scholarly journals Independence of Future Changes of River Runoff in Europe from the Pathway to Global Warming

Climate ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 22
Author(s):  
Lorenzo Mentaschi ◽  
Lorenzo Alfieri ◽  
Francesco Dottori ◽  
Carmelo Cammalleri ◽  
Berny Bisselink ◽  
...  
Keyword(s):  
Global Warming ◽  
Climate Model ◽  
Statistical Significance ◽  
Regional Climate ◽  
Climate Impact ◽  
Major Loss ◽  
Floods And Droughts ◽  
The Difference ◽  
Projected Changes ◽  
Time Frames

The outcomes of the 2015 Paris Agreement triggered a number of climate impact assessments, such as for floods and droughts, to focus on future time frames corresponding to the years of reaching specific levels of global warming. Yet, the links between the timing of the warming levels and the corresponding greenhouse gas concentration pathways to reach them remain poorly understood. To address this gap, we compared projected changes of annual mean, extreme high, and extreme low river discharges in Europe at 1.5 °C and 2 °C under Representative Concentration Pathways RCP8.5 and RCP4.5 from an ensemble of regional climate model (RCM) simulations. The statistical significance of the difference between the two scenarios for both warming levels was then evaluated. The results show that in the majority of Europe (>95% of the surface area for the annual mean discharge, >98% for high and low extremes), the changes projected in the two pathways were statistically indistinguishable. These results suggest that in studies of changes at global warming levels, the projections of the two pathways can be merged into a single ensemble without major loss of information. With regard to the uncertainty of the unified ensemble, the findings show that the projected changes of annual mean, extreme high, and extreme low river discharge were statistically significant in large portions of Europe.

scholarly journals Independence of Future Changes of River Runoff in Europe from the Pathway to Global Warming

2020 ◽  
Author(s):  
Lorenzo Mentaschi ◽  
Lorenzo Alfieri ◽  
Francesco Dottori ◽  
Carmelo Cammalleri ◽  
Berny Bisselink ◽  
...  
Keyword(s):  
Global Warming ◽  
Climate Model ◽  
Statistical Significance ◽  
Regional Climate ◽  
Climate Impact ◽  
Major Loss ◽  
Floods And Droughts ◽  
The Difference ◽  
Projected Changes ◽  
Time Frames

The outcomes of the 2015 Paris Agreement triggered a number of climate impact assessments, such as for floods and droughts, to focus on future time frames corresponding to the years of reaching specific levels of global warming. Yet, the links between the timing of the warming levels and the corresponding greenhouse gas concentration pathways to reach them, remain poorly understood. To address this gap, we compare projected changes of annual mean, extreme high and extreme low river discharges in Europe at 1.5°C and 2°C under scenarios RCP8.5 and RCP4.5 from an ensemble of Regional Climate Model (RCM) simulations. The statistical significance of the difference between the two scenarios for both warming levels is then evaluated. Results show that in the majority of Europe (>95% of the surface area for the annual mean discharge, >98% for high and low extremes), the changes projected in the two pathways are statistically indistinguishable. These results suggest that in studies of changes at specific warming levels the projections of the two pathways can be merged into a single ensemble without major loss of information. With regard to the uncertainty of the unified ensemble, findings show that the projected changes of annual mean, extreme high and extreme low river discharge are statistically significant in large portions of Europe.

scholarly journals Independence of Future Changes of River Runoff in Europe from the Pathway to Global Warming

2019 ◽  
Author(s):  
Lorenzo Mentaschi ◽  
Lorenzo Alfieri ◽  
Francesco Dottori ◽  
Carmelo Cammalleri ◽  
Berny Bisselink ◽  
...  
Keyword(s):  
Global Warming ◽  
Climate Model ◽  
Statistical Significance ◽  
Regional Climate ◽  
Climate Impact ◽  
Major Loss ◽  
Floods And Droughts ◽  
The Difference ◽  
Projected Changes ◽  
Time Frames

