scholarly journals Climate change alters low flows in Europe under a 1.5, 2, and 3 degree global warming

2017 ◽  
Author(s):  
Andreas Marx ◽  
Rohini Kumar ◽  
Stephan Thober ◽  
Matthias Zink ◽  
Niko Wanders ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
River Flow ◽  
Northern Region ◽  
Model Ensemble ◽  
Large Variability ◽  
Daily Streamflow ◽  
Low Flows ◽  
Future Global Warming ◽  
The Mediterranean

Abstract. There is growing evidence that climate change will alter water availability in Europe. Here, we investigate how hydrological low flows are affected under different levels of future global warming (i.e., 1.5, 2 and 3 K). The analysis is based on a multi-model ensemble of 45 hydrological simulations based on three RCPs (rcp2p6, rcp6p0, rcp8p5), five CMIP5 GCMs (GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR, MIROC-ESM-CHEM, NorESM1-M) and three state-of-the-art hydrological models (HMs: mHM, Noah-MP, and PCR-GLOBWB). High resolution model results are available at the unprecedented spatial resolution of 5 km across the pan-European domain at daily temporal resolution. Low river flow is described as the percentile of daily streamflow that is exceeded 90 % of the time. It is determined separately for each GCM/HM combinations and the warming scenarios. The results show that the change signal amplifies with increasing warming levels. Low flows decrease in the Mediterranean while they increase in the Alpine and Northern regions. In the Mediterranean, the level of warming amplifies the signal from −12 % under 1.5 K to −35 % under 3 K global warming largely due to the projected decreases in annual precipitation. In contrast, the signal is amplified from +22 % (1.5 K) to +45 % (3 K) in the Alpine region because of the reduced snow melt contribution. The changes in low flows are significant for regions with relatively large change signals and under higher levels of warming. Nevertheless, it is not possible to distinguish climate induced differences in low flows between 1.5 and 2 K warming because of the large variability inherent in the multi-model ensemble. The contribution by the GCMs to the uncertainty in the model results is generally higher than the one by the HMs. However, the uncertainty due to HMs cannot be neglected. In the Alpine and Northern region as well as the Mediterranean, the uncertainty contribution by the HMs is partly higher than those by the GCMs due to different representations of processes such as snow, soil moisture and evapotranspiration.

scholarly journals Climate change alters low flows in Europe under global warming of 1.5, 2, and 3 °C

2018 ◽  
Vol 22 (2) ◽  
pp. 1017-1032 ◽  
Author(s):  
Andreas Marx ◽  
Rohini Kumar ◽  
Stephan Thober ◽  
Oldrich Rakovec ◽  
Niko Wanders ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
General Circulation ◽  
Snow Accumulation ◽  
Low Flow ◽  
Model Ensemble ◽  
Daily Streamflow ◽  
Low Flows ◽  
Future Global Warming ◽  
The Mediterranean

Abstract. There is growing evidence that climate change will alter water availability in Europe. Here, we investigate how hydrological low flows are affected under different levels of future global warming (i.e. 1.5, 2, and 3 K with respect to the pre-industrial period) in rivers with a contributing area of more than 1000 km2. The analysis is based on a multi-model ensemble of 45 hydrological simulations based on three representative concentration pathways (RCP2.6, RCP6.0, RCP8.5), five Coupled Model Intercomparison Project Phase 5 (CMIP5) general circulation models (GCMs: GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR, MIROC-ESM-CHEM, NorESM1-M) and three state-of-the-art hydrological models (HMs: mHM, Noah-MP, and PCR-GLOBWB). High-resolution model results are available at a spatial resolution of 5 km across the pan-European domain at a daily temporal resolution. Low river flow is described as the percentile of daily streamflow that is exceeded 90 % of the time. It is determined separately for each GCM/HM combination and warming scenario. The results show that the low-flow change signal amplifies with increasing warming levels. Low flows decrease in the Mediterranean region, while they increase in the Alpine and Northern regions. In the Mediterranean, the level of warming amplifies the signal from −12 % under 1.5 K, compared to the baseline period 1971–2000, to −35 % under global warming of 3 K, largely due to the projected decreases in annual precipitation. In contrast, the signal is amplified from +22 (1.5 K) to +45 % (3 K) in the Alpine region due to changes in snow accumulation. The changes in low flows are significant for regions with relatively large change signals and under higher levels of warming. However, it is not possible to distinguish climate-induced differences in low flows between 1.5 and 2 K warming because of (1) the large inter-annual variability which prevents distinguishing statistical estimates of period-averaged changes for a given GCM/HM combination, and (2) the uncertainty in the multi-model ensemble expressed by the signal-to-noise ratio. The contribution by the GCMs to the uncertainty in the model results is generally higher than the one by the HMs. However, the uncertainty due to HMs cannot be neglected. In the Alpine, Northern, and Mediterranean regions, the uncertainty contribution by the HMs is partly higher than those by the GCMs due to different representations of processes such as snow, soil moisture and evapotranspiration. Based on the analysis results, it is recommended (1) to use multiple HMs in climate impact studies and (2) to embrace uncertainty information on the multi-model ensemble as well as its single members in the adaptation process.

