Articles | Volume 12, issue 1
Research article 04 Feb 2021
Research article | 04 Feb 2021
A new view of heat wave dynamics and predictability over the eastern Mediterranean
Assaf Hochman et al.
Assaf Hochman, Francesco Marra, Gabriele Messori, Joaquim G. Pinto, Shira Raveh-Rubin, Yizhak Yosef, and Georgios Zittis
Earth Syst. Dynam. Discuss.,
Preprint under review for ESDShort summary
Gaining a complete understanding of extreme weather, from its physical drivers to its impacts on society, is important in supporting future risk reduction and adaptation measures. Here, we provide a review of the available scientific literature, knowledge gaps and key open questions in the study of extreme weather events over the vulnerable eastern Mediterranean region.
Julian Francesco Quinting and Christian M. Grams
Geosci. Model Dev. Discuss.,
Preprint under review for GMDShort summary
Physical processes in weather systems importantly affect the midlatitude large-scale circulation. This study introduces an artificial intelligence-based framework which allows the identification of an important weather system – the so-called warm conveyor belt – at comparably low computational costs and from data at low spatial and temporal resolution. The framework thus newly enables the systematic investigation of WCBs in large data sets such as climate model projections.
Assaf Hochman, Francesco Marra, Gabriele Messori, Joaquim G. Pinto, Shira Raveh-Rubin, Yizhak Yosef, and Georgios Zittis
Earth Syst. Dynam. Discuss.,
Preprint under review for ESDShort summary
Gaining a complete understanding of extreme weather, from its physical drivers to its impacts on society, is important in supporting future risk reduction and adaptation measures. Here, we provide a review of the available scientific literature, knowledge gaps and key open questions in the study of extreme weather events over the vulnerable eastern Mediterranean region.
Lisa-Ann Kautz, Olivia Martius, Stephan Pfahl, Joaquim G. Pinto, Alexandre M. Ramos, Pedro M. Sousa, and Tim Woollings
Weather Clim. Dynam. Discuss.,
Preprint under review for WCDShort summary
Atmospheric blocking is associated with stationary, self-sustaining, long-living high pressure systems. They can cause or at least influence surface weather extremes, such as heat waves, cold spells, heavy precipitation events, droughts, or wind extremes. The location of the blocking determines where and what type of extreme event will occur. These relationships are also important for weather prediction and may change due to global warming.
Florian Ehmele, Lisa-Ann Kautz, Hendrik Feldmann, Yi He, Martin Kadlec, Fanni Dora Kelemen, Hilke Simone Lentink, Patrick Ludwig, Desmond Manful, and Joaquim Ginete Pinto
Nat. Hazards Earth Syst. Sci. Discuss.,
Preprint under review for NHESSShort summary
For various applications, it is crucial to have profound knowledge of the frequency, severity, and risk of extreme flood events. Such events are characterized by very long return periods which observations can not cover. We use a large ensemble of regional climate model simulations as input for a hydrological model. Precipitation data were post-processed to reduce systematic errors. The representation of precipitation and discharge is improved and estimates of long return periods become robust.
Kim H. Albers, Patrick Ludwig, Pascal Bertran, Pierre Antoine, Xiaoxu Shi, Gerrit Lohmann, and Joaquim G. Pinto
Clim. Past Discuss.,
Revised manuscript under review for CPShort summary
We use regional climate simulations for the Last Glacial Maximum to reconstruct permafrost and to identify areas of thermal contraction cracking of the ground in western Europe. We find ground cracking, a precondition for the development of permafrost proxies, also south of the probable permafrost border, implying that permafrost was not the limiting factor for proxy development. A good agreement with permafrost and climate proxy data is achieved when easterly winds are modelled more frequently.
Francesco S. R. Pausata, Gabriele Messori, Jayoung Yun, Chetankumar A. Jalihal, Massimo A. Bollasina, and Thomas M. Marchitto
Clim. Past, 17, 1243–1271,Short summary
Far-afield changes in vegetation such as those that occurred over the Sahara during the middle Holocene and the consequent changes in dust emissions can affect the intensity of the South Asian Monsoon (SAM) rainfall and the lengthening of the monsoon season. This remote influence is mediated by anomalies in Indian Ocean sea surface temperatures and may have shaped the evolution of the SAM during the termination of the African Humid Period.
Sebastian Scher and Stefanie Peßenteiner
Hydrol. Earth Syst. Sci., 25, 3207–3225,Short summary
In hydrology, it is often necessary to infer from a daily sum of precipitation a possible distribution over the day – for example how much it rained in each hour. In principle, for a given daily sum, there are endless possibilities. However, some are more likely than others. We show that a method from artificial intelligence called generative adversarial networks (GANs) can
learnwhat a typical distribution over the day looks like.
