2018, Wiederhold, Helga, Scheer, Wolfgang, Kirsch, Reinhard, Azizur Rahman, M., Ronczka, Mathias, Szymkiewicz, Adam, Sadurski, A., Jaworska-Szulc, B.

Climate change will result in rising sea level and, at least for the North Sea region, in rising groundwater table. This leads to a new balance at the fresh–saline groundwater boundary and a new distribution of saltwater intrusions with strong regional differentiations. These effects are investigated in several research projects funded by the European Union and the German Federal Ministry of Education and Research (BMBF). Objectives and some results from the projects TOPSOIL and go-CAM are presented in this poster.

2018, Tegen, Ina, Schepanski, Kerstin

Purpose of Review: Climate factors may considerably impact on natural aerosol emissions and atmospheric distributions. The interdependencies of processes within the aerosol-climate system may thus cause climate feedbacks that need to be understood. Recent findings on various major climate impacts on aerosol distributions are summarized in this review. Recent Findings: While generally atmospheric aerosol distributions are influenced by changes in precipitation, atmospheric mixing, and ventilation due to circulation changes, emissions from natural aerosol sources strongly depend on climate factors like wind speed, temperature, and vegetation. Aerosol sources affected by climate are desert sources of mineral dust, marine aerosol sources, and vegetation sources of biomass burning aerosol and biogenic volatile organic gases that are precursors for secondary aerosol formation. Different climate impacts on aerosol distributions may offset each other. Summary: In regions where anthropogenic aerosol loads decrease, the impacts of climate on natural aerosol variabilities will increase. Detailed knowledge of processes controlling aerosol concentrations is required for credible future projections of aerosol distributions.

2018, Steffen, Will, Rockström, Johan, Richardson, Katherine, Lenton, Timothy M., Folke, Carl, Liverman, Diana, Summerhayes, Colin P., Barnosky, Anthony D., Cornell, Sarah E., Crucifix, Michel, Donges, Jonathan F., Fetzer, Ingo, Lade, Steven J., Scheffer, Marten, Winkelmann, Ricarda, Schellnhuber, Hans Joachim

We explore the risk that self-reinforcing feedbacks could push the Earth System toward a planetary threshold that, if crossed, could prevent stabilization of the climate at intermediate temperature rises and cause continued warming on a “Hothouse Earth” pathway even as human emissions are reduced. Crossing the threshold would lead to a much higher global average temperature than any interglacial in the past 1.2 million years and to sea levels significantly higher than at any time in the Holocene. We examine the evidence that such a threshold might exist and where it might be. If the threshold is crossed, the resulting trajectory would likely cause serious disruptions to ecosystems, society, and economies. Collective human action is required to steer the Earth System away from a potential threshold and stabilize it in a habitable interglacial-like state. Such action entails stewardship of the entire Earth System—biosphere, climate, and societies—and could include decarbonization of the global economy, enhancement of biosphere carbon sinks, behavioral changes, technological innovations, new governance arrangements, and transformed social values.

2018, Hattermann, Fred F., Wortmann, Michel, Liersch, Stefan, Toumi, Ralf, Sparks, Nathan, Genillard, Christopher, Schröter, Kai, Steinhausen, Max, Gyalai-Korpos, Miklós, Máté, Kinga, Hayes, Ben, del Rocío Rivas López, María, Rácz, Tibor, Nielsen, Marie R., Kaspersen, Per S., Drews, Martin

Major river and flash flood events have accumulated in Central and Eastern Europe over the last decade reminding the public as well as the insurance sector that climate related risks are likely to become even more damaging and prevalent as climate patterns change. However, information about current and future hydro-climatic extremes is often not available. The Future Danube Model (FDM) is an end-user driven multi-hazard and risk model suite for the Danube region that has been developed to provide climate services related to perils such as heavy precipitation, heat waves, floods, and droughts under recent and scenario conditions. As a result, it provides spatially consistent information on extreme events and natural resources throughout the entire Danube catchment. It can be used to quantify climate risks, to support the implementation of the EU framework directives, for climate informed urban and land use planning, water resources management, and for climate proofing of large scale infrastructural planning including cost benefit analysis. The model suite consists of five individual and exchangeable modules: a weather and climate module, a hydrological module, a risk module, an adaptation module, and a web-based visualization module. They are linked in such a way that output from one module can either be used standalone or fed into subsequent modules. The utility of the tool has been tested by experts and stakeholders. The results show that more and more intense hydrological extremes are likely to occur under climate scenario conditions, e.g. higher order floods may occur more frequently.

