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Important hydrological changes are observed in Serbia, as well as in many parts of the world. Many national and international projects and studies address climate change and its impact on water resources. Some focus solely on the impact of climate change, while others also assess the impact of land use changes and/or changes in human use of water. Due to differences in climate change and human activities, the different climate and hydrological trends are obtained for the different regions in Serbia. This paper presents the past longterm temperature, precipitation and river discharge trends across Serbia. Second, more important aim of the research, is to assess and forecast average relationships between an increase in air temperature and changes in river discharges and precipitation. This relation could help us to find appropriate regional climate and hydrological models. Even within a single catchment, depending on the regional models used, the initial and other assumptions made, and the impacts assessed, the differences between the results can be small but often significant, too. The reliability of the projections receives little or no consideration. This paper also discusses this topic and attempts to provide some guidelines. [ABSTRACT FROM AUTHOR]

Climate change impact assessment on meteorological variables involves large uncertainties as a result of incomplete knowledge on the future greenhouse gas concentrations and climate model physics, next to the inherent internal variability of the climate system. Given that the alteration in greenhouse gas concentrations is the driver for the change, one expects the impacts to be highly dependent on the considered greenhouse gas scenario (GHS). In this study, we denote this behavior as GHS sensitivity. Due to the climate model related uncertainties, this sensitivity is, at local scale, not always that strong as expected. This paper aims to study the GHS sensitivity and its contributing role to climate scenarios for a case study in Belgium. An ensemble of 160 CMIP5 climate model runs is considered and climate change signals are studied for precipitation accumulation, daily precipitation intensities and wet day frequencies. This was done for the different seasons of the year and the scenario periods 2011–2040, 2031–2060, 2051–2081 and 2071–2100. By means of variance decomposition, the total variance in the climate change signals was separated in the contribution of the differences in GHSs and the other model-related uncertainty sources. These contributions were found dependent on the variable and season. Following the time of emergence concept, the GHS uncertainty contribution is found dependent on the time horizon and increases over time. For the most distinct time horizon (2071–2100), the climate model uncertainty accounts for the largest uncertainty contribution. The GHS differences explain up to 18% of the total variance in the climate change signals. The results point further at the importance of the climate model ensemble design, specifically the ensemble size and the combination of climate models, whereupon climate scenarios are based. The numerical noise, introduced at scales smaller than the skillful scale, e.g. at local scale, was not considered in this study. [ABSTRACT FROM AUTHOR]

This paper analyzes the historical precipitation and temperature trends and the future climate projections with reference to the northern part of Tuscany (Italy). The trends are identified and quantified at monthly and annual scale at gauging stations with data collected for long periods (60–90 years). An ensemble of 13 Regional Climate Models (RCMs), based on two Representative Concentration Pathways (RCP4.5 and RCP8.5), was then used to assess local scale future precipitation and temperature projections and to represent the uncertainty in the results. The historical data highlight a general decrease of the annual rainfall at a mean rate of 22 mm per decade but, in many cases, the tendencies are not statistically significant. Conversely, the annual mean temperature exhibits an upward trend, statistically significant in the majority of cases, with a warming rate of about 0.1 °C per decade. With reference to the model projections and the annual precipitation, the results are not concordant; the deviations between models in the same period are higher than the future changes at medium- (2031–2040) and long-term (2051–2060) and highlight that the model uncertainty and variability is high. According to the climate model projections, the warming of the study area is unequivocal; a mean positive increment of 0.8 °C at medium-term and 1.1 °C at long-term is expected with respect to the reference period (2003–2012) and the scenario RCP4.5; the increments grow to 0.9 °C and 1.9 °C for the RCP8.5. Finally, in order to check the observed climate change signals, the climate model projections were compared with the trends based on the historical data. A satisfactory agreement is obtained with reference to the precipitation; a systematic underestimation of the trend values with respect to the models, at medium- and long-term, is observed for the temperature data. [ABSTRACT FROM AUTHOR]

The present paper addresses driving mechanisms of global monsoon (GM) variability and outstanding issues in GM science. This is the second synthesis of the PAGES GM Working Group following the first synthesis “The Global Monsoon across Time Scales: coherent variability of regional monsoons” published in 2014 (Climate of the Past, 10, 2007–2052). Here we introduce the GM as a planetary scale circulation system and give a brief accounting of why it exhibits regional structure. The primary driver of the GM is solar insolation, and the specific features in the underlying surface, such as land-sea distribution, topography, and oceanic circulations, are mainly responsible for the differences among regional monsoon systems. We then analyze the monsoon formation mechanisms, together with the major processes that drive monsoon variations at various timescales, including external forcings and internal feedbacks. On long time scales, external forcings often induce variability on a global scale, whereas short-term variability in regional monsoon systems is usually caused by internal feedbacks within the climate system. Finally, a number of debatable issues are discussed, with an emphasis on time scales beyond the instrumental record. These include the dual nature of the monsoon as wind and rain, the meaning of oxygen isotope in hydrological cycle, in particular of speleothem δ 18 O, the role of ice-sheet in monsoon variations, etc. In general, the GM as a system comprises a hierarchy of regional and local monsoons with various degrees of similarity, though all show coherent variability driven by a common solar forcing. The goal of the GM concept, therefore, is by no means to replace or diminish research on the regional monsoons, but to help dissect the mechanisms and controlling factors of monsoon variability at various temporal-spatial scales. [ABSTRACT FROM AUTHOR]