The outcomes of the 2015 Paris Agreement triggered a number of climate impact assessments, such as for floods and droughts, to focus on future time frames corresponding to the years of reaching specific levels of global warming. Yet, the links between the timing of the warming levels and the corresponding greenhouse gas concentration pathways to reach them, remain poorly understood. To address this gap, we compare projected changes of annual mean, extreme high and extreme low river discharges in Europe at 1.5° and 2° under scenarios RCP8.5 and RCP4.5 from an ensemble of Regional Climate Model (RCM) simulations. The statistical significance of the difference between the two scenarios for both warming levels is then evaluated. Results show that in the majority of Europe (>95% for the annual mean discharge, >98% for high and low extremes), the changes projected in the two pathways are statistically indistinguishable. These results suggest that in studies of changes at specific warming levels the projections of the two pathways can be merged into a single ensemble without major loss of information. With regard to the uncertainty of the unified ensemble, findings show that the projected changes of annual mean, extreme high and extreme low river discharge are statistically significant in large portions of Europe.

On the independence from the emission pathway of the projected changes of river runoff

2020 ◽  
Author(s):  
Lorenzo Mentaschi ◽  
Lorenzo Alfieri ◽  
Francesco Dottori ◽  
Carmelo Cammalleri ◽  
Berny Bisselink ◽  
...  
Keyword(s):  
Climate Model ◽  
Statistical Significance ◽  
Regional Climate ◽  
Time Frame ◽  
Climate Impact ◽  
The Other ◽  
Minor Role ◽  
Emission Pathway ◽  
Projected Change ◽  
Projected Changes

<p><span>After the Paris Agreement of 2015 many studies on climate impact assessment, e.g. of floods, water resources and droughts, focused on understanding the projected changes at the time frame when a specific warming level is reached. The results of these studies assume that the pathway to reach a certain greenhouse concentration and corresponding warming level plays a minor role in the change of the physical variables that define the hazard. However, this hypothesis should be verified for each variable, as the links between the timing of the warming levels and the projected changes of the geophysical variables are not yet fully understood. To address this gap, in this contribution we compared the projected changes of annual mean, extreme high and extreme low river discharges in Europe at 1.5°C and 2°C under scenarios RCP8.5 and RCP4.5 from an ensemble of Regional Climate Model simulations. The statistical significance of the difference between the two scenarios for both warming levels has been then evaluated versus the other sources of uncertainty, through an Analysis of Variance (ANOVA). The results show that in the majority of Europe (>95% of the surface area for the annual mean discharge, >98% for high and low extremes), the differences in the changes projected in the two pathways are statistically small. These results suggest that in studies of changes at specific warming levels the projections of the two pathways can be merged into a single ensemble without major loss of information. With regard to the uncertainty of the merged ensemble, findings show that the projected changes of annual mean, extreme high and extreme low river discharges are statistically significant in large portions of Europe. Merging the 2 pathways comes with a two-fold advantage with respect to the separate treatment of the 2 scenarios. On the one hand, it improves the estimation of the statistical significance of the projected change, by increasing its size and by better taking into account the pathway-related uncertainty (the emission pathways are set ex-ante as a hypothesis for the CMIP experiment, and the related uncertainty is usually neglected). On the other hand, a multi-pathway ensemble can simplify the discussion of the projected changes by removing from the analysis the dependency from the emission pathway, and making the results clearer and more understandable by a non-scientific public.</span></p>

scholarly journals 2 °C vs. High Warming: Transitions to Flood-Generating Mechanisms across Canada

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1494
Author(s):  
Bernardo Teufel ◽  
Laxmi Sushama
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Climate Model ◽  
Regional Climate ◽  
Adaptation Measures ◽  
Relative Contribution ◽  
Late 21St Century ◽  
Transient Climate Change ◽  
Projected Changes ◽  
Change Mitigation

