpassing the impacts of either warm spells or droughts alone. We quantify changes in the number of compound warm spells and droughts from 1979 to 2018 in the Mediterranean Basin using the ERA5 data set. We analyse two types of compound events: 1) warm season compound events, which are extreme in absolute terms in the warm season from May to October and 2) year-round deseasonalised compound events, which are extreme in relative terms respective to the time of the year. The number of compound events increases significantly and especially warm spells are increasing strongly – with an annual growth rates of 3.9 (3.5) % for warm season (deseasonalised) compound events and 4.6 (4.4) % for warm spells –, whereas for droughts the change is more ambiguous depending on the applied definition. Therefore, the rise in the number of compound events is primarily driven by temperature changes and not the lack of precipitation. The months July and August show the highest increases in warm season compound events, whereas the highest increases of deseasonalised compound events occur in spring and early summer. This increase in deseasonalised compound events can potentially have a significant impact on the functioning of Mediterranean ecosystems as this is the peak phase of ecosystem productivity and a vital phenophase.
Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
10.25932/publishup-49629
urn:nbn:de:kobv:517-opus4-496294
1866-8372
Weather and Climate Extremes 23 (2021) Art. 100312 DOI: 10.1016/j.wace.2021.100312
100312
<a href="http://publishup.uni-potsdam.de/49628">Bibliographieeintrag der Originalveröffentlichung/Quelle</a>
false
true
CC-BY - Namensnennung 4.0 International
Johannes Vogel
Eva Paton
Valentin Aich
Axel Bronstert
Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
1127
eng
uncontrolled
Compound events
eng
uncontrolled
Warm spells
eng
uncontrolled
Droughts
eng
uncontrolled
Mediterranean basin
eng
uncontrolled
Extreme events
eng
uncontrolled
Climate change
Geowissenschaften
open_access
Referiert
Institut für Umweltwissenschaften und Geographie
Green Open-Access
Universität Potsdam
https://publishup.uni-potsdam.de/files/49629/pmnr1127.pdf
49628
2021
2021
eng
14
32
article
Elsevier
Amsterdam
1
2021-02-17
2021-02-17
--
Increasing compound warm spells and droughts in the Mediterranean Basin
The co-occurrence of warm spells and droughts can lead to detrimental socio-economic and ecological impacts, largely surpassing the impacts of either warm spells or droughts alone. We quantify changes in the number of compound warm spells and droughts from 1979 to 2018 in the Mediterranean Basin using the ERA5 data set. We analyse two types of compound events: 1) warm season compound events, which are extreme in absolute terms in the warm season from May to October and 2) year-round deseasonalised compound events, which are extreme in relative terms respective to the time of the year. The number of compound events increases significantly and especially warm spells are increasing strongly – with an annual growth rates of 3.9 (3.5) % for warm season (deseasonalised) compound events and 4.6 (4.4) % for warm spells –, whereas for droughts the change is more ambiguous depending on the applied definition. Therefore, the rise in the number of compound events is primarily driven by temperature changes and not the lack of precipitation. The months July and August show the highest increases in warm season compound events, whereas the highest increases of deseasonalised compound events occur in spring and early summer. This increase in deseasonalised compound events can potentially have a significant impact on the functioning of Mediterranean ecosystems as this is the peak phase of ecosystem productivity and a vital phenophase.
Weather and climate extremes
10.1016/j.wace.2021.100312
2212-0947
Universität Potsdam
PA 2021_017
2034.90
100312
<a href="https://doi.org/10.25932/publishup-49629">Zweitveröffentlichung in der Schriftenreihe Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe ; 1127</a>
WOS:000663360800002
Vogel, Johannes (corresponding author), Univ Potsdam, Inst Environm Sci & Geog, Potsdam, Germany.
Vogel, Johannes
DFG research training group "Natural Hazards and Risks in a Changing World" (NatRiskChange)German Research Foundation (DFG)
GRK 2043
CC-BY - Namensnennung 4.0 International
Johannes Vogel
Eva Paton
Valentin Aich
Axel Bronstert
eng
uncontrolled
Compound events
eng
uncontrolled
Warm spells
eng
uncontrolled
Droughts
eng
uncontrolled
Mediterranean basin
eng
uncontrolled
Extreme events
eng
uncontrolled
Climate change
Geowissenschaften
open_access
Referiert
Publikationsfonds der Universität Potsdam
Institut für Umweltwissenschaften und Geographie
Gold Open-Access
DOAJ gelistet
37463
2014
2014
eng
120
129
10
122
article
Elsevier
Amsterdam
1
--
--
--
Quantification and interpretation of suspended-sediment discharge hysteresis patterns: How much data do we need?