Loess Plateau has great uncertainty on drought occurrence due to climate change. This paper analyzes the evolution of precipitation, potential evapotranspiration and standardized precipitation evapotranspiration index (SPEI) based on the Coupled Model Inter-comparison Project Phase 5 (CMIP5) data and regional downscaling model (RegCM4.0). Results indicate that, under RCP2.6 Scenario, the precipitation will increase significantly (5% confidence level) at the rate of 16.40 mm/10 a. However, the potential evapotranspiration is showing non-significant decreasing trend at the rate of 2.16 mm/10 a. Moreover, the SPEI will decrease in the south and northernmost area and increase in the central northern area of Loess Plateau. Under RCP8.5 Scenario, the precipitation will increase significantly (5% confidence level) at the rate of 19.12 mm/10 a. The potential evapotranspiration will non-significantly decrease at the rate of 2.16 mm/10 a and the SPEI is showing increasing trend almost in the whole Loess Plateau. Generally, Loess Plateau is becoming wetter in the central part under RCP2.6 Scenario and the wet area will be enlarged to almost the whole plateau under RCP8.5 Scenario. Based on the results, the water resources will increase under global warming, which may alleviate the water scarcity issue in the Loess Plateau. [ABSTRACT FROM AUTHOR]

This study evaluates the effect on the availability of water resources for agriculture of expected future changes in precipitation and temperature distributions in north-western Africa. It also puts forward some locally derived adaptation strategies to climate change that can have a positive impact on water resources in the Chtouka Aït Baha region. Historical baselines of precipitation and temperature were derived using satellite data respectively from CHIRPS and CRU, while future projections of temperature and precipitation were extracted from the Coordinated Regional Climate Downscaling Experiment database (CORDEX). Projections were also generated for two future periods (2030–2049 and 2080–2099) under two Representative Concentration Pathways: RCP4.5 and RCP8.5. Regional climate models and satellite data outputs were evaluated by calculating their bias and RMSE against historical baseline and observed data. Under the RCP8.5 scenario, temperature in the region shows an increase by 2 °C for the 2030–2049 time period, and by 4 to 5 °C towards the end of the 21st century. According to the RCP4.5 scenario, precipitation shows a reduction of 10 to 30% for the period 2030–2049, up to 60% for 2080–2099. Outputs from the climate change projections were used to force the HEC-HMS hydrological model. Simulation results indicate that water deficit at basin level will likely triple towards 2050 due to increase in water demand and decrease in aquifer recharge and dam storage. This alarming situation, in a country that already suffers from water insecurity, emphasizes the need for more efforts to implement climate change adaptation measures. This paper presents an assessment of 38 climate change adaptation measures according to several criteria. The evaluation shows that measures affecting the management of water resources have the highest benefit-to-efforts ratio, which indicates that decision makers and stakeholders should increasingly focus their efforts on management measures. [ABSTRACT FROM AUTHOR]

The assessment of future precipitation variations prevailing in an area is essential for the research regarding climate and climate change. The current paper focuses on 3 selected areas in Greece that present different climatic characteristics due to their location and aims to assess and compare the future variation of annual and seasonal precipitation. Future precipitation data from the ENSEMBLES anthropogenic climate-change (ACC) global simulations and the Climate version of the Local Model (CLM) were obtained and analyzed. The climate simulations were performed for the future periods 2021–2050 and 2071–2100 under the A1B and B1 scenarios. Mann–Kendall test was applied to investigate possible trends. Spatial distribution of precipitation was performed using a combination of dynamic and statistical downscaling techniques and Kriging method within ArcGIS 10.2.1. The results indicated that for both scenarios, reference periods and study areas, precipitation is expected to be critically decreased. Additionally, Mann–Kendall test application showed a strong downward trend for every study area. Furthermore, the decrease in precipitation for the Ardas River basin characterized by the continental climate will be tempered, while in the Sperchios River basin it will be smoother due to the influence of some minor climatic variations in the basins' springs in the highlands where milder conditions occur. Precipitation decrease in the Geropotamos River basin which is characterized by Mediterranean climate will be more vigorous. B1 scenario appeared more optimistic for the Ardas and Sperchios River basins, while in the Geropotamos River basin, both applied scenarios brought similar results, in terms of future precipitation response. [ABSTRACT FROM AUTHOR]

