Regional climate change in Portugal: precipitation variability associated with large-scale atmospheric circulation

Abstract. Under certain hydrological conditions it is possible for spring flow in karst systems to be reversed. When this occurs, the resulting invasion by surface water, i.e. the backflooding, represents a serious threat to groundwater quality because the surface water could well be contaminated. Here we examine the possible impact of future climate change on the occurrences of backflooding in a specific karst system, having first established the occurrence of such events in the selected study area over the past 40 yr. It would appear that backflooding has been more frequent since the 1980s, and that it is apparently linked to river flow variability on the pluri-annual scale. The avenue that we adopt here for studying recent and future variations of these events is based on a downscaling algorithm relating large-scale atmospheric circulation to local precipitation spatial patterns. The large-scale atmospheric circulation is viewed as a set of quasi-stationary and recurrent states, called weather types, and its variability as the transition between them. Based on a set of climate model projections, simulated changes in weather-type occurrence for the end of the century suggests that backflooding events can be expected to decrease in 2075–2099. If such is the case, then the potential risk for groundwater quality in the area will be greatly reduced compared to the current situation. Finally, our results also show the potential interest of the weather-type based downscaling approach for examining the impact of climate change on hydrological systems.

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Storyline approach to the construction of regional climate change information

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2019.0013 ◽

2019 ◽

Vol 475 (2225) ◽

pp. 20190013 ◽

Cited By ~ 16

Author(s):

Theodore G. Shepherd

Keyword(s):

Climate Change ◽

Atmospheric Circulation ◽

Regional Climate ◽

Regional Scale ◽

Regional Climate Change ◽

Climate Impacts ◽

Climate Projections ◽

Ethical Implications ◽

Climate Change Information ◽

The Impact

Climate science seeks to make statements of confidence about what has happened, and what will happen (conditional on scenario). The approach is effective for the global, thermodynamic aspects of climate change, but is ineffective when it comes to aspects of climate change related to atmospheric circulation, which are highly uncertain. Yet, atmospheric circulation strongly mediates climate impacts at the regional scale. In this way, the confidence framework, which focuses on avoiding type 1 errors (false alarms), raises the prospect of committing type 2 errors (missed warnings). This has ethical implications. At the regional scale, however, where information on climate change has to be combined with many other factors affecting vulnerability and exposure—most of which are highly uncertain—the societally relevant question is not ‘What will happen?’ but rather ‘What is the impact of particular actions under an uncertain regional climate change?’ This reframing of the question can cut the Gordian knot of regional climate change information, provided one distinguishes between epistemic and aleatoric uncertainties—something that is generally not done in climate projections. It is argued that the storyline approach to climate change—the identification of physically self-consistent, plausible pathways—has the potential to accomplish precisely this.

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Impact of climate change on groundwater point discharge: backflooding of karstic springs (Loiret, France)

Hydrology and Earth System Sciences ◽

10.5194/hess-15-2459-2011 ◽

2011 ◽

Vol 15 (8) ◽

pp. 2459-2470 ◽

Cited By ~ 6

Author(s):

E. Joigneaux ◽

P. Albéric ◽

H. Pauwels ◽

C. Pagé ◽

L. Terray ◽

...

Keyword(s):

Climate Change ◽

Surface Water ◽

Groundwater Quality ◽

Atmospheric Circulation ◽

Large Scale ◽

Weather Type ◽

Future Climate Change ◽

Impact Of Climate Change ◽

The Impact ◽

Large Scale Atmospheric Circulation

Abstract. Under certain hydrological conditions it is possible for spring flow in karst systems to be reversed. When this occurs, the resulting invasion by surface water, i.e. the backflooding, represents a serious threat to groundwater quality because the surface water could well be contaminated. Here we examine the possible impact of future climate change on the occurrences of backflooding in a specific karst system, having first established the occurrence of such events in the selected study area over the past 40 years. It would appear that backflooding has been more frequent since the 1980s, and that it is apparently linked to river flow variability on the pluri-annual scale. The avenue that we adopt here for studying recent and future variations of these events is based on a downscaling algorithm relating large-scale atmospheric circulation to local precipitation spatial patterns. The large-scale atmospheric circulation is viewed as a set of quasi-stationary and recurrent states, called weather types, and its variability as the transition between them. Based on a set of climate model projections, simulated changes in weather-type occurrence for the end of the century suggests that backflooding events can be expected to decrease in 2075–2099. If such is the case, then the potential risk for groundwater quality in the area will be greatly reduced compared to the current situation. Finally, our results also show the potential interest of the weather-type based downscaling approach for examining the impact of climate change on hydrological systems.

