Decrease In Annual Precipitation Research Articles

Countrywide climate features during recorded climate-related disasters

Climate-related disasters cause substantial disruptions to human societies. With climate change, many extreme weather and climate events are expected to become more severe and more frequent. The International Disaster Database (EM-DAT) records climate-related disasters associated with observed impacts such as affected people and economic damage on a country basis. Although disasters are classified into different meteorological categories, they are usually not linked to observed climate anomalies. Here, we investigate countrywide climate features associated with disasters that have occurred between 1950 and 2015 and have been classified as droughts, floods, heat waves, and cold waves using superposed epoch analysis. We find that disasters classified as heat waves are associated with significant countrywide increases in annual mean temperature of on average 0.13 ∘C and a significant decrease in annual precipitation of 3.2%. Drought disasters show positive temperature anomalies of 0.08 ∘C and a 4.8 % precipitation decrease. Disasters classified as droughts and heat waves are thus associated with significant annual countrywide anomalies in both temperature and precipitation. During years of flood disasters, precipitation is increased by 2.8 %. Cold wave disasters show no significant signal for either temperature or precipitation. We further find that climate anomalies tend to be larger in smaller countries, an expected behavior when computing countrywide averages. In addition, our results suggest that extreme weather disasters in developed countries are typically associated with larger climate anomalies compared to developing countries. This effect could be due to different levels of vulnerability, as a climate anomaly needs to be larger in a developed country to cause a societal disruption. Our analysis provides a first link between recorded climate-related disasters and observed climate data, which is an important step towards linking climate and impact communities and ultimately better constraining future disaster risk.

Dynamics of erosion-accumulation processes along the stream bed of Turiya River (Kovel hydropost)

The article reflects the results of the study of deformations of the stream bed of the Turiya River (Kovel Hydropost, hydro range No. 5) during 1983–2018. For this purpose, multiple cross-sections of the channel and various combined flow curves were constructed and analyzed, the levels of water in the river, the relationships between the course of erosion-accumulation processes along the course and the dynamics of natural and anthropogenic factors are revealed. The information base of the study was the theoretical basis of the doctrine of channel processes, which are substantiated in the works of foreign and Ukrainian scientists, the materials of our own observations, data from the Volyn Center for Hydrology and Meteorology (hereinafter VCGM). In the process of solving the tasks, the methods of comparative analysis, synthesis, graphic, mathematical and statistical methods were applied; the system approach was applied. During the study it was established that during the specified time interval in the stream bed there was an alternation of erosion and accumulation processes, which was expressed by the alternation of periods of some erosion of the stream bed and its siltation. The transverse profiles of the Turiya stream bed indicate that during the period 1983–1988, mainly accumulative processes prevailed in the channel, and in the following period (1988–2008) they changed to erosion ones. In recent years, rechargeable processes have become dominant and the profile of the stream bed in 2018 has come closer to its stream bed in 1988. The flow and water level curves of Turiya confirm our conclusions about trends in erosion-accumulation processes along the stream bed. During the periods 1983–1988 and 1996–2000, the accumulation processes dominated, and at the interval of time from 1988 to 1996 and in 2000–2008 erosion processes dominated. The 2009, 2012, 2013, 2014, 2017 curves are in almost one field, which attests to the stability of the Turiya River over the last decade. The development of channel deformations depends, mainly, on the hydrological regime of the river. The dynamics of erosion-accumulation processes along the river Turiya is consistent with the long-term regime of its maximum runoff: in the 80-ies of the last century a significant fall in the values of maximum discharge (some decrease in annual precipitation, the influence of the Kovel reservoir) was observed, which led to their erosion. Compared to this time period, around the 1990s and during the 2000s, the values of maximum discharge increased slightly. As a consequence, the eroding ability of the watercourse during floods and freshets increased, which slightly increased the cross-sectional area of the channel. In the last four years, the values of maximum discharge have been significantly lower than normal, and as a result erosion processes have weakened. Reduction of the maximum discharge of the Turiya River, absence of runoff during the 2015–2018 boundary, dominance of accumulative processes in the channel leads to eutrophication of the watercourse, which, in turn, reduces its transport capacity and contributes to the further accumulation of solids. If this trend continues in the future, then the risks of flooding the Turiya floodplains in the event of heavy floods or freshets will increase. Keywords: Volyn region, hydrological regime, hydropost, water flow and water level curves, transverse profile of river bed, Turiya River, surface runoff, stream bed deformations.