Sediment-discharge hysteresis loops are frequently analyzed to facilitate the understanding of sediment transport processes. Hysteresis patterns, however, are often complex and their interpretation can be complicated. Particularly, quantifying hysteresis patterns remains a problematic issue. Moreover, it is currently unknown how much data is required for analyzing sediment-discharge hysteresis loops in a given area. These open questions and challenges motivated us to develop a new method for quantifying suspended-sediment hysteresis. Subsequently, we applied the new hysteresis index to three suspended-sediment and discharge datasets from a small tropical rainforest catchment. The datasets comprised a different number of events and sampling sites. Our analyses show three main findings: (1) datasets restricted to only few events, which is typical for rapid assessment surveys, were always sufficient to identify the dominating hysteresis pattern in our research area. Furthermore, some of these small datasets contained multiple-peak events that allowed identifying intra-event exhaustion effects and hence, limitations in sediment supply. (2) Datasets comprising complete hydrological years were particularly useful for analyzing seasonal dynamics of hysteresis. These analyses revealed an exhaustion of hysteresis on the inter-event scale which also points to a limited sediment supply. (3) Datasets comprising measurements from two consecutive gauges installed at the catchment outlet and on a slope within that catchment allowed analyzing the change of hysteresis patterns along the flowpath. On the slope, multiple-peak events showed a stronger intra-event exhaustion of hysteresis than at the catchment outlet. Furthermore, exhaustion of hysteresis on the inter-event scale was not evident on the slope but occurred at the catchment outlet. Our results indicate that even small sediment datasets can provide valuable insights into sediment transport processes of small catchments. Furthermore, our results may serve as a first guideline on what to expect from an analysis of hysteresis patterns for datasets of varying quality and quantity. (c) 2014 Elsevier B.V. All rights reserved.
Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution
10.1016/j.catena.2014.06.020
0341-8162
1872-6887
wos:2014
WOS:000341349700011
Aich, V (reprint author), Potsdam Inst Climate Impact Res PIK, POB 60 12 03, D-14412 Potsdam, Germany., aich@pik-potsdam.de
German Research Foundation [El 255/6-1]; STRI
Valentin Aich
Alexander Zimmermann
Helmut Elsenbeer
eng
uncontrolled
Suspended sediment
eng
uncontrolled
Hysteresis index
eng
uncontrolled
Sediment monitoring
eng
uncontrolled
Overland flow
eng
uncontrolled
Tropical forest
Institut für Geowissenschaften
Referiert
Institut für Erd- und Umweltwissenschaften
55498
2021
2021
eng
5903
5927
25
22
18
article
Copernicus
Göttingen
1
2021-11-17
2021-11-17
--
Seasonal ecosystem vulnerability to climatic anomalies in the Mediterranean
Mediterranean ecosystems are particularly vulnerable to climate change and the associated increase in climate anomalies. This study investigates extreme ecosystem responses evoked by climatic drivers in the Mediterranean Basin for the time span 1999–2019 with a specific focus on seasonal variations as the seasonal timing of climatic anomalies is considered essential for impact and vulnerability assessment. A bivariate vulnerability analysis is performed for each month of the year to quantify which combinations of the drivers temperature (obtained from ERA5-Land) and soil moisture (obtained from ESA CCI and ERA5-Land) lead to extreme reductions in ecosystem productivity using the fraction of absorbed photosynthetically active radiation (FAPAR; obtained from the Copernicus Global Land Service) as a proxy.