Fluvial flooding in Canada is often snowmelt-driven, thus occurs mostly in spring, and has caused billions of dollars in damage in the past decade alone. In a warmer climate, increasing rainfall and changing snowmelt rates could lead to significant shifts in flood-generating mechanisms. Here, projected changes to flood-generating mechanisms in terms of the relative contribution of snowmelt and rainfall are assessed across Canada, based on an ensemble of transient climate change simulations performed using a state-of-the-art regional climate model. Changes to flood-generating mechanisms are assessed for both a late 21st century, high warming (i.e., Representative Concentration Pathway 8.5) scenario, and in a 2 °C global warming context. Under 2 °C of global warming, the relative contribution of snowmelt and rainfall to streamflow peaks is projected to remain close to that of the current climate, despite slightly increased rainfall contribution. In contrast, a high warming scenario leads to widespread increases in rainfall contribution and the emergence of hotspots of change in currently snowmelt-dominated regions across Canada. In addition, several regions in southern Canada would be projected to become rainfall dominated. These contrasting projections highlight the importance of climate change mitigation, as remaining below the 2 °C global warming threshold can avoid large changes over most regions, implying a low likelihood that expensive flood adaptation measures would be necessary.

scholarly journals Hydrological Climate-Impact Projections for the Rhine River: GCM–RCM Uncertainty and Separate Temperature and Precipitation Effects*

2014 ◽  
Vol 15 (2) ◽  
pp. 697-713 ◽  
Author(s):  
Thomas Bosshard ◽  
Sven Kotlarski ◽  
Massimiliano Zappa ◽  
Christoph Schär
Keyword(s):  
Climate Change ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Regional Climate ◽  
Climate Impact ◽  
Rhine River ◽  
Supply Source ◽  
Rhine Basin ◽  
Projected Changes ◽  
The Impact

Abstract Climate change is expected to affect the hydrological cycle, with considerable impacts on water resources. Climate-induced changes in the hydrology of the Rhine River (Europe) are of major importance for the riparian countries, as the Rhine River is the most important European waterway, serves as a freshwater supply source, and is prone to floods and droughts. Here regional climate model data from the Ensemble-Based Predictions of Climate Changes and their Impacts (ENSEMBLES) project is used to drive the hydrological model Precipitation–Runoff–Evapotranspiration–Hydrotope (PREVAH) and to assess the impact of climate change on the hydrology in the Rhine basin. Results suggest increases in monthly mean runoff during winter and decreases in summer. At the gauge Cologne and for the period 2070–99 under the A1B scenario of the Special Report on Emissions Scenarios, projected decreases in summer vary between −9% and −40% depending on the climate model used, while increases in winter are in the range of +4% to +51%. These projected changes in mean runoff are generally consistent with earlier studies, but the derived spread in the runoff projections appears to be larger. It is demonstrated that temperature effects (e.g., through altered snow processes) dominate in the Alpine tributaries, while precipitation effects dominate in the lower portion of the Rhine basin. Analyses are also presented for selected extreme runoff indices.

scholarly journals The response of precipitation characteristics to global warming from climate projections

2019 ◽  
Vol 10 (1) ◽  
pp. 73-89 ◽  
Author(s):  
Filippo Giorgi ◽  
Francesca Raffaele ◽  
Erika Coppola
Keyword(s):  
Global Warming ◽  
Climate Model ◽  
Regional Climate ◽  
Climate Projections ◽  
Potential Predictability ◽  
Precipitation Characteristics ◽  
Dry Spell ◽  
The Difference ◽  
Light Precipitation ◽  
Precipitation Events