Evidence of river flow regulation loss over time in the Magdalena river basin 

2021 ◽  
Author(s):  
Diver E. Marín ◽  
Juan F. Salazar ◽  
José A. Posada-Marín
Keyword(s):  
Climate Change ◽  
Environmental Change ◽  
River Basin ◽  
River Flow ◽  
Southern Oscillation ◽  
Scaling Theory ◽  
Scaling Properties ◽  
Low Flows ◽  
High Flows ◽  
Magdalena River

<p>Some of the main problems in hydrological sciences are related to how and why river flows change as a result of environmental change, and what are the corresponding implications for society. This has been described as the Panta Rhei context, which refers to the challenge of understanding and quantifying hydrological dynamics in a changing environment, i.e. under the influence of non-stationary effects. The river flow regime in a basin is the result of a complex aggregation process that has been studied by the scaling theory, which allows river basins to be classified as regulated or unregulated and to identify a critical threshold between these states. Regulation is defined here as the basin’s capacity to either dampen high flows or to enhance low flows. This capacity depends on how basins store and release water through time, which in turn depends on many processes that are highly dynamic and sensitive to environmental change. Here we focus on the Magdalena river basin in northwestern South America, which is the main basin for water and energy security in Colombia, and at the same time, it has been identified as one of the most vulnerable regions to be affected by climate change. Building upon some of our previous studies, here we use data analysis to study the evolution of regulation in the Magdalena basin for 1992-2015 based on the scaling theory for extreme flows. In contrast to most previous studies, here we focus on the scaling properties of events rather than on long term averages. We discuss possible relations between changes in the scaling properties and environmental factors such as climate variability, climate change, and land use/land cover change, as well as the potential implications for water security in the country. Our results show that, during the last few decades, the Magdalena river basin has maintained its capacity to regulate low flows (i.e. amplification) whereas it has been losing its capacity to regulate high flows (i.e. dampening), which could be associated with the occurrence of the extremes phases of  El Niño Southern Oscillation (ENSO) and anthropogenic effects, mainly deforestation. These results provide foundations for using the scaling laws as empirical tools for understanding temporal changes of hydrological regulation and simultaneously generate useful scientific evidence that allows stakeholders to take decisions related to water management in the Magdalena river basin in the context of environmental change.</p>

scholarly journals How will climate change modify river flow regimes in Europe?

2013 ◽  
Vol 17 (1) ◽  
pp. 325-339 ◽  
Author(s):  
C. Schneider ◽  
C. L. R. Laizé ◽  
M. C. Acreman ◽  
M. Flörke
Keyword(s):  
Climate Change ◽  
River Flow ◽  
Anthropogenic Impacts ◽  
Flow Characteristics ◽  
Flow Regimes ◽  
Temperate Climate ◽  
Climate Zone ◽  
Natural Flow ◽  
The Mediterranean ◽  
Boreal Climate

Abstract. Worldwide, flow regimes are being modified by various anthropogenic impacts and climate change induces an additional risk. Rising temperatures, declining snow cover and changing precipitation patterns will interact differently at different locations. Consequently, in distinct climate zones, unequal consequences can be expected in matters of water stress, flood risk, water quality, and food security. In particular, river ecosystems and their vital ecosystem services will be compromised as their species richness and composition have evolved over long time under natural flow conditions. This study aims at evaluating the exclusive impacts of climate change on river flow regimes in Europe. Various flow characteristics are taken into consideration and diverse dynamics are identified for each distinct climate zone in Europe. In order to simulate present-day natural flow regimes and future flow regimes under climate change, the global hydrology model WaterGAP3 is applied. All calculations for current and future conditions (2050s) are carried out on a 5' × 5' European grid. To address uncertainty, bias-corrected climate forcing data of three different global climate models are used to drive WaterGAP3. Finally, the hydrological alterations of different flow characteristics are quantified by the Indicators of Hydrological Alteration approach. Results of our analysis indicate that on the European scale, climate change can be expected to modify flow regimes remarkably. This is especially the case in the Mediterranean (due to drier conditions with reduced precipitation across the year) and in the boreal climate zone (due to reduced snowmelt, increased precipitation, and strong temperature rises). In the temperate climate zone, impacts increase from oceanic to continental. Regarding single flow characteristics, strongest impacts on timing were found for the boreal climate zone. This applies for both high and low flows. Flow magnitudes, in turn, will be predominantly altered in the Mediterranean but also in the Northern climates. At the end of this study, typical future flow regimes under climate change are illustrated for each climate zone.