Gabriele Messori and Davide Faranda
Clim. Past, 17, 545–563,Short summary
The palaeoclimate community must both analyse large amounts of model data and compare very different climates. Here, we present a seemingly very abstract analysis approach that may be fruitfully applied to palaeoclimate numerical simulations. This approach characterises the dynamics of a given climate through a small number of metrics and is thus suited to face the above challenges.
Gabriele Messori, Nili Harnik, Erica Madonna, Orli Lachmy, and Davide Faranda
Earth Syst. Dynam., 12, 233–251,Short summary
Atmospheric jets are a key component of the climate system and of our everyday lives. Indeed, they affect human activities by influencing the weather in many mid-latitude regions. However, we still lack a complete understanding of their dynamical properties. In this study, we try to relate the understanding gained in idealized computer simulations of the jets to our knowledge from observations of the real atmosphere.
Paolo De Luca, Gabriele Messori, Davide Faranda, Philip J. Ward, and Dim Coumou
Earth Syst. Dynam., 11, 793–805,Short summary
In this paper we quantify Mediterranean compound temperature and precipitation dynamical extremes (CDEs) over the 1979–2018 period. The strength of the temperature–precipitation coupling during summer increased and is driven by surface warming. We also link the CDEs to compound hot–dry and cold–wet events during summer and winter respectively.
Susanna Mohr, Jannik Wilhelm, Jan Wandel, Michael Kunz, Raphael Portmann, Heinz Jürgen Punge, Manuel Schmidberger, Julian F. Quinting, and Christian M. Grams
Weather Clim. Dynam., 1, 325–348,Short summary
We investigated an exceptional thunderstorm episode in 2018, in which atmospheric blocking provided large-scale environmental conditions favouring convection. Furthermore, blocking was accompanied by a high cut-off frequency on its upstream side, which together with filaments of high PV provided the mesoscale setting for deep moist convection. The exceptional persistence of low stability combined with weak wind speed in the mid-troposphere over more than 3 weeks has never been observed before.
Florian Ehmele, Lisa-Ann Kautz, Hendrik Feldmann, and Joaquim G. Pinto
Earth Syst. Dynam., 11, 469–490,Short summary
This study presents a large novel data set of climate model simulations for central Europe covering the years 1900–2028 at a 25 km resolution. The focus is on intensive areal precipitation values. The data set is validated against observations using different statistical approaches. The results reveal an adequate quality in a statistical sense as well as some long-term variability with phases of increased and decreased heavy precipitation. The predictions of the near future show continuity.
Christoph P. Gatzen, Andreas H. Fink, David M. Schultz, and Joaquim G. Pinto
Nat. Hazards Earth Syst. Sci., 20, 1335–1351,Short summary
Derechos are widespread, convectively induced severe wind events. A climatology of derechos in Germany is presented. It shows that derechos are not uncommon across the country. Two seasonal peaks indicate a comparable derecho risk in summer and winter. At the same time, we found two different derecho types, a warm- and a cold-season type. We present characteristics of both derecho types that can help forecasters to estimate the potential derecho threat in a given weather situation.
Joaquim G. Pinto and Patrick Ludwig
Clim. Past, 16, 611–626,Short summary
The statistics and characteristics of cyclones over the North Atlantic and Europe are analysed for Last Glacial Maximum (LGM) climate conditions. LGM extreme cyclones were more frequent and characterised by less precipitation and stronger wind speeds than pre-industrial analogues. These results agree with the view of a colder and drier Europe during LGM, with little vegetation and affected by frequent dust storms, leading to the buildup of thick loess deposits in Europe.
Hendrik Andersen, Jan Cermak, Julia Fuchs, Peter Knippertz, Marco Gaetani, Julian Quinting, Sebastian Sippel, and Roland Vogt
Atmos. Chem. Phys., 20, 3415–3438,Short summary
Fog and low clouds (FLCs) are an essential but poorly understood element of Namib regional climate. Here, a satellite-based data set of FLCs in central Namib, reanalysis data, and back trajectories are used to systematically analyze conditions when FLCs occur. Synoptic-scale mechanisms are identified that influence the formation of FLCs and the onshore advection of marine boundary-layer air masses. The findings lead to a new conceptual model of mechanisms that drive FLC variability in the Namib.
Paolo De Luca, Gabriele Messori, Robert L. Wilby, Maurizio Mazzoleni, and Giuliano Di Baldassarre
Earth Syst. Dynam., 11, 251–266,Short summary
We show that floods and droughts can co-occur in time across remote regions on the globe and introduce metrics that can help in quantifying concurrent wet and dry hydrological extremes. We then link wet–dry extremes to major modes of climate variability (i.e. ENSO, PDO, and AMO) and provide their spatial patterns. Such concurrent extreme hydrological events may pose risks to regional hydropower production and agricultural yields.