Landscape-level spatiotemporal patterns of Dendrolimus punctatus Walker and its driving forces: evidence from a Pinus massoniana forest

The spatiotemporal patterns and strength of Dendrolimus punctatus Walker attacks were identified at the landscape level. Climate factors influenced pest damage more than stand or topographic factors. Dendrolimus punctatus Walker (Lepidoptera: Lasiocampidae) routinely infests pine species in southern China and inflicts heavy damage on resources or monetary earnings. Evidence is required to facilitate a better understanding of spatiotemporal infestation patterns at the landscape level and the influence of various factors on its outbreaks from multiple spheres. We quantified the landscape-level spatiotemporal pattern of D. punctatus occurrence and examined the impacts of climate, stand and topographical factors on pest infestations in a Pinus massoniana natural forest in a mixed world heritage site in southeastern China. Our findings indicated that pest infestations had a relatively strong temporal continuity and a weak spatially aggregated distribution at a landscape level. Multivariate statistical analysis showed that climate variables had a greater influence on the degree of damage caused by D. punctatus infestations than stand or topographical variables. A decrease in annual average precipitation or humidity may cause an increased risk of pest outbreaks.

Using RothC Model to Simulate Soil Organic Carbon Stocks under Different Climate Change Scenarios for the Rangelands of the Arid Regions of Southern Iran

Soil organic carbon (SOC) is strongly influenced by climate change, and it is believed that increased temperatures might enhance the release of CO2 with higher emission into the atmosphere. Appropriate models may be used to predict the changes of SOC stock under projected future scenarios of climate change. In this investigation, the RothC model was run for a period of 36 years under climate scenarios namely: P (no climate change) as well as CCH1 and CCH2 (climate change scenarios) in the arid rangelands of Ghir–O-Karzin’s BandBast in southern Iran. Model results have shown that after 11 years (2014–25), SOC stock decreased by 3.05% under the CCH1 scenario (with a projected annual precipitation decrease by 6.69% and mean annual temperature increase by 9.96%) and by 0.23% under the P scenario. In CCH2, with further decreases in rainfall (10.93%) and increase in temperature (12.53%) compared to CCH1, the model predicted that the SOC stock during the 25 years (2025–50) was reduced by 2.36% and 3.53% under the CCH1 and CCH2 scenario respectively. According to model predictions, with future climatic conditions (higher temperatures and lower rainfall) the decomposition rate may increase resulting in higher losses of soil organic carbon from the soil matrix. The result from this investigation may also be used for developing management techniques to be practiced in the other arid rangelands of Iran with similar conditions.

Suspended sediment yield and climate change in Kamchatka, Far East of Russia

Abstract. Key factors of sediment yield formation and variability in the Kamchatsky Krai are relief characteristics and climate (especially precipitation). The last research in climate change in Kamchatka demonstrates climate warming – mean annual air temperature has increased on 1.5 ∘C during the period from 1951 to 2009 in average (the maximum increase was revealed in the west of Kamchatka and in the Kamchatka River valley, the minimum one – in the extreme south and north). Decrease of annual precipitation was observed at the same period. In addition frequency and intensity of precipitation is growing. Thereby described climate changes in Kamchatka influence on sediment yield characteristics directly (influence of precipitation on surface washout formation) and indirectly (through water runoff and hydrological regime of rivers changes). Analysis of spatio-temporal variability in suspended sediment yield demonstrated decrease since late 1970–early 1980 in the most part of rivers in the Kamchatsky Krai. Revealed fluctuations demonstrate very good coincidence with precipitation amount variability. Decrease of precipitation leads to corresponding diminution of rainfall erosive factor in the territory which is the key factor of suspended sediment yield formation and variability in rivers in the Kamchatsky Krai. The value of reduction varies from 1 % to 45 % and involves decrease of erosion rates in the territory. Thereby climate change influences on suspended sediment yield in multiple-valued way. Income of friable volcanic deposits on the catchment surface is the key factor of suspended sediment yield formation and variability in some river basins under the impact of volcanic eruptions, and in combination with raising precipitation it can lead to catastrophic increase of sediment yield.