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Regional climate change: Precipitation variability in mountainous part of Bulgaria

Journal of the Geographical Institute Jovan Cvijic SASA ◽

10.2298/ijgi0757079n ◽

2007 ◽

pp. 79-86 ◽

Cited By ~ 1

Author(s):

Nina Nikolova

Keyword(s):

Climate Change ◽

Regional Climate ◽

Regional Climate Change ◽

Precipitation Variability

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Constructing paleoclimate networks from annually laminated lake sediments – the VARDA database

10.5194/egusphere-egu2020-9133 ◽

2020 ◽

Author(s):

Arne Ramisch ◽

Alexander Brauser ◽

Mario Dorn ◽

Cecile Blanchet ◽

Brian Brademann ◽

...

Keyword(s):

Climate Change ◽

Lake Sediments ◽

Large Scale ◽

Regional Climate ◽

Regional Climate Change ◽

Volcanic Eruptions ◽

Scale Model ◽

Graph Database ◽

Varve Thickness ◽

Novel Approach

Reconstructing global patterns of past climate change requires large-scale networks of paleoclimatic archives. Generating paleoclimatic networks relies on precise synchronization of individual records with robust age control. The detailed age constrains of continuous varved lake sediments and the good preservation of isochrones from supra-regional extreme events make these records ideal for constructing large scale continental paleoclimatic networks. Yet, a global synthesis of varved lake archives is missing.Here we present the VARved sediments DAtabase 1.0 (VARDA 1.0), the first global data compilation for varve chronologies and associated palaeoclimatic proxy records. VARDA 1.0 uses a connected data model provided by a state-of-the-art graph database, enabling custom generations of synchronized paleoclimatic networks. We report on compilation strategies for the identification of varved lakes and assimilation of high-resolution chronologies. Existing chronologies have been re-assessed and harmonized using a novel approach that infers information on sedimentation rates enclosed in varve thickness records. This information provides detailed information on the priors required for Bayesian age-depth modelling and strongly improves these results. Additionally, a synthesis of tephra layers from volcanic eruptions provides supra-regional isochrones for synchronizing even distant varved lake records. The current version (VARDA 1.0) comprises 261 datasets from 95 varved lake archives, including chronological information from 14C dating and varve thickness measurements, but also palaeoclimatological proxy data. We further explore potential applications of such networks in paleoclimatic studies, such as identifying leads and lags of regional climate change, large-scale model-data comparisons or differentiated proxy responses between archives. The VARDA graph-database and user interface can be accessed online at https://varve.gfz-potsdam.de.

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Precipitation variability in the Meuse basin in relation to atmospheric circulation

Water Science & Technology ◽

10.2166/wst.2005.0096 ◽

2005 ◽

Vol 51 (5) ◽

pp. 5-14 ◽

Cited By ~ 10

Author(s):

M. Tu ◽

P.J.M. de Laat ◽

M.J. Hall ◽

M.J.M. de Wit

Keyword(s):

Statistical Analysis ◽

Atmospheric Circulation ◽

Large Scale ◽

Precipitation Variability ◽

Past Century ◽

The Past ◽

Winter Half ◽

Summer Half ◽

Large Scale Atmospheric Circulation ◽

Precipitation Events

The distribution of precipitation events in the Meuse basin during the past century has been found to reflect the large-scale atmospheric circulation, as characterised by the Grosswetterlagen system. Statistical analysis of the long observation records (1911–2002) for the basin showed that although the annual (November to October) and winter half-year (November to April) frequencies of wet days (≥1 mm/day) were nearly stable, the associated precipitation amounts have significantly increased since 1980. From 1980 onwards, the very wet days (≥10 mm/day) in the winter half-year have become more frequent. No obvious change was identified for the summer half-year (May to October) very wet days. Both the precipitation amounts of wet and very wet days in the winter half-year and the occurrence of associated atmospheric circulation of the types/sub-types west cyclone, southwest cyclone and northwest cyclone showed a significant increase around 1980.

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Projections of northern hemisphere extratropical climate underestimate internal variability and associated uncertainty

Communications Earth & Environment ◽

10.1038/s43247-021-00268-7 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Christopher H. O’Reilly ◽

Daniel J. Befort ◽

Antje Weisheimer ◽

Tim Woollings ◽

Andrew Ballinger ◽

...