Abstract. We revisit the issue of the response of precipitation characteristics to global warming based on analyses of global and regional climate model projections for the 21st century. The prevailing response we identify can be summarized as follows: increase in the intensity of precipitation events and extremes, with the occurrence of events of “unprecedented” magnitude, i.e., a magnitude not found in the present-day climate; decrease in the number of light precipitation events and in wet spell lengths; and increase in the number of dry days and dry spell lengths. This response, which is mostly consistent across the models we analyzed, is tied to the difference between precipitation intensity responding to increases in local humidity conditions and circulations, especially for heavy and extreme events, and mean precipitation responding to slower increases in global evaporation. These changes in hydroclimatic characteristics have multiple and important impacts on the Earth's hydrologic cycle and on a variety of sectors. As examples we investigate effects on potential stress due to increases in dry and wet extremes, changes in precipitation interannual variability, and changes in the potential predictability of precipitation events. We also stress how the understanding of the hydroclimatic response to global warming can provide important insights into the fundamental behavior of precipitation processes, most noticeably tropical convection.

scholarly journals Diverging hydrological drought traits over Europe with global warming

2020 ◽  
Author(s):  
Carmelo Cammalleri ◽  
Gustavo Naumann ◽  
Lorenzo Mentaschi ◽  
Bernard Bisselink ◽  
Emiliano Gelati ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Agricultural Land ◽  
Climate Model ◽  
Regional Climate ◽  
Low Flow ◽  
Flow Index ◽  
Drought Hazard ◽  
The Mediterranean ◽  
Projected Changes

Abstract. Climate change is anticipated to alter the demand and supply of water at the earth's surface. Since many societal impacts from a lack of water happen under drought conditions, it is important to understand how droughts may develop with climate change. This study shows how hydrological droughts will change across Europe with increasing global warming levels (GWL of 1.5, 2 and 3 K above preindustrial temperature). We employ a low-flow index derived from river discharge simulations of a spatially-distributed physically-based hydrological and water use model, which was forced with a large ensemble of regional climate model projections under a high emissions (RCP8.5) and moderate mitigation (RCP4.5) pathway. Different traits of drought, including severity, duration and frequency, were investigated. The projected changes in these treats identify four main sub-regions in Europe that are characterized by somehow homogeneous and distinct behaviours with a clear southwest/northeast contrast. The Mediterranean and Boreal sub-regions of Europe show strong, but opposite, changes at all three GWLs, with the former area mostly interested by stronger droughts (with larger differences at 3 K) while the latter sees a reduction in droughts. In the Atlantic and Continental sub-regions the changes are less marked and characterized by a larger uncertainty, especially at the 1.5 and 2 K GWLs. Combining the projections in drought hazard with population and agricultural information shows that with 3 K global warming an additional 11 million people and 4.5 million ha of agricultural land will be exposed to droughts every year, on average. These are mostly located in the Mediterranean and Atlantic regions of Europe.

scholarly journals Projected changes to extreme freezing precipitation and design ice loads over North America based on a large ensemble of Canadian regional climate model simulations

2018 ◽  
Author(s):  
Dae Il Jeong ◽  
Alex J. Cannon ◽  
Xuebin Zhang
Keyword(s):  
Global Warming ◽  
Wind Speed ◽  
North America ◽  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Ice Accretion ◽  
Ice Loads ◽  
Upper Level ◽  
Projected Changes

Abstract. Atmospheric ice accretion caused by freezing precipitation (FP) can lead to severe damage and failure of buildings and infrastructure. This study investigates projected changes to extreme ice loads – those used to design infrastructure over North America (NA) – for future periods of specified global mean temperature change (GMTC), relative to a recent 1986–2016 period, using a large 50 member initial condition ensemble of the CanRCM4 regional climate model driven by CanESM2 under the RCP8.5 scenario. The analysis is based on three-hourly ice accretions on horizontal, vertical, and radial surfaces calculated based on FP diagnosed by the offline Bourgouin algorithm as well as wind speed during FP. The CanRCM4 ensemble projects an increase in future design ice loads for most of northern NA and decreases for most of southern NA and some northeastern coastal regions. These changes are mainly caused by regional increases in future upper level and surface temperatures associated with global warming. Projected changes in design ice thickness are also affected by changes in future precipitation intensity and surface wind speed. Changes in upper level and surface temperature conditions for FP occurrence in CanRCM4 are in broad agreement with those from nine global climate models, but display regional differences under the same level of global warming, indicating that a larger multi-model, multi-scenario ensemble may be needed to better account for additional sources of structural and scenario uncertainty. Increases in ice accretion for latitudes higher than 40° N are substantial and would have clear implications for future building and infrastructure design.