Karmen Babić, Norbert Kalthoff, Bianca Adler, Julian F. Quinting, Fabienne Lohou, Cheikh Dione, and Marie Lothon
Atmos. Chem. Phys., 19, 13489–13506,Short summary
This study investigates differences in atmospheric conditions between nights with and without low-level stratus clouds (LLCs) over southern West Africa. We use high-quality observations collected during 2016 summer monsoon season and the ERA5 reanalysis data set. Our results show that the formation of LLCs depends on the interplay between the onset time and strength of the nocturnal low-level jet, horizontal cold-air advection, and the overall moisture level in the whole region.
Sebastian Scher and Gabriele Messori
Nonlin. Processes Geophys., 26, 381–399,Short summary
Neural networks are a technique that is widely used to predict the time evolution of physical systems. For this the past evolution of the system is shown to the neural network – it is
trained– and then can be used to predict the evolution in the future. We show some limitations in this approach for certain systems that are important to consider when using neural networks for climate- and weather-related applications.
Davide Faranda, Yuzuru Sato, Gabriele Messori, Nicholas R. Moloney, and Pascal Yiou
Earth Syst. Dynam., 10, 555–567,Short summary
We show how the complex dynamics of the jet stream at midlatitude can be described by a simple mathematical model. We match the properties of the model to those obtained by the jet data derived from observations.
Sebastian Scher and Gabriele Messori
Geosci. Model Dev., 12, 2797–2809,Short summary
Currently, weather forecasts are mainly produced by using computer models based on physical equations. It is an appealing idea to use neural networks and “deep learning” for weather forecasting instead. We successfully test the possibility of using deep learning for weather forecasting by considering climate models as simplified versions of reality. Our work therefore is a step towards potentially using deep learning to replace or accompany current weather forecasting models.
Luca Mathias, Patrick Ludwig, and Joaquim G. Pinto
Nat. Hazards Earth Syst. Sci., 19, 1023–1040,Short summary
Convective systems producing severe winds occasionally affect Europe during wintertime and the majority of these storms develop along well-defined cold fronts of extratropical cyclones. However, on 3 January 2014, a storm formed in a postfrontal air mass over western Europe. This study analyses the prevailing environmental conditions and the predictability of this storm. Our results reveal the difficulty of forecasting cold-season convective storms when they are not associated with a cold front.
Mark Reyers, Hendrik Feldmann, Sebastian Mieruch, Joaquim G. Pinto, Marianne Uhlig, Bodo Ahrens, Barbara Früh, Kameswarrao Modali, Natalie Laube, Julia Moemken, Wolfgang Müller, Gerd Schädler, and Christoph Kottmeier
Earth Syst. Dynam., 10, 171–187,Short summary
In this study, the regional MiKlip decadal prediction system is evaluated. This system has been established to deliver highly resolved forecasts for the timescale of 1 to 10 years for Europe. Evidence of the general potential for regional decadal predictability for the variables temperature, precipitation, and wind speed is provided, but the performance of the prediction system depends on region, variable, and system generation.
Lisa-Ann Kautz, Florian Ehmele, Patrick Ludwig, Hilke S. Lentink, Fanni D. Kelemen, Martin Kadlec, and Joaquim G. Pinto
Hydrol. Earth Syst. Sci. Discuss.,
Manuscript not accepted for further reviewShort summary
To quantify the flooding risk for Europe it is necessary to run hydrological models. As input for these models, a consistent stochastic precipitation dataset is needed. In the present study, a combined approach is presented on how to generate such a dataset based on dynamical downscaling and subsequent bias correction. Empirical quantile mapping was identified as suitable bias correction method as it led to improvements for specific severe river floods as well as in a climatological perspective.
Matthew D. K. Priestley, Helen F. Dacre, Len C. Shaffrey, Kevin I. Hodges, and Joaquim G. Pinto
Nat. Hazards Earth Syst. Sci., 18, 2991–3006,Short summary
This study investigates the role of the clustering of extratropical cyclones in driving wintertime wind losses across a large European region. To do this over 900 years of climate model data have been used and analysed. The main conclusion of this work is that cyclone clustering acts to increase wind-driven losses in the winter by 10 %–20 % when compared to the losses from a random series of cyclones, with this specifically being for the higher loss years.
Jorge Eiras-Barca, Alexandre M. Ramos, Joaquim G. Pinto, Ricardo M. Trigo, Margarida L. R. Liberato, and Gonzalo Miguez-Macho
Earth Syst. Dynam., 9, 91–102,Short summary
This paper analyses the potential role of atmospheric rivers in the explosive cyclone deepening. Using ERA-Interim reanalysis data for 1979–2011, we analyse the concurrence of atmospheric rivers and explosive cyclogenesis over the North Atlantic and North Pacific basins for the extended winter months (ONDJFM).
Davide Faranda, Gabriele Messori, M. Carmen Alvarez-Castro, and Pascal Yiou
Nonlin. Processes Geophys., 24, 713–725,Short summary
We study the dynamical properties of the Northern Hemisphere atmospheric circulation by analysing the sea-level pressure, 2 m temperature, and precipitation frequency field over the period 1948–2013. The metrics are linked to the predictability and the persistence of the atmospheric flows. We study the dependence on the seasonal cycle and the fields corresponding to maxima and minima of the dynamical indicators.