Differing Impacts of Black Carbon and Sulfate Aerosols on Global Precipitation and the ITCZ Location via Atmosphere and Ocean Energy Perturbations

AbstractThis study explores the effects of black carbon (BC) and sulfate (SO4) on global and tropical precipitation with a climate model. Results show that BC causes a decrease in global annual mean precipitation, consisting of a large negative tendency of a fast precipitation response scaling with instantaneous atmospheric absorption and a small positive tendency of a slow precipitation response scaling with the BC-caused global warming. SO4 also causes a decrease in global annual mean precipitation, which is dominated by a slow precipitation response corresponding to the surface cooling caused by SO4. BC causes a northward shift of the intertropical convergence zone (ITCZ), mainly through a fast precipitation response, whereas SO4 causes a southward shift of the ITCZ through a slow precipitation response. The displacements of the ITCZ caused by BC and SO4 are found to linearly correlate with the corresponding changes in cross-equatorial heat transport in the atmosphere, with a regression coefficient of about −3° PW−1, implying that the ITCZ shifts occur as manifestations of the atmospheric cross-equatorial heat transport changes in response to the BC and SO4 forcings. The atmospheric cross-equatorial heat transport anomaly caused by BC is basically driven by the BC-induced interhemispheric contrast in instantaneous atmospheric absorption, whereas the atmospheric cross-equatorial heat transport anomaly caused by SO4 is mostly attributable to the response of evaporation. It is found that a slab-ocean model exaggerates the cross-equatorial heat transport response in the atmosphere and the ITCZ shift both for BC and SO4, as compared with an ocean-coupled model. This underscores the importance of using an ocean-coupled model in modeling studies of the tropical climate response to aerosols.

Effect of rapid urbanization on Mediterranean karstic mountainous drainage basins

Transformation of permeable natural areas into impervious surfaces (e.g. roads, parking lots, and buildings) is altering the watershed response to precipitation, generating bigger runoff volumes with increased peak discharges. The runoff travels faster to the watershed outlet, accumulates, and might cause flooding. Urban areas are affected by flooding, with consequences that might result in severe economic damage and even hazard to life. The paper will estimate the effect of rapid urbanization on runoff and on groundwater recharge. The model includes the Shiloh catchment basin located in a karstic mountainous terrain in Israel for a time period of rapid development from 1978 to 2018. Evaluation of surface permeability was based on land-use classifications from Landsat datasets using the Q-GIS 3.4 platform. Multiyear runoff coefficient estimation was calculated based on annual runoff and rainfall series. The evaluation suggests natural permeable areas were constantly declining from about 400 km2 (nearby 100% of the Shiloh basin) in 1978 to about 100 km2 in 2018 and that nonpermeable areas increased to 95 km2 and semi-permeable areas to 250 km2. Despite annual precipitation decrease during the last two decades, the annual runoff coefficient has a pronounced tendency to increase. This research suggests that the anthropogenic impact on the Shiloh basin and, hence, similar watersheds encourages runoff accumulation, resulting in extreme flood events recurrence while significantly reducing the groundwater recharge.

Predicting the vulnerability of seasonally-flooded wetlands to climate change across the Mediterranean Basin

Wetlands have been declining worldwide over the last century with climate change becoming an additional pressure, especially in regions already characterized by water deficit. This paper investigates how climate change will affect the values and functions of Mediterranean seasonally-flooded wetlands with emergent vegetation. We simulated the future evolution of water balance, wetland condition and water volumes necessary to maintain these ecosystems at mid- and late- 21st century, in 229 localities around the Mediterranean basin. We considered future projections of the relevant climatic variables under two Representative Concentration Pathway scenarios assuming a stabilization (RCP4.5) or increase (RCP 8.5) of greenhouse gases emissions. We found similar increases of water deficits at most localities around 2050 under both RCP scenarios. By 2100, however, water deficits under RCP 8.5 are expected to be more severe and will impact all localities. Simulations performed under current conditions show that 97% of localities could have wetland habitats in good state. By 2050, however, this proportion would decrease to 81% and 68% under the RCP 4.5 and RCP 8.5 scenarios, respectively, decreasing further to 52% and 27% by 2100. Our results suggest that wetlands can persist with up to a 400 mm decrease in annual precipitation. Such resilience to climate change is attributed to the semi-permanent character of wetlands (lower evaporation on dry ground) and their capacity to act as reservoir (higher precipitation expected in some countries during winter). Countries at highest risk of wetland degradation and loss are Algeria, Morocco, Portugal and Spain. Degradation of wetlands with emergent vegetation will negatively affect their biodiversity and the services they provide by eliminating animal refuges and primary resources for industry and tourism. A sound strategy to preserve these wetlands would consist of proactive management to reduce non-climate stressors.