Keyword(s):

Climate Variability ◽

Atmospheric Circulation ◽

Large Scale ◽

Climate Models ◽

Regional Climate ◽

Coupled Model ◽

Internal Variability ◽

Uncertainty Range ◽

Coupled Climate Models ◽

Large Scale Atmospheric Circulation

AbstractInternal climate variability will play a major role in determining change on regional scales under global warming. In the extratropics, large-scale atmospheric circulation is responsible for much of observed regional climate variability, from seasonal to multidecadal timescales. However, the extratropical circulation variability on multidecadal timescales is systematically weaker in coupled climate models. Here we show that projections of future extratropical climate from coupled model simulations significantly underestimate the projected uncertainty range originating from large-scale atmospheric circulation variability. Using observational datasets and large ensembles of coupled climate models, we produce synthetic ensemble projections constrained to have variability consistent with the large-scale atmospheric circulation in observations. Compared to the raw model projections, the synthetic observationally-constrained projections exhibit an increased uncertainty in projected 21st century temperature and precipitation changes across much of the Northern extratropics. This increased uncertainty is also associated with an increase of the projected occurrence of future extreme seasons.

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Regional Climate Impacts of Future Changes in the Mid–Latitude Atmospheric Circulation: a Storyline View

Current Climate Change Reports ◽

10.1007/s40641-019-00146-7 ◽

2019 ◽

Vol 5 (4) ◽

pp. 358-371 ◽

Cited By ~ 8

Author(s):

Giuseppe Zappa

Keyword(s):

Climate Change ◽

Atmospheric Circulation ◽

Regional Climate ◽

Regional Climate Change ◽

Cold Season ◽

Climate Impacts ◽

Surface Warming ◽

Circulation Change ◽

Mean Circulation ◽

Strong Control

Abstract Purpose of Review Atmospheric circulation exerts a strong control on regional climate and extremes. However, projections of future circulation change remain uncertain, thus affecting the assessment of regional climate change. The purpose of this review is to describe some key cases where regional precipitation and windiness strongly depend on the mid-latitude atmospheric circulation response to warming, and summarise this into alternative plausible storylines of regional climate change. Recent Findings Recent research has enabled to better quantify the importance of dynamical aspects of climate change in shaping regional climate. The cold season precipitation response in Mediterranean-like regions is identified as one of the most susceptible impact-relevant aspects of regional climate driven by mid-latitude circulation changes. A circulation-forced drying might already be emerging in the actual Mediterranean, Chile and southwestern Australia. Increasing evidence indicates that distinct regional changes in atmospheric circulation and European windiness might unfold depending on the interplay of different climate drivers, such as surface warming patterns, sea ice loss and stratospheric changes. Summary The multi-model mean circulation response to warming tends to show washed-out signals due to the lack of robustness in the model projections, with implications for regional changes. To better communicate the information contained within these projections, it is useful to discuss regional climate change conditionally on alternative plausible storylines of atmospheric circulation change. As progress continues in understanding the factors driving the response of circulation to global warming, developing such storylines will provide end–to–end and physically self-consistent descriptions of plausible future unfoldings of regional climate change.

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Atmospheric Dynamics is the Largest Source of Uncertainty in Future Winter European Rainfall

Journal of Climate ◽

10.1175/jcli-d-17-0048.1 ◽

2018 ◽

Vol 31 (3) ◽

pp. 963-977 ◽

Cited By ~ 20

Author(s):

David Fereday ◽

Robin Chadwick ◽

Jeff Knight ◽

Adam A. Scaife

Keyword(s):

Atmospheric Circulation ◽

Regional Climate ◽

Regional Climate Change ◽

Precipitation Variability ◽

Atmospheric Dynamics ◽

Substantial Part ◽

Projection Data ◽

Monthly Precipitation ◽

Precipitation Changes ◽

Precipitation Trends

Abstract The IPCC Fifth Assessment Report highlighted large uncertainty in European precipitation changes in the coming century. This paper investigates the sources of intermodel differences using CMIP5 model European precipitation data. The contribution of atmospheric circulation to differences in precipitation trends is investigated by applying cluster analysis to daily mean sea level pressure (MSLP) data. The resulting classification is used to reconstruct monthly precipitation time series, thereby isolating the component of precipitation variability directly related to atmospheric circulation. Reconstructed observed precipitation and reconstructions of simulated historical and projection data are well correlated with the original precipitation series, showing that circulation variability accounts for a substantial fraction of European precipitation variability. Removing the reconstructed precipitation from the original precipitation leaves a residual component related to noncirculation effects (and any small remaining circulation effects). Intermodel spread in residual future European precipitation trends is substantially reduced compared to the spread of the original precipitation trends. Uncertainty in future atmospheric circulation accounts for more than half of the intermodel variance in twenty-first-century precipitation trends for winter months for both northern and southern Europe. Furthermore, a substantial part of this variance is related to different forced dynamical responses in different models and is therefore potentially reducible. These results highlight the importance of understanding future changes in atmospheric dynamics in achieving more robust projections of regional climate change. Finally, the possible dynamical mechanisms that may drive the future differences in regional circulation and precipitation are illustrated by examining simulated teleconnections with tropical precipitation.

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