The bivariate analysis clearly showed that, in many cases, it is not just one but a combination of both drivers that causes ecosystem vulnerability. The overall pattern shows that Mediterranean ecosystems are prone to three soil moisture regimes during the yearly cycle: they are vulnerable to hot and dry conditions from May to July, to cold and dry conditions from August to October, and to cold conditions from November to April, illustrating the shift from a soil-moisture-limited regime in summer to an energy-limited regime in winter. In late spring, a month with significant vulnerability to hot conditions only often precedes the next stage of vulnerability to both hot and dry conditions, suggesting that high temperatures lead to critically low soil moisture levels with a certain time lag. In the eastern Mediterranean, the period of vulnerability to hot and dry conditions within the year is much longer than in the western Mediterranean. Our results show that it is crucial to account for both spatial and temporal variability to adequately assess ecosystem vulnerability. The seasonal vulnerability approach presented in this study helps to provide detailed insights regarding the specific phenological stage of the year in which ecosystem vulnerability to a certain climatic condition occurs.
How to cite.
Vogel, J., Paton, E., and Aich, V.: Seasonal ecosystem vulnerability to climatic anomalies in the Mediterranean, Biogeosciences, 18, 5903–5927, https://doi.org/10.5194/bg-18-5903-2021, 2021.
Biogeosciences
10.5194/bg-18-5903-2021
1726-4189
Vogel, Johannes
<a href="https://doi.org/10.25932/publishup-55497">Zweitveröffentlichung in der Schriftenreihe Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe ; 1252</a>
false
false
CC-BY - Namensnennung 4.0 International
Johannes Vogel
Eva Nora Paton
Valentin Aich
Geowissenschaften
Extern
Referiert
Publikationsfonds der Universität Potsdam
Institut für Umweltwissenschaften und Geographie
Gold Open-Access
55497
2021
2022
eng
5903
5927
25
22
18
postprint
Universitätsverlag Potsdam
Potsdam
1
2022-07-07
2022-07-07
--
Seasonal ecosystem vulnerability to climatic anomalies in the Mediterranean
Mediterranean ecosystems are particularly vulnerable to climate change and the associated increase in climate anomalies. This study investigates extreme ecosystem responses evoked by climatic drivers in the Mediterranean Basin for the time span 1999–2019 with a specific focus on seasonal variations as the seasonal timing of climatic anomalies is considered essential for impact and vulnerability assessment. A bivariate vulnerability analysis is performed for each month of the year to quantify which combinations of the drivers temperature (obtained from ERA5-Land) and soil moisture (obtained from ESA CCI and ERA5-Land) lead to extreme reductions in ecosystem productivity using the fraction of absorbed photosynthetically active radiation (FAPAR; obtained from the Copernicus Global Land Service) as a proxy.
The bivariate analysis clearly showed that, in many cases, it is not just one but a combination of both drivers that causes ecosystem vulnerability. The overall pattern shows that Mediterranean ecosystems are prone to three soil moisture regimes during the yearly cycle: they are vulnerable to hot and dry conditions from May to July, to cold and dry conditions from August to October, and to cold conditions from November to April, illustrating the shift from a soil-moisture-limited regime in summer to an energy-limited regime in winter. In late spring, a month with significant vulnerability to hot conditions only often precedes the next stage of vulnerability to both hot and dry conditions, suggesting that high temperatures lead to critically low soil moisture levels with a certain time lag. In the eastern Mediterranean, the period of vulnerability to hot and dry conditions within the year is much longer than in the western Mediterranean. Our results show that it is crucial to account for both spatial and temporal variability to adequately assess ecosystem vulnerability. The seasonal vulnerability approach presented in this study helps to provide detailed insights regarding the specific phenological stage of the year in which ecosystem vulnerability to a certain climatic condition occurs.
How to cite.
Vogel, J., Paton, E., and Aich, V.: Seasonal ecosystem vulnerability to climatic anomalies in the Mediterranean, Biogeosciences, 18, 5903–5927, https://doi.org/10.5194/bg-18-5903-2021, 2021.
Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
10.25932/publishup-55497
urn:nbn:de:kobv:517-opus4-554974
1866-8372
Vogel, Johannes
<a href="http://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/55498">Bibliographieeintrag der Originalveröffentlichung/Quelle</a>
Version of record
false
true
CC-BY - Namensnennung 4.0 International
Johannes Joscha Vogel
Eva Nora Paton
Valentin Aich
Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
1252
Geowissenschaften
open_access
Referiert
Institut für Umweltwissenschaften und Geographie
Green Open-Access
Universität Potsdam
https://publishup.uni-potsdam.de/files/55497/pmnr1252.pdf