Accelerated glacier mass loss (2011–2016) over the Puruogangri ice field in the inner Tibetan Plateau revealed by bistatic InSAR measurements

The temporal variation of glacier mass balance during recent years remains poorly known for the mountain glaciers in the inner Tibetan Plateau (ITP), due to the lack of field measurements. In this study, we retrieved the annual glacier mass balance of the Puruogangri ice field, which is the largest modern ice mass in the ITP, by differencing multi-temporal digital elevation models (DEMs) generated with five pairs of TanDEM-X bistatic interferometric synthetic aperture radar (InSAR) images acquired between April 2011 and January 2016. We compared the TanDEM-X DEMs in January and April 2012 to estimate the X-band radar penetration depth difference (0.61 ± 0.06 m), which enabled systematic bias correction in the estimation of annual glacier mass balance. The observed mass balance reveals a glacier mass gain of 0.44 ± 0.10 m w.e. yr−1 in 2011–12, which was followed by accelerated glacier mass loss in 2012–16. Glacier mass balances of −0.13 ± 0.03, −0.34 ± 0.06, and − 0.52 ± 0.10 m w.e. yr−1 were estimated for the periods of 2012–13, 2013–14, and 2014–16, respectively. This accelerating trend of glacier mass loss is likely caused by the continuous decrease in annual precipitation, according to the climate data recorded by adjacent meteorological stations. This study demonstrates that repeated bistatic InSAR measurement is a promising method for monitoring glacier elevation change and mass balance at regular intervals.

THE ROLE OF FOREST ECOSYSTEMS IN THE PROCESS OF MITIGATION AND ADAPTATION TO THE EFFECTS OF CLIMATE CHANGE

Forest ecosystems provide a wide range of environmental services with an important role in the Earth’s life-support system. Climate change in Southeastern Europe (SEE) and forecasts for the period until 2070 have a huge impact on the present and future planning in forestry and watershed management, due to the observed trends: the increment of mean annual air temperature from 2,5–5,0 °C until the end of the XXI century; redistribution of annual precipitation, with much more precipitation in the spring-summer period, during short, intensive rain events; a decrease of annual precipitation and soil moisture of 10–20 %, with extreme consequences: dieback and disappearance of forests in huge areas of hilly-mountainous regions. Degradation and loss of forests leads to spread and intensification of soil erosion, with frequent torrential floods, mudflows, landslides, and avalanches. Stable forest ecosystems are pillars of sustainable development, repopulation and could provide means and resources to battle and overcome poverty in moun-tainous regions of southeast Europe.

Effect of marginal topography around the Tibetan Plateau on the evolution of central Asian arid climate: Yunnan–Guizhou and Mongolian Plateaux as examples

