High-Resolution Decadal Drought Predictions for German Water Boards: A Case Study for the Wupper Catchment

Water boards in Germany require decadal predictions to develop optimized management and adaptation strategies, especially within the claims of flood protection and water distribution management. Specifically, the Wupper catchment water board in western Germany is interested in decadal predictions of drought indices, which are correlated to dam water levels. For the management of small catchments, they need multi-year means and multi-year seasonal means of the hydrological seasons for forecast years 1–3 at high spatial resolution. Thus, the MPI-ESM-LR global decadal prediction system with 16 ensemble members at 200 km resolution was statistically downscaled with EPISODES to ~11 km in Germany. Simulated precipitation was recalibrated, correcting model errors and adjusting the ensemble spread. We tested different recalibration settings to optimize the skill. The 3-year mean and 3-year seasonal mean SPI (Standardized Precipitation Index), indicating excess or deficit of precipitation, was calculated. We evaluated the prediction skill with HYRAS observations, applying skill scores and correlation coefficients, and tested the significance of the skill at a 95% level via 1,000 bootstraps. We found that the high-resolution statistical downscaling is able to preserve the skill of the global decadal predictions and that the recalibration can clearly improve the precipitation skill in Germany. Multi-year annual and August–October mean SPI predictions are promising for several regions in Germany. Additionally, there is potential for skill improvement with increasing ensemble size for all temporal aggregations, except for November–January. A user-oriented product sheet was developed and published on the Copernicus Climate Change Service website (https://climate.copernicus.eu/decadal-predictions-infrastructure). It provides 3-year mean probabilistic SPI predictions for the Wupper catchment and north-western Germany. For 2021–2023, a high probability of negative SPI (dry conditions) is predicted in most of the area. The decadal prediction skill is higher than using the observed climatology as reference prediction in several parts of the area. This case study was developed in cooperation with the Wupper catchment water board and discussed with further German water managers: The skill of high-resolution decadal drought predictions is considered to be promising to fulfill their needs. The product sheet is understandable, well-structured and can be applied to their working routines

Recent applications and potential of near-term (interannual to decadal) climate predictions

Following efforts from leading centres for climate forecasting, sustained routine operational near-term climate predictions (NTCP) are now produced that bridge the gap between seasonal forecasts and climate change projections offering the prospect of seamless climate services. Though NTCP is a new area of climate science and active research is taking place to increase understanding of the processes and mechanisms required to produce skillful predictions, this significant technical achievement combines advances in initialisation with ensemble prediction of future climate up to a decade ahead. With a growing NTCP database, the predictability of the evolving externally-forced and internally-generated components of the climate system can now be quantified. Decision-makers in key sectors of the economy can now begin to assess the utility of these products for informing climate risk and for planning adaptation and resilience strategies up to a decade into the future. Here, case studies are presented from finance and economics, water management, agriculture and fisheries management demonstrating the emerging utility and potential of operational NTCP to inform strategic planning across a broad range of applications in key sectors of the global economy

Recent applications and potential of near-term (interannual to decadal) climate predictions

Following efforts from leading centres for climate forecasting, sustained routine operational near-term climate predictions (NTCP) are now produced that bridge the gap between seasonal forecasts and climate change projections offering the prospect of seamless climate services. Though NTCP is a new area of climate science and active research is taking place to increase understanding of the processes and mechanisms required to produce skillful predictions, this significant technical achievement combines advances in initialisation with ensemble prediction of future climate up to a decade ahead. With a growing NTCP database, the predictability of the evolving externally-forced and internally-generated components of the climate system can now be quantified. Decision-makers in key sectors of the economy can now begin to assess the utility of these products for informing climate risk and for planning adaptation and resilience strategies up to a decade into the future. Here, case studies are presented from finance and economics, water management, agriculture and fisheries management demonstrating the emerging utility and potential of operational NTCP to inform strategic planning across a broad range of applications in key sectors of the global economy

Aufbau eines globalen Bottom-up-Schiffsemissionskatasters unter Berücksichtigung zukünftiger polarer Schiffsrouten