scholarly journals The response of precipitation characteristics to global warming from global and regional climate projections

2018 ◽  
Author(s):  
Filippo Giorgi ◽  
Francesca Raffaele ◽  
Erika Coppola
Keyword(s):  
Global Warming ◽  
Climate Model ◽  
Regional Climate ◽  
Climate Projections ◽  
Potential Predictability ◽  
Precipitation Characteristics ◽  
Dry Spell ◽  
The Difference ◽  
Regional Climate Projections ◽  
Precipitation Events

Abstract. We revisit the issue of the response of the precipitation characteristics to global warming based on analyses of global and regional climate model projections for the 21st century. The prevailing response we identify can be summarized as follows: increase in the intensity of precipitation events and extremes, with the occurrence of events of unprecedented magnitude, i.e. magnitude not found in present day climate; decrease in the number of light precipitation events and in wet spell lengths; increase in the number of dry days and dry spell lengths. This response, which is mostly consistent across the models we analized, is tied to the difference between precipitation intensity responding to increases in local humidity conditions, especially for heavy and extreme events, and mean precipitation responding to slower increases in global evaporation. These changes in hydroclimatic characteristics have multiple and important impacts on the Earth's hydrologic cycle and on a variety of sectors, and as examples we investigate effects on the potential stress due to increases in dry and wet extremes, changes in precipitation interannual variability and changes in potential predictability of precipitation events. We also stress how the understanding of the hydroclimatic response to global warming can shed important insights into the fundamental behavior of precipitation processes, most noticeably tropical convection.

scholarly journals Projected changes to extreme freezing precipitation and design ice loads over North America based on a large ensemble of Canadian regional climate model simulations

2019 ◽  
Vol 19 (4) ◽  
pp. 857-872 ◽  
Author(s):  
Dae Il Jeong ◽  
Alex J. Cannon ◽  
Xuebin Zhang
Keyword(s):  
Global Warming ◽  
Wind Speed ◽  
North America ◽  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Ice Accretion ◽  
Ice Loads ◽  
Upper Level ◽  
Projected Changes

Abstract. Atmospheric ice accretion caused by freezing precipitation (FP) can lead to severe damage and the failure of buildings and infrastructure. This study investigates projected changes to extreme ice loads – those used to design infrastructure over North America (NA) – for future periods of specified global mean temperature change (GMTC), relative to the recent 1986–2016 period, using a large 50-member initial-condition ensemble of the CanRCM4 regional climate model, driven by CanESM2 under the RCP8.5 scenario. The analysis is based on 3-hourly ice accretions on horizontal, vertical and radial surfaces calculated based on FP diagnosed by the offline Bourgouin algorithm and wind speed during FP. The CanRCM4 ensemble projects an increase in future design ice loads for most of northern NA and decreases for most of southern NA and some northeastern coastal regions. These changes are mainly caused by regional increases in future upper-level and surface temperatures associated with global warming. Projected changes in design ice thickness are also affected by changes in future precipitation intensity and surface wind speed. Changes in upper-level and surface temperature conditions for FP occurrence in CanRCM4 are in broad agreement with those from nine global climate models but display regional differences under the same level of global warming, indicating that a larger multi-model, multi-scenario ensemble may be needed to better account for additional sources of structural and scenario uncertainty. Increases in ice accretion for latitudes higher than 40∘ N are substantial and would have clear implications for future building and infrastructure design.

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