2018, Kundzewicz, Zbigniew W., Piniewski, Mikołaj, Mezghani, Abdelkader, Okruszko, Tomasz, Pińskwar, Iwona, Kardel, Ignacy, Hov, Øystein, Szcześniak, Mateusz, Szwed, Małgorzata, Benestad, Rasmus E., Marcinkowski, Paweł, Graczyk, Dariusz, Dobler, Andreas, Førland, Eirik J., O’Keefe, Joanna, Choryński, Adam, Parding, Kajsa M., Haugen, Jan Erik

The present paper offers a brief assessment of climate change and associated impact in Poland, based on selected results of the Polish–Norwegian CHASE-PL project. Impacts are examined in selected sectors, such as water resources, natural hazard risk reduction, environment, agriculture and health. Results of change detection in long time series of observed climate and climate impact variables in Poland are presented. Also, projections of climate variability and change are provided for time horizons of 2021–2050 and 2071–2100 for two emission scenarios, RCP4.5 and RCP8.5 in comparison with control period, 1971–2000. Based on climate projections, examination of future impacts on sectors is also carried out. Selected uncertainty issues relevant to observations, understanding and projections are tackled as well.

2018, Chepkoech, W., Mungai, N.W., Stöber, S., Bett, H.K., Lotze-Campen, H.

Purpose: Understanding farmers’ perceptions of how the climate is changing is vital to anticipating its impacts. Farmers are known to take appropriate steps to adapt only when they perceive change to be taking place. This study aims to analyse how African indigenous vegetable (AIV) farmers perceive climate change in three different agro-climatic zones (ACZs) in Kenya, identify the main differences in historical seasonal and annual rainfall and temperature trends between the zones, discuss differences in farmers’ perceptions and historical trends and analyse the impact of these perceived changes and trends on yields, weeds, pests and disease infestation of AIVs. Design/methodology/approach: Data collection was undertaken in focus group discussions (FGD) (N = 211) and during interviews with individual farmers (N = 269). The Mann–Kendall test and regression were applied for trend analysis of time series data (1980-2014). Analysis of variance and least significant difference were used to test for differences in mean rainfall data, while a chi-square test examined the association between farmer perceptions and ACZs. Coefficient of variation expressed as a percentage was used to show variability in mean annual and seasonal rainfall between the zones. Findings: Farmers perceived that higher temperatures, decreased rainfall, late onset and early retreat of rain, erratic rainfall patterns and frequent dry spells were increasing the incidences of droughts and floods. The chi-square results showed a significant relationship between some of these perceptions and ACZs. Meteorological data provided some evidence to support farmers’ perceptions of changing rainfall. No trend was detected in mean annual rainfall, but a significant increase was recorded in the semi-humid zone. A decreasing maximum temperature was noted in the semi-humid zone, but otherwise, an overall increase was detected. There were highly significant differences in mean annual rainfall between the zones. Farmers perceived reduced yields and changes in pest infestation and diseases in some AIVs to be prevalent in the dry season. This study’s findings provide a basis for local and timely institutional changes, which could certainly help in reducing the adverse effects of climate change. Originality/value: This is an original research paper and the historical trends, farmers’ perceptions and effects of climate change on AIV production documented in this paper may also be representative of other ACZs in Kenya.

2018, Döll, Petra, Trautmann, Tim, Gerten, Dieter, Müller Schmied, Hannes, Ostberg, Sebastian, Saaed, Fahad, Schleussner, Carl-Friedrich

To support implementation of the Paris Agreement, the new HAPPI ensemble of 20 bias-corrected simulations of four climate models was used to drive two global hydrological models, WaterGAP and LPJmL, for assessing freshwater-related hazards and risks in worlds approximately 1.5 °C and 2 °C warmer than pre-industrial. Quasi-stationary HAPPI simulations are better suited than transient CMIP-like simulations for assessing hazards at the two targeted long-term global warming (GW) levels. We analyzed seven hydrological hazard indicators that characterize freshwater-related hazards for humans, freshwater biota and vegetation. Using a strict definition for significant differences, we identified for all but one indicator that areas with either significantly wetter or drier conditions (calculated as percent changes from 2006–2015) are smaller in the 1.5 °C world. For example, 7 day high flow is projected to increase significantly on 11% and 21% of the global land area at 1.5 °C and 2 °C, respectively. However, differences between hydrological hazards at the two GW levels are significant on less than 12% of the area. GW affects a larger area and more people by increases—rather than by decreases—of mean annual and 1-in-10 dry year streamflow, 7 day high flow, and groundwater recharge. The opposite is true for 7 day low flow, maximum snow storage, and soil moisture in the driest month of the growing period. Mean annual streamflow shows the lowest projected percent changes of all indicators. Among country groups, low income countries and lower middle income countries are most affected by decreased low flows and increased high flows, respectively, while high income countries are least affected by such changes. The incremental impact between 1.5 °C and 2 °C on high flows would be felt most by low income and lower middle income countries, the effect on soil moisture and low flows most by high income countries.