F. S. R. Pausata, M. Gaetani, G. Messori, S. Kloster, and F. J. Dentener
Atmos. Chem. Phys., 15, 1725–1743,Short summary
our study suggests that future aerosol abatement may be the primary driver of increased blocking events over the western Mediterranean. This modification of the atmospheric circulation over the Euro-Atlantic sector leads to more stagnant weather conditions that favour air pollutant accumulation especially in the western Mediterranean sector. Changes in atmospheric circulation should therefore be included in future air pollution mitigation assessments.
M. K. Karremann, J. G. Pinto, P. J. von Bomhard, and M. Klawa
Nat. Hazards Earth Syst. Sci., 14, 2041–2052,
M. L. R. Liberato, J. G. Pinto, R. M. Trigo, P. Ludwig, P. Ordóñez, D. Yuen, and I. F. Trigo
Nat. Hazards Earth Syst. Sci., 13, 2239–2251,
Related subject area
Earth system change: climate predictionAbrupt climate change as a rate-dependent cascading tipping pointBayesian estimation of Earth's climate sensitivity and transient climate response from observational warming and heat content datasetsComparison of CMIP6 historical climate simulations and future projected warming to an empirical model of global climateAssessment of a full-field initialized decadal climate prediction system with the CMIP6 version of EC-EarthEmergent constraints on equilibrium climate sensitivity in CMIP5: do they hold for CMIP6?Dating hiatuses: a statistical model of the recent slowdown in global warming and the next oneCalibrating large-ensemble European climate projections using observational dataReduced global warming from CMIP6 projections when weighting models by performance and independenceEmergent constraints on transient climate response (TCR) and equilibrium climate sensitivity (ECS) from historical warming in CMIP5 and CMIP6 modelsMultivariate bias corrections of climate simulations: which benefits for which losses?Historical and future anthropogenic warming effects on droughts, fires and fire emissions of CO2 and PM2.5 in equatorial Asia when 2015-like El Niño events occurThe impact of regional climate model formulation and resolution on simulated precipitation in AfricaBayesian deconstruction of climate sensitivity estimates using simple models: implicit priors and the confusion of the inverseIntensification of the hydrological cycle expected in West Africa over the 21st centuryWinter hydrometeorological extreme events modulated by large-scale atmospheric circulation in southern OntarioInvestigating ENSO and its teleconnections under climate change in an ensemble view – a new perspectiveHuman influence on European winter wind storms such as those of January 2018September Arctic sea ice minimum prediction – a skillful new statistical approachESD Reviews: Model dependence in multi-model climate ensembles: weighting, sub-selection and out-of-sample testingPredicting near-term variability in ocean carbon uptakeA mathematical approach to understanding emergent constraintsSeasonal prediction skill of East Asian summer monsoon in CMIP5 modelsAssessing the impact of a future volcanic eruption on decadal predictionsProjections of East Asian summer monsoon change at global warming of 1.5 and 2 °CChanges in extremely hot days under stabilized 1.5 and 2.0 °C global warming scenarios as simulated by the HAPPI multi-model ensembleRegional scaling of annual mean precipitation and water availability with global temperature changeIrreversible ocean thermal expansion under carbon dioxide removalChanges in tropical cyclones under stabilized 1.5 and 2.0 °C global warming scenarios as simulated by the Community Atmospheric Model under the HAPPI protocolsSelecting a climate model subset to optimise key ensemble propertiesReturn levels of temperature extremes in southern PakistanOn the meaning of independence in climate scienceMinimal change of thermal continentality in Slovakia within the period 1961–2013Lifetime of soil moisture perturbations in a coupled land–atmosphere simulationThe ScaLIng Macroweather Model (SLIMM): using scaling to forecast global-scale macroweather from months to decadesIce supersaturation and the potential for contrail formation in a changing climateGlobal hydrological droughts in the 21st century under a changing hydrological regimeProjecting Antarctic ice discharge using response functions from SeaRISE ice-sheet modelsDo GCMs predict the climate ... or macroweather?A trend-preserving bias correction – the ISI-MIP approachScenario and modelling uncertainty in global mean temperature change derived from emission-driven global climate modelsA scaling approach to project regional sea level rise and its uncertaintiesOn the determination of the global cloud feedback from satellite measurements
Johannes Lohmann, Daniele Castellana, Peter D. Ditlevsen, and Henk A. Dijkstra
Earth Syst. Dynam., 12, 819–835,Short summary
Tipping of one climate subsystem could trigger a cascade of subsequent tipping points and even global-scale climate tipping. Sequential shifts of atmosphere, sea ice and ocean have been recorded in proxy archives of past climate change. Based on this we propose a conceptual model for abrupt climate changes of the last glacial. Here, rate-induced tipping enables tipping cascades in systems with relatively weak coupling. An early warning signal is proposed that may detect such a tipping.