Mountains are believed to have played an important role in the evolution of modern arid climate over central Asia. The main topography of the Tibetan Plateau (TP) suppresses the regional atmospheric rainfall by both the modulation of atmospheric circulation and blocking of water vapor transport from the ocean. In this study, the effect of Yunnan–Guizhou and Mongolian Plateaux (YGP and MP, respectively), two marginal topographies around the main TP, on the central Asian aridity are evaluated using general circulation model experiments. The results show that the precipitation over central Asia is significantly decreased by these two topographies. Compared to the whole TP-induced annual precipitation decrease of 0.45 mm/d, the contributions of the YGP and MP reach 0.14 mm/d and 0.08 mm/d, respectively. These two marginal mountains occupy approximately one half of the total change by the TP although they are much smaller in heights and sizes. The orographic forcing of the TP suppresses the precipitation significantly throughout the year while those of YGP and MP are mainly effective in boreal winter. A moisture budget analysis shows that all the mountains examined drive increases in subsidence and resulting decreases in humidity over central Asia, with smaller or opposing roles for changes in horizontal winds. These subsidence changes dominate the drying of Central Asia due to the TP and MP, and are largely driven by the influences of the topography on stationary waves. In contrast, the YGP dries Central Asia primarily through altering transient eddies. The forcing of YGP and MP originate from the mechanical blocking of the tropical easterly and mid-latitude westerly, respectively, which exert significant changes in atmospheric circulation. This implies that the effect of small-scale mountains on arid climate over central Asia might be underestimated and a considerable proportion of mechanical effect of the TP on the Asian aridity actually comes from its margins.

A Multi-Objective Optimization Model for a Non-Traditional Energy System in Beijing under Climate Change Conditions

In recent years, with the increase of annual average temperature and the decrease of annual precipitation in Beijing, the fragility of Beijing’s energy system has become more and more prominent, especially the balance of electricity supply and demand in extreme weather. In the context of unstable supply of new and renewable energies, it is imperative to strengthen the ability of the energy system to adapt to climate change. This study first simulated climate change in Beijing based on regional climate data. At the same time, the Statistical Program for Social Sciences was used to perform multiple linear regression analysis on Beijing’s future power demand and to analyze the impact of climate change on electricity supply in both the RCP4.5 and RCP8.5 (representative concentration pathway 4.5 and 8.5) scenarios. Based on the analysis of the impact of climate change on energy supply, a multi-objective optimization model for new and renewable energy structure adjustment combined with climate change was proposed. The model was then used to predict the optimal power generation of the five energy types under different conditions in 2020. Through comparison of the results, it was found that the development amount and development ratio of various energy forms underwent certain changes. In the case of climate change, the priority development order of new and renewable energies in Beijing was: external electricity > other renewable energy > solar energy > wind energy > biomass energy. The energy structure adjustment program in the context of climate change will contribute to accelerating the development and utilization of new and renewable energies, alleviating the imbalance between power supply and demand and improving energy security.

Climate Change Impact on the Evolution of the Saline Lakes of the Soan-Sakaser Valley (Central Salt Range; Pakistan): Evidences from Hydrochemistry and Water (δD, δ18O) and Chlorine (δ37Cl) Stable Isotopes

The surfaces of saline lakes are shrinking at a threatening rate worldwide. Likewise, the Uchhali complex (formed by three saltwater lakes located in the Salt Range, Pakistan) that serves as a major regional source of water for humans and as a habitat for water birds must be monitored. With this objective in mind, we conducted a study coupling hydrochemistry and stable isotope compositions (δ37Cl, δ18O and δD) in order to characterize its hydrochemical properties and the main processes controlling them. Results showed that the Uchhali complex salinity has dramatically increased compared to other similar lakes in the world. While the Uchhali (UL) and Khabbeki (KL) lakes present a sodium-chloride hydrofacies, the Jahlar (JL) is of a sodium-bicarbonate type. Hydrochemistry parameters indicate that the weathering of surrounding rocks is the major vector for the increase of total dissolved solids in the water. On the other hand, the observed enrichment in heavy isotopes of the water stable isotope compositions implies that the different lakes are undergoing a long history of intense evaporation. The study of the corresponding δ37Cl isotope compositions supports the conclusion that evaporation, along with weathering, are the main driving processes. Besides climate effects that result in the decrease of annual precipitation and the increase of evaporation, water consumption for domestic purposes (household and agriculture) aggravates the rise of the lakes’ salinity.