Zur exakten Erfassung von Schiffsemissionen entwickelt die vorliegende Studie ein globales Bottom-up-Emissionskataster der internationalen Schifffahrt, das einen besseren räumlichen Bezug als globale Top-down-Berechnungen und im Gegensatz zu existierenden regionalen Bottom-up-Ansätzen erstmals eine globale Abdeckung aufweist. Als Eingangsdatensatz dienen individuelle Schiffsbewegungen und -eigenschaften einer Lloyds-Schiffsstatistik von 2006. Der in dieser Studie erarbeitete verbesserte Dijkstra-Algorithmus findet für jede Kombination aus Start- und Zielhäfen einer Schiffsbewegung die kürzeste Route im 1°x1°-Modellgitter unter Berücksichtigung von Land, Meereis und Schifffahrtskanälen und mit Großkreis-Annäherung über offenem Ozean. Zurückweichendes Meereis ermöglicht in zwei Zukunftsszenarien des Jahres 2050 im Gegensatz zu einem gegenwärtigen Basisszenario von 2006 die Öffnung polarer Schiffsrouten. Zur Entwicklung des globalen Bottom-up-Emissionskatasters wird auf allen Gitterboxen jeder Schiffsroute aus der berechneten Distanz und gemittelten Motorangaben der Treibstoffverbrauch und die Emissionen von NOx, CO2, SOx, CO, Hydrocarbonen und Partikeln ermittelt. Die resultierende gegenwärtige Schiffsverteilung stimmt mit Beobachtungsdaten gut überein und der gegenwärtige globale Treibstoffverbrauch von 268 Mt für das Jahr 2006 liegt im Bereich bisheriger globaler Top-down-Berechnungen und regionaler Bottom-up-Ansätze. Die zukünftige Schiffsverteilung zeigt aufgrund der gegenwärtigen Schifffahrts-Logistik in der vorliegenden Lloyds-Schiffsstatik eine geringere Schiffsaktivität auf den Nordpolarrouten als bisherige Abschätzungen. Dennoch zeigt die regionale Schiffsaktivität bzw. der Treibstoffverbrauch auf der Nordost-Passage bis 2050 einen Anstieg um die Faktoren 450-600 bzw. 900-1.500 in den beiden Zukunftsszenarien. Die Nordwest-Passage weist sogar noch höhere Wachstumsfaktoren von 1.600-2.100 bzw. 1.300-2.300 auf. Der errechnete globale Treibstoffverbrauch von 352-626 Mt für das Jahr 2050 ist konsistent mit bisherigen Studien. Dabei zeigt sich auch, dass adäquate Reduktionsmaßnahmen einen zukünftigen Anstieg der Emissionen im Zuge des prognostizierten Weltwirtschaftswachstums verhindern können

Zukünftige Veränderungen von Klimamittelwerten und -extremwerten im Mittelmeerraum abgeleitet von einem regionalen Klimamodell

The Mediterranean area reveals a strong vulnerability to future climate change due to a high exposure to projected impacts and a low capacity for adaptation highlighting the need for robust regional or local climate change projections, especially for extreme events strongly affecting the Mediterranean environment. The prevailing study investigates two major topics of the Mediterranean climate variability: the analysis of dynamical downscaling of present-day and future temperature and precipitation means and extremes from global to regional scale and the comprehensive investigation of temperature and rainfall extremes including the estimation of uncertainties and the comparison of different statistical methods for precipitation extremes. For these investigations, several observational datasets of CRU, E-OBS and original stations are used as well as ensemble simulations of the regional climate model REMO driven by the coupled global general circulation model ECHAM5/MPI-OM and applying future greenhouse gas (GHG) emission and land degradation scenarios.Der Mittelmeerraum weist eine starke Vulnerabilität gegenüber dem zukünftigen Klimawandel auf, da für diese Region starke klimatische Auswirkungen vorhergesagt werden, aber nur eine geringe Anpassungsfähigkeit besteht. Daher werden präzise Vorhersagen des regionalen oder lokalen Klimawandels benötigt, v.a. für Extremereignisse, welche den Mittelmeer-Lebensraum stark beeinträchtigen. Die vorliegende Studie untersucht zwei Hauptaspekte der Klimavariabilität im Mittelmeerraum: Zum Einen wird das dynamische Downscaling gegenwärtiger und zukünftiger Mittelwerte und Extremereignisse von Temperatur und Niederschlag von der globalen zur regionalen Skala analysiert. Zum Anderen wird eine umfassende Untersuchung von Temperatur- und Niederschlagsextremen samt Unsicherheitsabschätzung und Vergleich unterschiedlicher statistischer Methoden zur Bestimmung von Niederschlagsextremen durchgeführt. Für diese Untersuchungen stehen verschiedene Beobachtungsdaten von CRU, E-OBS und Messstationen sowie Ensemble-Simulationen des regionalen Klimamodells REMO zur Verfügung, das vom gekoppelten globalen “General Circulation Model” ECHAM5/MPI-OM angetrieben wird und zukünftige Treibhausgasemissions- und Landnutzungsänderungs-Szenarien verwendet