Philip Goodwin and B. B. Cael
Earth Syst. Dynam., 12, 709–723,Short summary
Climate sensitivityis a key measure of how sensitive Earth's climate is to human release of greenhouse gasses, such as from fossil fuels. However, there is still uncertainty as to the value of climate sensitivity, in part because different climate feedbacks operate over multiple timescales. This study assesses hundreds of millions of climate simulations against historical observations to reduce uncertainty in climate sensitivity and future climate warming.
Laura A. McBride, Austin P. Hope, Timothy P. Canty, Brian F. Bennett, Walter R. Tribett, and Ross J. Salawitch
Earth Syst. Dynam., 12, 545–579,Short summary
We use a reduced-complexity climate model trained by observations to show that at the current rate of human release of CO2, total cumulative emissions will pass the 66 % likelihood of limiting warming to 1.5° or 2°C in about 10 and 35 years, respectively. We also show that complex climate models often used to guide policy tend to warm faster than observed over the past few decades. To achieve the Paris Climate Agreement, CO2 and CH4 emissions must be severely curtailed in the next decade.
Roberto Bilbao, Simon Wild, Pablo Ortega, Juan Acosta-Navarro, Thomas Arsouze, Pierre-Antoine Bretonnière, Louis-Philippe Caron, Miguel Castrillo, Rubén Cruz-García, Ivana Cvijanovic, Francisco Javier Doblas-Reyes, Markus Donat, Emanuel Dutra, Pablo Echevarría, An-Chi Ho, Saskia Loosveldt-Tomas, Eduardo Moreno-Chamarro, Núria Pérez-Zanon, Arthur Ramos, Yohan Ruprich-Robert, Valentina Sicardi, Etienne Tourigny, and Javier Vegas-Regidor
Earth Syst. Dynam., 12, 173–196,Short summary
This paper presents and evaluates a set of retrospective decadal predictions with the EC-Earth3 climate model. These experiments successfully predict past changes in surface air temperature but show poor predictive capacity in the subpolar North Atlantic, a well-known source region of decadal climate variability. The poor predictive capacity is linked to an initial shock affecting the Atlantic Ocean circulation, ultimately due to a suboptimal representation of the Labrador Sea density.
Manuel Schlund, Axel Lauer, Pierre Gentine, Steven C. Sherwood, and Veronika Eyring
Earth Syst. Dynam., 11, 1233–1258,Short summary
As an important measure of climate change, the Equilibrium Climate Sensitivity (ECS) describes the change in surface temperature after a doubling of the atmospheric CO2 concentration. Climate models from the Coupled Model Intercomparison Project (CMIP) show a wide range in ECS. Emergent constraints are a technique to reduce uncertainties in ECS with observational data. Emergent constraints developed with data from CMIP phase 5 show reduced skill and higher ECS ranges when applied to CMIP6 data.
J. Isaac Miller and Kyungsik Nam
Earth Syst. Dynam., 11, 1123–1132,Short summary
We augment an energy balance model with a novel measure of the oceans' multidecadal temperatures cycles to assess the contributions of model forcings and natural variability to the so-called hiatus in global warming. The model partially explains the recent slowdown and explains nearly all of the subsequent warming. The natural cycle suggests the possibility of a much longer hiatus over roughly 2023–2061.
Christopher H. O'Reilly, Daniel J. Befort, and Antje Weisheimer
Earth Syst. Dynam., 11, 1033–1049,Short summary
This study examines how the output of large single-model ensembles can be calibrated using observational data to provide improved future projections over Europe. Using an out-of-sample
imperfect modeltest, in which calibration techniques are applied to individual climate model realisations, these techniques are shown to generally improve the reliability of European climate projections for the next 40 years, particularly for regional surface temperature.
Lukas Brunner, Angeline G. Pendergrass, Flavio Lehner, Anna L. Merrifield, Ruth Lorenz, and Reto Knutti
Earth Syst. Dynam., 11, 995–1012,Short summary
In this study, we weight climate models by their performance with respect to simulating aspects of historical climate and their degree of interdependence. Our method is found to increase projection skill and to correct for structurally similar models. The weighted end-of-century mean warming (2081–2100 relative to 1995–2014) is 3.7 °C with a likely (66 %) range of 3.1 to 4.6 °C for the strong climate change scenario SSP5-8.5; this is a reduction of 0.4 °C compared with the unweighted mean.
Femke J. M. M. Nijsse, Peter M. Cox, and Mark S. Williamson
Earth Syst. Dynam., 11, 737–750,Short summary
One of the key questions in climate science is how much more heating we will get for a given rise in carbon dioxide in the atmosphere. A new generation of models showed that this might be more than previously expected. Comparing the new models to observed temperature rise since 1970, we show that there is no need to revise the estimate upwards. Air pollution, whose effect on climate warming is poorly understood, stopped rising, allowing us to better constrain the greenhouse gas signal.