Intensification of extreme snowfall under future warming

2021 ◽  
Author(s):  
Lennart Quante ◽  
Sven Willner ◽  
Robin Middelanis ◽  
Anders Levermann
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Observational Data ◽  
Climate Models ◽  
Hydrological Cycle ◽  
Freezing Point ◽  
Model Ensemble ◽  
Northern Latitudes ◽  
Coupled Climate Models ◽  
Future Warming

<p>Due to climate change the frequency and character of precipitation are changing as the hydrological cycle intensifies. With regards to snowfall, global warming thereby has two opposing influences. Increasing humidity enables potentially intense snowfall, whereas warming temperatures decrease the likelihood of snowfall in the first place. Here we show an intensification of extreme snowfall under future warming, which is robust across all global coupled climate models when they are bias-corrected with observational data. While mean daily snowfall decreases drastically in the model ensemble, both the 99th and the 99.9th percentiles of daily snowfall increase strongly in the next decades. Additionally, the magnitude of high snowfall events increases, which is likely to pose considerable challenge to municipalities in mid to high northern latitudes. We propose that the almost unchanged occurrence of temperatures just below the freezing point of water in combination with the strengthening of the hydrological cycle enables this intensification of extreme snowfall. Thus extreme snowfall events are likely to become an increasingly important impact of climate change on society in the next decades.</p>

Spatiotemporal Changes in Headwater Flow Contributions to Major Rivers of Germany under Changing Climate

2020 ◽  
Author(s):  
Akash Koppa ◽  
Thomas Remke ◽  
Stephan Thober ◽  
Oldrich Rakovec ◽  
Sebastian Müller ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Soil Moisture ◽  
Climate Models ◽  
Climate Model ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Model Ensemble ◽  
Hydrologic Models ◽  
River Temperature

<p>Headwater systems are a major source of water, sediments, and nutrients (including nitrogen and carbon di-oxide) for downstream aquatic, riparian, and inland ecosystems. As precipitation changes are expected to exhibit considerable spatial variability in the future, we hypothesize that headwater contribution to major rivers will also change significantly. Quantifying these changes is essential for developing effective adaptation and mitigation strategies against climate change. However, the lack of hydrologic projections at high resolutions over large domains have hindered attempts to quantify climate change impacts on headwater systems.</p><p>Here, we overcome this challenge by developing an ensemble of hydrologic projections at an unprecedented resolution (1km) for Germany. These high resolution projections are developed within the framework of the Helmholtz Climate Initiative (https://www.helmholtz.de/en/current-topics/the-initiative/climate-research/). Our modeling chain consists of the following four components:</p><p><strong>Climate Modeling:</strong> We statistically downscale and bias-adjust climate change scenarios from three representative concentration pathway (RCP) scenarios derived from the EURO-CORDEX ensemble - 2.6, 4.5, and 8.5 to a horizontal resolution of 1km over Germany (i.e, a total of 75 ensemble members). The EURO-CORDEX ensemble is generated by dynamically downscaling CMIP-5 general circulation models (GCM) using regional climate models (RCMs). <strong>Hydrologic Modeling:</strong> To account for model structure uncertainty, the climate model projections are used as forcings for three spatially distributed hydrologic models - a) the mesocale Hydrologic model (mHM), b) Noah-MP, and c) HTESSEL. The outputs that will be generated in the study are soil moisture, evapotranspiration, snow water equivalent, and runoff. <strong>Streamflow Routing:</strong> To minimize uncertainty from river routing schemes, we use the multiscale routing model (mRM v1.0) to route runoff from all the three models. <strong>River Temperature Modeling:</strong> A novel river temperature model is used to quantify the changes in river temperature due to anthropogenic warming.</p><p>The 225-member ensemble streamflow outputs (75 climate model members and 3 hydrologic models) are used to quantify the changes in the contribution of headwater watersheds to all the major rivers in Germany. Finally, we analyze changes in soil moisture, snow melt, and river temperature and their implications for headwater contributions. Previously, a high-resolution (5km) multi-model ensemble for climate change projections has been created within the EDgE project<strong><sup>1,2,3,4</sup></strong>. The newly created projections in this project will be compared against those created in the EDgE project.  The ensemble used in this project will profit from the higher resolution of the regional climate models that provide a more detailed land orography.</p><p><strong>References</strong></p><p><strong>[1] </strong>Marx,<em> A. et al. (2018). Climate change alters low flows in Europe under global warming of 1.5, 2, and 3 C. Hydrology and Earth System Sciences, 22(2), 1017-1032.</em></p><p><strong>[2]</strong><em> Samaniego, L. et al. (2019). Hydrological forecasts and projections for improved decision-making in the water sector in Europe. Bulletin of the American Meteorological Society.</em></p><p><strong>[3]</strong> Samaniego,<em> L. and Thober, S., et al. (2018). Anthropogenic warming exacerbates European soil moisture droughts. Nature Climate Change, 8(5), 421.</em></p><p><strong>[4]</strong> Thober,<em> S. et al. (2018). Multi-model ensemble projections of European river floods and high flows at 1.5, 2, and 3 degrees global warming. Environmental Research Letters, 13(1), 014003.</em></p><p> </p><p> </p><p> </p>