Present-Day and Future Global Bottom-Up Ship Emission Inventories Including Polar Routes

We present a global bottom-up ship emission algorithm that calculates fuel consumption, emissions, and vessel traffic densities for present-day (2006) and two future scenarios (2050) considering the opening of Arctic polar routes due to projected sea ice decline. Ship movements and actual ship engine power per individual ship from Lloyd’s Marine Intelligence Unit (LMIU) ship statistics for six months in 2006 and further mean engine data from literature serve as input. The developed SeaKLIM algorithm automatically finds the most probable shipping route for each combination of start and destination port of a certain ship movement by calculating the shortest path on a predefined model grid while considering land masses, sea ice, shipping canal sizes, and climatological mean wave heights. The resulting present-day ship activity agrees well with observations. The global fuel consumption of 221 Mt in 2006 lies in the range of previously published inventories when undercounting of ship numbers in the LMIU movement database (40,055 vessels) is considered. Extrapolated to 2007 and ship numbers per ship type of the recent International Maritime Organization (IMO) estimate (100,214 vessels), a fuel consumption of 349 Mt is calculated which is in good agreement with the IMO total of 333 Mt. The future scenarios show Arctic polar routes with regional fuel consumption on the Northeast and Northwest Passage increasing by factors of up to 9 and 13 until 2050, respectively

User-oriented global predictions of the GPCC drought index for the next decade

Multi-year droughts strongly impact food production and water management. Thus, predictions for the next decade are required for decision makers. This study analyzes the decadal prediction skill of the Global Precipitation Climatology Centre Drought Index (GPCC‑DI) and its components, namely the Standardized Precipitation Index (SPI‑DWD) adapted by the German Meteorological Service (Deutscher Wetterdienst, DWD) and the Standardized Precipitation Evapotranspiration Index (SPEI) within the German global decadal prediction system. The decadal predictions are recalibrated. The prediction skills of the two prediction types ensemble mean predictions and probabilistic predictions are evaluated against those of the commonly applied reference predictions observed climatology and uninitialized simulations. The evaluation of 4‑year mean droughts for the lead-year period 1–4 at 5° spatial resolution shows high prediction skills for the SPEI in the tropics, especially northern Africa, and several heterogeneously distributed hot spots for the SPI‑DWD. The advantage of GPCC‑DI is its global coverage, but it hardly enhances the SPI‑DWD and SPEI skills. The recalibration clearly enhances ensemble mean prediction skills in slightly improving correlations and in strongly reducing standard deviations as well as large conditional biases in decadal predictions. For probabilistic predictions, impacts of conditional biases and recalibration are less prominent. To meet user requirements decadal drought predictions with higher temporal and spatial resolutions are analyzed. 1‑year mean droughts for lead year 1 mostly show smaller prediction skills than 4‑year means because of larger small-scale noise, but some regions reveal improved skills due to regional processes predictable at the 1‑year time scale, e.g. over the western United States. Drought predictions at 2° resolution show similar spatial skill patterns with enhanced fine-scale structures mostly without losing prediction skill. A user-oriented evaluation of the decadal GPCC‑DI prediction for the severe North African drought of 2008–2011 reproduces most observed drought index tendencies in both prediction types, but intensities are often underestimated. Finally, the decadal GPCC‑DI prediction for 2018–2021 presents a drought over North Africa and Arabia and wetting over the Northern Hemisphere in both prediction types. For 2018, predicted patterns are similar but with smoothed intensities. In summary, decadal drought prediction skill depends on the indices, time periods, and areas considered. However, the analyzed drought indices can provide skillful high-resolution information for several future time periods and regions meeting user needs for decadal drought predictions