Bastien François, Mathieu Vrac, Alex J. Cannon, Yoann Robin, and Denis Allard
Earth Syst. Dynam., 11, 537–562,Short summary
Recently, multivariate bias correction (MBC) methods designed to adjust climate simulations have been proposed. However, they use different approaches, leading potentially to different results. Therefore, this study intends to intercompare four existing MBC methods to provide end users with aid in choosing such methods for their applications. To do so, a wide range of evaluation criteria have been used to assess the ability of MBC methods to correct statistical properties of climate models.
Hideo Shiogama, Ryuichi Hirata, Tomoko Hasegawa, Shinichiro Fujimori, Noriko N. Ishizaki, Satoru Chatani, Masahiro Watanabe, Daniel Mitchell, and Y. T. Eunice Lo
Earth Syst. Dynam., 11, 435–445,Short summary
Based on climate simulations, we suggested that historical warming increased chances of drought exceeding the severe 2015 event in equatorial Asia due to El Niño. The fire and fire emissions of CO2/PM2.5 will largely increase at 1.5 and 2 °C warming. If global warming reaches 3 °C, as is expected from the current mitigation policies, chances of fire and CO2/PM2.5 emissions exceeding the 2015 event become approximately 100 %. Future climate policy has to consider these climate change effects.
Minchao Wu, Grigory Nikulin, Erik Kjellström, Danijel Belušić, Colin Jones, and David Lindstedt
Earth Syst. Dynam., 11, 377–394,Short summary
Regional Climate Models constitute a downscaling tool to provide high-resolution data for impact and adaptation studies. However, there is no unique definition of the added value of downscaling as it depends on many factors. We investigate the impact of spatial resolution and model formulation on downscaled rainfall in Africa. Our results show that improvements in downscaled rainfall compared to the driving reanalysis are often related to model formulation and not always to higher resolution.
James D. Annan and Julia C. Hargreaves
Earth Syst. Dynam., 11, 347–356,Short summary
We explore the implicit assumptions that underlie many published probabilistic estimates of the equilibrium climate sensitivity – that is, the amount the climate will warm under a doubling of the atmospheric CO2 concentration. We demonstrate that many such estimates have made assumptions that would be difficult to justify and show how the calculations can be repeated in a more defensible manner. Our results show some significant differences from previous calculations.
Stella Todzo, Adeline Bichet, and Arona Diedhiou
Earth Syst. Dynam., 11, 319–328,Short summary
This study uses climate projections over West Africa to investigate the future changes in different aspects of its hydrological cycle. Over the 21st century, temperatures are expected to increase at a faster rate (+0.5 °C per decade) than the global average (+0.3 °C per decade), leading to an intensification of the hydrological cycle on average of +11 % per °C over the Sahel (more intense precipitation and longer dry spells) and +3 % per °C over the Guinea Coast (more intense precipitation).
Olivier Champagne, Martin Leduc, Paulin Coulibaly, and M. Altaf Arain
Earth Syst. Dynam., 11, 301–318,Short summary
Southern Ontario has seen more high flows in winter recently due to earlier snowmelt. We show that 10 mm of daily rain and temperature higher than 5 °C are necessary conditions to generate winter high flows in the historical period. These conditions are associated with high pressure on the east coast bringing warm and wet conditions from the south. In the future, as snowfall decreases, warm events will generate less high flows, while rainfall will become a greater high-flow contributor.
Tímea Haszpra, Mátyás Herein, and Tamás Bódai
Earth Syst. Dynam., 11, 267–280,Short summary
We investigate the changes in the ENSO phenomenon and the alterations of its precipitation-related teleconnections in the CESM-LE. To avoid the disadvantages of the subjective choices of traditional temporal methods, we use an ensemble-based snapshot framework providing instantaneous quantities computed over the ensemble dimension of the simulation. We find that ENSO teleconnections undergo considerable changes, and the ENSO amplitude remarkably increases by 2100.
Robert Vautard, Geert Jan van Oldenborgh, Friederike E. L. Otto, Pascal Yiou, Hylke de Vries, Erik van Meijgaard, Andrew Stepek, Jean-Michel Soubeyroux, Sjoukje Philip, Sarah F. Kew, Cecilia Costella, Roop Singh, and Claudia Tebaldi
Earth Syst. Dynam., 10, 271–286,Short summary
The effect of human activities on the probability of winter wind storms like the ones that occurred in Western Europe in January 2018 is analysed using multiple model ensembles. Despite a significant probability decline in observations, we find no significant change in probabilities due to human influence on climate so far. However, such extreme events are likely to be slightly more frequent in the future. The observed decrease in storminess is likely to be due to increasing roughness.