Precipitation is one of the most important climate variables which can impact the urban water and urban flooding. Thus, knowledge of precipitation and precipitation extremes is important to manage urban water and to design urban drainage infrastructure to reduce the urban flooding. This paper presented trends in precipitation and precipitation extremes in Ho Chi Minh City for the 1980-2013 period based on the precipitation data obtained from nine rain gauges. Non-parametric test, i.e. Mann-Kendall test, was used for trend analysis, and the precipitation extremes indices were used to calculate the extreme events. The results indicated that the precipitation has increasing trend in the northwest part of the city and decreasing trend in the southeast part of the city in the 1980-2013 period. In addition, the precipitation and precipitation extremes had generally increasing trends. The results obtained in this study can be used for urban water management and sustainable urban drainage system in Ho Chi Minh City. [ABSTRACT FROM AUTHOR]

The most important anthropogenic influences on climate are the emissions, changes in land use, such as urbanization aural areasnd agriculture. The urban environment has distinctive bioclimatical factors in relation to rural areas. The process of urbanization alters natural surface and atmospheric conditions. Urban areas are characteristic by increased rainwater surface runoff, increased temperatures and decreased evaporation. Exactly evaporation warms the rural surface more than the urban. The paper concerns on the impacts of urbanization that are evaluated by observations in cities with those in rural areas – not so populated and with smaller built areas. We use and asses the difference between trends in monthly average temperatures and trends in monthly precipitations in the cities and the corresponding trends in rural areas. For the trend analysis, the Mann-Kendall nonparametric test is used. Our results show differences in trends in villages and cities. Observed are increased trends in temperature and decreased trends in precipitation due to urban and land-use changes. [ABSTRACT FROM AUTHOR]

Summary The climate elasticity of runoff is an important indicator that is used to quantify the relationship between changes in runoff and changes in climate variables. It is a function of both climate and catchment characteristics. Recently, Yang and Yang (2011) proposed an analytical derivation of climate elasticity (YY2011), in which a parameter n was used to represent the impact of the catchment characteristics. In China, both climate and catchment characteristics have large spatial variations. To understand the spatial variation of hydrologic response to climate change, this paper divided China into 210 catchments, further calculated the parameter n , and then estimated the climate elasticity and evaluated the contribution of climate change to runoff for each catchment. The results show that n ranges from 0.4 to 3.8 (with a mean of 1.3 and a standard deviation of 0.6), which has a logarithmic relationship with catchment slope; the precipitation elasticity ranges from 1.1 to 4.8 (with a mean of 1.9 and a standard deviation of 0.6), which shows a large regional variation, smaller values (1.1–2.0) mainly appearing in Southern China, the Songhua River basin and the Northwest, and larger values (2.1–4.8) mainly appearing in the Hai River basin, the Liao River basin and the Yellow River basin. In addition, climate contribution to runoff exhibits a large regional variation, the largest positive values (1.1–3.1%/a) occurring in the Northwest, the largest negative values (−1.0 to −0.5%/a) occurring in the Hai River basin and the middle reach of the Yellow River basin. In theory, the YY2011 method is a first-order approximation. The approximation underestimates the precipitation ( P ) contribution to runoff when P increases and overestimates that when P decreases, and the relative error has a median of ∼3% and a maximum of ∼20% when 10% precipitations change in those catchments of China. [ABSTRACT FROM AUTHOR]

The total glacial area of the Cordillera Blanca, Peru, has shrunk by more than 30% in the period of 1930 to the present with a marked glacier retreat also in the recent decades. The aim of this paper is to assess local air temperature and precipitation changes in the Cordillera Blanca and to discuss how these variables could have affected the observed glacier retreat between the 1980s and present. A unique data set from a large number of stations in the region of the Cordillera Blanca shows that after a strong air temperature rise of about 0.31°C per decade between 1969 and 1998, a slowdown in the warming to about 0.13°C per decade occurred for the 30years from 1983 to 2012. Additionally, based on data from a long-term meteorological station, it was found that the freezing line altitude during precipitation days has probably not increased significantly in the last 30years. We documented a cooling trend for maximum daily air temperatures and an increase in precipitation of about 60mm/decade since the early 1980s. The strong increase in precipitation in the last 30years probably did not balance the increase of temperature before the 1980s. It is suggested that recent changes in temperature and precipitation alone may not explain the glacial recession within the thirty years from the early 1980s to 2012. Glaciers in the Cordillera Blanca may be still reacting to the positive air temperature rise before 1980. Especially small and low-lying glaciers are characterised by a serious imbalance and may disappear in the near future. [ABSTRACT FROM AUTHOR]