scholarly journals Mekong River flow and hydrological extremes under climate change

2016 ◽  
Vol 20 (7) ◽  
pp. 3027-3041 ◽  
Author(s):  
Long Phi Hoang ◽  
Hannu Lauri ◽  
Matti Kummu ◽  
Jorma Koponen ◽  
Michelle T. H. van Vliet ◽  
...  
Keyword(s):  
Climate Change ◽  
River Flow ◽  
High Flow ◽  
Mekong River ◽  
Low Flow ◽  
Future Climate Change ◽  
Climate Projections ◽  
Low Flows ◽  
Hydrological Extremes ◽  
Hydrological Impact

Abstract. Climate change poses critical threats to water-related safety and sustainability in the Mekong River basin. Hydrological impact signals from earlier Coupled Model Intercomparison Project phase 3 (CMIP3)-based assessments, however, are highly uncertain and largely ignore hydrological extremes. This paper provides one of the first hydrological impact assessments using the CMIP5 climate projections. Furthermore, we model and analyse changes in river flow regimes and hydrological extremes (i.e. high-flow and low-flow conditions). In general, the Mekong's hydrological cycle intensifies under future climate change. The scenario's ensemble mean shows increases in both seasonal and annual river discharges (annual change between +5 and +16 %, depending on location). Despite the overall increasing trend, the individual scenarios show differences in the magnitude of discharge changes and, to a lesser extent, contrasting directional changes. The scenario's ensemble, however, shows reduced uncertainties in climate projection and hydrological impacts compared to earlier CMIP3-based assessments. We further found that extremely high-flow events increase in both magnitude and frequency. Extremely low flows, on the other hand, are projected to occur less often under climate change. Higher low flows can help reducing dry season water shortage and controlling salinization in the downstream Mekong Delta. However, higher and more frequent peak discharges will exacerbate flood risks in the basin. Climate-change-induced hydrological changes will have important implications for safety, economic development, and ecosystem dynamics and thus require special attention in climate change adaptation and water management.

scholarly journals Effect of climate change on the spatial distribution and cork production of Quercus suber L., the risk of exclusion by the Aleppo pine expansion, and management practices to protect Q. suber habitat: A review

2021 ◽  
Vol 49 (1) ◽  
pp. 12218
Author(s):  
Kaouther MECHERGUI ◽  
Wahbi JAOUADI ◽  
Amal S. ALTAMIMI ◽  
Souheila NAGHMOUCHI ◽  
Youssef AMMARI
Keyword(s):  
Climate Change ◽  
Spatial Distribution ◽  
Management Practices ◽  
Quercus Suber ◽  
Cork Oak ◽  
Aleppo Pine ◽  
Cork Production ◽  
Future Global Warming ◽  
The Future ◽  
The Mediterranean

Climate change represents an important challenge for forest management and the silviculture of stands and it is known that climate change will have complex effects on cork oak forest ecosystems. North Africa and the Mediterranean basin are especially vulnerable to climate change. Under the effect of climate change, cork oak will disappear from a large area in the future, and the rest will migrate to higher altitudes and latitudes. This study aimed to evaluate the effect of climate change on the spatial distribution of Quercus suber L. and cork production in the Mediterranean area, and the risk of its exclusion by the Aleppo pine (Pinus halepensis Mill.) expansion. The literature review showed that up to 40% of current environmentally suitable areas for cork oak may be lost by 2070, mainly in northern Africa and the southern Iberian Peninsula. Temperature directly influences atmospheric evaporative demand and should affect cork productivity. Precipitation is the main factor that positively influences cork growth and several authors have confirmed the negative effect of drought on this growth. Currently, cork oak habitats are colonized in several places mainly by the Aleppo pine. Under climate change, Aleppo pine is projected to occupy higher altitude sites and several authors have predicted that current and future global warming will have a positive influence on Aleppo pine growth in wet sites. In the future and under climate change, there is a strong possibility that the Aleppo pine will colonize cork oak habitat. Finally, we proposed management practices to protect cork oak against climate change and Aleppo pine expansion.

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