Monica Ionita, Klaus Grosfeld, Patrick Scholz, Renate Treffeisen, and Gerrit Lohmann
Earth Syst. Dynam., 10, 189–203,Short summary
Based on a simple statistical model we show that the September sea ice extent has a high predictive skill, up to 4 months ahead, based on previous months' oceanic and atmospheric conditions. Our statistical model skillfully captures the interannual variability of the September sea ice extent and could provide a valuable tool for identifying relevant regions and oceanic and atmospheric parameters that are important for the sea ice development in the Arctic.
Gab Abramowitz, Nadja Herger, Ethan Gutmann, Dorit Hammerling, Reto Knutti, Martin Leduc, Ruth Lorenz, Robert Pincus, and Gavin A. Schmidt
Earth Syst. Dynam., 10, 91–105,Short summary
Best estimates of future climate projections typically rely on a range of climate models from different international research institutions. However, it is unclear how independent these different estimates are, and, for example, the degree to which their agreement implies robustness. This work presents a review of the varied and disparate attempts to quantify and address model dependence within multi-model climate projection ensembles.
Nicole S. Lovenduski, Stephen G. Yeager, Keith Lindsay, and Matthew C. Long
Earth Syst. Dynam., 10, 45–57,Short summary
This paper shows that the absorption of carbon dioxide by the ocean is predictable several years in advance. This is important because fossil-fuel-derived carbon dioxide is largely responsible for anthropogenic global warming and because carbon dioxide emission management and global carbon cycle budgeting exercises can benefit from foreknowledge of ocean carbon absorption. The promising results from this new forecast system justify the need for additional oceanic observations.
Femke J. M. M. Nijsse and Henk A. Dijkstra
Earth Syst. Dynam., 9, 999–1012,Short summary
State-of-the-art climate models sometimes differ in their prediction of key aspects of climate change. The technique of
emergent constraintsuses observations of current climate to improve those predictions, using relationships between different climate models. Our paper first classifies the different uses of the technique, and continues with proposing a mathematical justification for their use. We also highlight when the application of emergent constraints might give biased predictions.
Bo Huang, Ulrich Cubasch, and Christopher Kadow
Earth Syst. Dynam., 9, 985–997,Short summary
We find that CMIP5 models show more significant improvement in predicting zonal winds with initialisation than without initialisation based on the knowledge that zonal wind indices can be used as potential predictors for the EASM. Given the initial conditions, two models improve the seasonal prediction skill of the EASM, while one model decreases it. The models have different responses to initialisation due to their ability to depict the EASM–ESNO coupled mode.
Sebastian Illing, Christopher Kadow, Holger Pohlmann, and Claudia Timmreck
Earth Syst. Dynam., 9, 701–715,
Jiawei Liu, Haiming Xu, and Jiechun Deng
Earth Syst. Dynam., 9, 427–439,Short summary
A novel method based on
present–futurerelationship in observed climate and model-simulated future climate is applied to give more reliable projections of East Asian summer monsoon intensity and associated precipitation changes at 1.5 and 2 °C warming levels. Projected future changes suggest decreased precipitation over the Meiyu belt and increased precipitation over the high latitudes of East Asia and central China, together with a considerable weakening of EASM intensity.
Michael Wehner, Dáithí Stone, Dann Mitchell, Hideo Shiogama, Erich Fischer, Lise S. Graff, Viatcheslav V. Kharin, Ludwig Lierhammer, Benjamin Sanderson, and Harinarayan Krishnan
Earth Syst. Dynam., 9, 299–311,Short summary
The United Nations Framework Convention on Climate Change challenged the scientific community to describe the impacts of stabilizing the global temperature at its 21st Conference of Parties. A specific target of 1.5 °C above preindustrial levels had not been seriously considered by the climate modeling community prior to the Paris Agreement. This paper analyzes heat waves in simulations designed for this target. We find there are reductions in extreme temperature compared to a 2 °C target.
Peter Greve, Lukas Gudmundsson, and Sonia I. Seneviratne
Earth Syst. Dynam., 9, 227–240,Short summary
Assessing projected hydroclimatological changes is crucial, but associated with large uncertainties. We statistically assess here the response of precipitation and water availability to global temperature change, enabling us to estimate the significance of drying/wetting tendencies under anthropogenic climate change. We further show that opting for a 1.5 K warming target just slightly influences the mean response but could substantially reduce the risk of experiencing extreme changes.
Dana Ehlert and Kirsten Zickfeld
Earth Syst. Dynam., 9, 197–210,Short summary
This study uses a global climate model to explore the extent to which sea level rise due to thermal expansion of the ocean is reversible if the atmospheric concentration of carbon dioxide (CO2) declines. It is found that sea level continues to rise for several decades after atmospheric CO2 starts to decline and does not return to the pre-industrial level for over thousand years after atmospheric CO2 is restored to the pre-industrial concentration.