Projected precipitation changes over the south Asian region for every 0.5 °C increase in global warming

Using all ensemble members of NCAR CCSM4 for historical natural, RCP4.5 and RCP8.5 scenarios from CMIP5, we analyse changes in mean and extreme precipitation over the south Asian region for every 0.5 oC increase in global warming. An increase in mean annual precipitation is projected over majority of the south Asian region with increased levels of warming. Over Indian land, the spatially-averaged annual mean precipitation shows an increase in the range of ~2-14 % based on the RCP scenario and level of warming. However, a decrease in mean annual precipitation is projected over northwest parts of the Indian sub-continent and the equatorial Indian Ocean with increased levels of warming. In general, we find multifold increase in the frequency of occurrence of daily precipitation extremes over the Indian subcontinent and surrounding oceans. Over Indian land, frequency of occurrence of daily precipitation extremes show up to three-fold increase under both RCP scenarios for global warming levels in the range of 1.5 oC–2.5 oC. With further increase in warming we find that the frequency of occurrence of daily precipitation extremes could show a massive four- to six-fold increase over majority of Indian land. Notably, unlike the projected increase in the frequency of occurrence of daily precipitation extremes, the projected change in annual mean precipitation is found to be insignificant in a 1.5 oC warmer world, over majority of the south Asian region, under both RCP scenarios. Given the projected large increase in frequency of daily precipitation extremes with increased levels of warming, our study provides scientific support to the recommendations of the Paris Agreement of 2015.

Predicting hydrologic flows under climate change: The Tâmega Basin as an analog for the Mediterranean region

The potential effects of climate change on the hydrology of the Tâmega River basin, northern Portugal, are assessed by comparing simulated hydrologic scenarios derived from both observational climate databases for a recent past period (1950–2015) and EURO-CORDEX model simulations for the future (2021−2100). Future climate change scenarios are based on an ensemble of five climate model chain experiments and on two Representative Concentration Pathways (RCP4.5 and RCP8.5). Basin-mean annual temperatures are ca. 10% or 20% warmer than in recent past climate (12.4 °C) for RCP4.5 and RCP8.5, respectively. Furthermore, basin-mean annual precipitation decreases by approximately 8% or 13%, when compared to recent past (1255 mm). The Hydrological Simulation Program FORTRAN (HSPF) is applied to the historical data and to each of the five model simulations separately so as to simulate potential changes in flowrates. The model is calibrated and validated using 5 hydrometric stations, achieving satisfactory results regarding flowrate simulation. A reconstruction of flowrates within the entire river basin and over the historical period is accomplished, which is particularly useful when observed data is missing. The projected climate change impacts on annual flowrates reveal a decrease from 18% to 28% relative to observations (70.9 m3 s−1). These findings provide valuable information for the future management and planning of water resources (water security) and can be largely generalized not only to other basins in Portugal, but also over most of Southern Europe and throughout the Mediterranean Basin, where significant warming and drying trends are widespread footprints of climate change.

Combining Use of TRMM and Ground Observations of Annual Precipitations for Meteorological Drought Trends Monitoring in Morocco

The monitoring of drought statewide is a difficult issue especially when the national network of meteorological stations is sparse or do not cover the entire country. In this paper, rainfall satellite estimates derived from Tropical Rainfall Measuring Mission (TRMM) product have been used to evaluate the ability of remote sensing data to study the trends of annual precipitation in Morocco between 1998 and 2012. The standardized precipitation index, SPI, has been chosen to monitor meteorological drought in Morocco. Firstly, the accuracy of TRMM product to estimate annual rainfall was evaluated. Annual precipitations derived from 5113 daily TRMM data were compared to the corresponding rainfall measurements from 23 rain gauges. The results showed a general good linear relationship between TRMM and rain gauges data. When considering annual record, the Pearson correlation coefficient, R², was equal to 0.73 and the root mean square error, RMSE, was equal to 159.8mm/year. The correlation between rain gauge measurements and TRMM rainfall had been clearly improved when working with long-term annual average precipitation. The R² increased to 0.79 and the RMSE decreased to 115,2mm. Secondly, the Mann-kendall tau coefficient, the Theil Sen slope and the contextual Mann-Kendall significance were used to analyze the SPI trends over Morocco. This analysis showed that mainly two regions appeared to be subject of significant trends during the studied period: The extreme north eastern of Morocco manifests a positive SPI trends and is more and more subject of extreme rainfall while the extreme south of the country is suffering from a decrease of annual precipitation which could represent significant socio-economic risks in these areas.