2018, Vicedo-Cabrera, Ana Maria, Guo, Yuming, Sera, Francesco, Huber, Veronika, Schleussner, Carl-Friedrich, Mitchell, Dann, Tong, Shilu, de Sousa Zanotti Stagliorio Coelho, Micheline, Saldiva, Paulo Hilario Nascimento, Lavigne, Eric, Matus Correa, Patricia, Valdes Ortega, Nicolas, Kan, Haidong, Osorio, Samuel, Kyselý, Jan, Urban, Aleš, Jaakkola, Jouni J. K., Ryti, Niilo R. I., Pascal, Mathilde, Goodman, Patrick G., Zeka, Ariana, Michelozzi, Paola, Scortichini, Matteo, Hashizume, Masahiro, Honda, Yasushi, Hurtado-Diaz, Magali, Cruz, Julio, Seposo, Xerxes, Kim, Ho, Tobias, Aurelio, Íñiguez, Carmen, Forsberg, Bertil, Åström, Daniel Oudin, Ragettli, Martina S., Röösli, Martin, Guo, Yue Leon, Wu, Chang-fu, Zanobetti, Antonella, Schwartz, Joel, Bell, Michelle L., Dang, Tran Ngoc, Do Van, Dung, Heaviside, Clare, Vardoulakis, Sotiris, Hajat, Shakoor, Haines, Andy, Armstrong, Ben, Ebi, Kristie L., Gasparrini, Antonio

The Paris Agreement binds all nations to undertake ambitious efforts to combat climate change, with the commitment to “hold warming well below 2 °C in global mean temperature (GMT), relative to pre-industrial levels, and to pursue efforts to limit warming to 1.5 °C”. The 1.5 °C limit constitutes an ambitious goal for which greater evidence on its benefits for health would help guide policy and potentially increase the motivation for action. Here we contribute to this gap with an assessment on the potential health benefits, in terms of reductions in temperature-related mortality, derived from the compliance to the agreed temperature targets, compared to more extreme warming scenarios. We performed a multi-region analysis in 451 locations in 23 countries with different climate zones, and evaluated changes in heat and cold-related mortality under scenarios consistent with the Paris Agreement targets (1.5 and 2 °C) and more extreme GMT increases (3 and 4 °C), and under the assumption of no changes in demographic distribution and vulnerability. Our results suggest that limiting warming below 2 °C could prevent large increases in temperature-related mortality in most regions worldwide. The comparison between 1.5 and 2 °C is more complex and characterized by higher uncertainty, with geographical differences that indicate potential benefits limited to areas located in warmer climates, where direct climate change impacts will be more discernible.

2018, Lobanova, A., Liersch, S., Nunes, J.P., Didovets, I., Stagl, J., Huang, S., Koch, H., Rivas López, M.D.R., Maule, C.F., Hattermann, F., Krysanova, V.

Study region: To provide a picture of hydrological impact of climate change across different climatic zones in Europe, this study considers eight river basins: Tagus in Iberian Peninsula; Emån and Lule in Scandinavia; Rhine, Danube and Teteriv in Central and Eastern Europe; Tay on the island of Great Britain and Northern Dvina in North-Eastern Europe. Study focus: In this study the assessment of the impacts of moderate and high-end climate change scenarios on the hydrological patterns in European basins was conducted. To assess the projected changes, the process-based eco-hydrological model SWIM (Soil and Water Integrated Model) was set up, calibrated and validated for the basins. The SWIM was driven by the bias-corrected climate projections obtained from the coupled simulations of the Global Circulation Models and Regional Climate Models. New hydrological insights for the region: The results show robust decreasing trends in water availability in the most southern river basin (Tagus), an overall increase in discharge in the most northern river basin (Lule), increase in the winter discharge and shift in seasonality in Northern and Central European catchments. The impacts of the high-end climate change scenario RCP 8.5 continue to develop until the end of the century, while those of the moderate climate change scenario RCP 4.5 level-off after the mid-century. The results of this study also confirm trends, found previously with mostly global scale models.

2018, Liersch, S., Tecklenburg, J., Rust, H., Dobler, A., Fischer, M., Kruschke, T., Koch, H., Hattermann, F.F.

Climate simulations are the fuel to drive hydrological models that are used to assess the impacts of climate change and variability on hydrological parameters, such as river discharges, soil moisture, and evapotranspiration. Unlike with cars, where we know which fuel the engine requires, we never know in advance what unexpected side effects might be caused by the fuel we feed our models with. Sometimes we increase the fuel's octane number (bias correction) to achieve better performance and find out that the model behaves differently but not always as was expected or desired. This study investigates the impacts of projected climate change on the hydrology of the Upper Blue Nile catchment using two model ensembles consisting of five global CMIP5 Earth system models and 10 regional climate models (CORDEX Africa). WATCH forcing data were used to calibrate an eco-hydrological model and to bias-correct both model ensembles using slightly differing approaches. On the one hand it was found that the bias correction methods considerably improved the performance of average rainfall characteristics in the reference period (1970-1999) in most of the cases. This also holds true for non-extreme discharge conditions between Q20 and Q80. On the other hand, bias-corrected simulations tend to overemphasize magnitudes of projected change signals and extremes. A general weakness of both uncorrected and bias-corrected simulations is the rather poor representation of high and low flows and their extremes, which were often deteriorated by bias correction. This inaccuracy is a crucial deficiency for regional impact studies dealing with water management issues and it is therefore important to analyse model performance and characteristics and the effect of bias correction, and eventually to exclude some climate models from the ensemble. However, the multi-model means of all ensembles project increasing average annual discharges in the Upper Blue Nile catchment and a shift in seasonal patterns, with decreasing discharges in June and July and increasing discharges from August to November.