Michael F. Wehner, Kevin A. Reed, Burlen Loring, Dáithí Stone, and Harinarayan Krishnan
Earth Syst. Dynam., 9, 187–195,Short summary
The United Nations Framework Convention on Climate Change invited the scientific community to explore the impacts of a world in which anthropogenic global warming is stabilized at only 1.5 °C above preindustrial average temperatures. We present a projection of future tropical cyclone statistics for both 1.5 and 2.0 °C stabilized warming scenarios using a high-resolution global climate model. We find more frequent and intense tropical cyclones, but a reduction in weaker storms.
Nadja Herger, Gab Abramowitz, Reto Knutti, Oliver Angélil, Karsten Lehmann, and Benjamin M. Sanderson
Earth Syst. Dynam., 9, 135–151,Short summary
Users presented with large multi-model ensembles commonly use the equally weighted model mean as a best estimate, ignoring the issue of near replication of some climate models. We present an efficient and flexible tool that finds a subset of models with improved mean performance compared to the multi-model mean while at the same time maintaining the spread and addressing the problem of model interdependence. Out-of-sample skill and reliability are demonstrated using model-as-truth experiments.
Maida Zahid, Richard Blender, Valerio Lucarini, and Maria Caterina Bramati
Earth Syst. Dynam., 8, 1263–1278,Short summary
The southern part of Pakistan (Sindh province) has been exposed to frequent and intense temperature extremes recently and is highly vulnerable to their impacts due to lack of information on recurrence of extremes. In this paper for the first time we estimated the return levels of daily maximum temperatures and daily maximum wet-bulb temperatures over the different return periods in Sindh, which would help the local administrations to prioritize the regions in terms of adaptations.
James D. Annan and Julia C. Hargreaves
Earth Syst. Dynam., 8, 211–224,Short summary
The concept of independence has been frequently raised in climate science, but has rarely been defined and discussed in a theoretically robust and quantifiable manner. Improved understanding of this topic is critical to better understanding of climate change. In this paper, we introduce a unifying approach based on the statistical definition of independence, and illustrate with simple examples how it can be applied to practical questions.
Jozef Vilček, Jaroslav Škvarenina, Jaroslav Vido, Paulína Nalevanková, Radoslav Kandrík, and Jana Škvareninová
Earth Syst. Dynam., 7, 735–744,Short summary
Thermal continentality plays an important role not only in the basic characterisation of the climate in particular regions but also in the phytogeographic distribution of plants and ecosystem formation. Due to ongoing climate change, questions surrounding the changes of thermal continentality are very relevant. Our results show that the continentality of Slovakia increased in the period 1961 to 2013; however, this trend is not significant.
T. Stacke and S. Hagemann
Earth Syst. Dynam., 7, 1–19,Short summary
This study evaluates the lifetime of soil moisture perturbations using an atmosphere-land GCM. We find memory of up to 9 months for root zone soil moisture. Interactions with other surface states result in significant but short-lived anomalies in surface temperature and more stable anomalies in leaf carbon content. As these anomalies can recur repeatedly, e.g. due to interactions with a deep-soil moisture reservoir, we conclude that soil moisture initialization may impact climate predictions.
S. Lovejoy, L. del Rio Amador, and R. Hébert
Earth Syst. Dynam., 6, 637–658,Short summary
Numerical climate models forecast the weather well beyond the deterministic limit. In this “macroweather” regime, they are random number generators. Stochastic models can have more realistic noises and can be forced to converge to the real-world climate. Existing stochastic models do not exploit the very long atmospheric and oceanic memories. With skill up to decades, our new ScaLIng Macroweather Model (SLIMM) exploits this to make forecasts more accurate than GCMs.
E. A. Irvine and K. P. Shine
Earth Syst. Dynam., 6, 555–568,Short summary
Aviation impacts on climate via contrails, which are often clearly visible in the sky. Contrail formation requires particular cold/moist atmospheric conditions at aircraft cruise altitudes. Climate change is expected to change these conditions. Using simulations from several climate models we conclude that, by 2100, the probability of contrail formation could decrease from 11 to 7%, mostly due to changing conditions in the tropics. There is no consensus on the likely change in mid-latitudes.
N. Wanders, Y. Wada, and H. A. J. Van Lanen
Earth Syst. Dynam., 6, 1–15,Short summary
This study shows the impact of a changing climate on hydrological drought. The study illustrates that an alternative drought identification that considers adaptation to an altered hydrological regime has a substantial influence on the way in which drought impact is calculated. The obtained results show that an adaptive threshold approach is the way forward to study the impact of climate change on the identification and characterization of hydrological drought events.
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Skillful forecasts of extreme weather events have a major socioeconomic relevance. Here, we compare two approaches to diagnose the predictability of eastern Mediterranean heat waves: one based on recent developments in dynamical systems theory and one leveraging numerical ensemble weather forecasts. We conclude that the former can be a useful and cost-efficient complement to conventional numerical forecasts for understanding the dynamics of eastern Mediterranean heat waves.
Skillful forecasts of extreme weather events have a major socioeconomic relevance. Here, we...