ANN-based statistical downscaling of climatic parameters using decision tree predictor screening method

In this paper, artificial neural network (ANN) was used for statistically downscale the outputs of general circulation models (GCMs) to assess future changes of precipitation and mean temperature in Tabriz synoptic station at north-west of Iran. Since one of the significant subjects in statistical downscaling of GCMs is to select the most dominant large scale climate variables (predictors) among huge number of potential predictors, the predictors screening methods including decision tree, mutual information (MI) and correlation coefficient (CC) were used to statistically downscale mean monthly precipitation and temperature. Three GCMs were used, including Can-ESM2 and BNU-ESM from IPCC AR5 models and CGCM3 from IPCC AR4 models. The results of downscaling in the base period (1951–2000) indicated that among feature extraction methods decision tree had superiority to MI and CC techniques. Therefore, the future projection of precipitation and mean temperature during 2020–2060 was implemented using ANN-based simulation according to the most efficient downscaling model (i.e., decision tree-based calibration). Different results according to different GCMs and scenarios were obtained for precipitation projection. In this way, the Can-ESM2 model under RCP8.5 showed 29.78% decrease in annual precipitation and CGCM3 model under B1 indicated 1.06% increase of annual precipitation. Temperature projection outcomes denoted that annual mean temperature will increase over the region and the most increase in mean temperature was determined by BNU-ESM model under RCP8.5.

THE IMPACT OF CLIMATE VARIABILITY ON DROUGHT MANAGEMENT: EVIDENCE FROM JAPANESE RIVER BASINS

This study examines the effect of climate variability on water resource management during droughts. We use data from local droughts in Japan over three decades to investigate how variability in precipitation and temperature affects water restrictions implemented by drought coordination councils. We find that climate variability is significantly related to water restrictions in terms of both intensity and duration. The regression results show that a 100-mm decrease in annual precipitation is associated with a 0.2% increase in the water withdrawal restriction rate and an increase of one day in the restriction period. Our findings suggest that climate variability might induce more stringent water restrictions, implying negative consequences for water availability. This study thus shows the importance of strategically building adaptive capacity to climate change due to the risks of extreme weather events, such as prolonged droughts and extended summer seasons.

A multi-model analysis of glacier equilibrium line altitudes in western China during the last glacial maximum

Based on numerical experiments undertaken with nine climate models, the glacier equilibrium line altitudes (ELAs) in western China during the last glacial maximum (LGM) are investigated to deepen our understanding of the surface environment on the Tibetan Plateau. Relative to the preindustrial period, the summer surface air temperatures decrease by 4–8°C while the annual precipitation decreases by an average of 25% across the Tibetan Plateau during the LGM. Under the joint effects of reductions in summer temperature and annual precipitation, the LGM ELAs in western China are lowered by magnitudes that vary with regions. The ELAs in the southern margin and northwestern Tibetan Plateau decline by approximately 1100 m; the central hinterland, by 650–800 m; and the eastern part, by 550–800 m, with a downward trend from southwest to northeast. The reduction in ELAs is no more than 650 m in the Tian Shan Mountains within China and approximately 500–600 m in the Qilian Mountains and Altai Mountains. The high-resolution models to reproduce the low values of no more than 500 m in ELA reductions in the central Tibetan Plateau, which are consistent with the proxy records from glacier remains. The accumulation zones of the Tibetan Plateau glaciers are mainly located in the marginal mountains during the LGM and have areas 2–5 times larger than those of the modern glaciers but still do not reach the central part.

Modeling climate change impacts on precipitation in arid regions of Pakistan: a non-local model output statistics downscaling approach

The uncertainties in climate projections in arid regions are quite high due to the large variability of climate and the lack of high-quality climate observations. In this study, an ensemble of four Coupled Model Intercomparison Project Phase 5 (CMIP5) General Circulation Model (GCM) namely GISS-E2-H, HadGEM2-ES, MIROC5, and NorESM1-M simulations was downscaled for the assessment of the spatiotemporal changes in precipitation in the data-scarce arid province (Balochistan) of Pakistan for four Representative Concentration Pathway (RCP) scenarios. The gauge-based gridded precipitation data of the Global Precipitation Climatology Centre (GPCC) having a spatial resolution of 0.5° was used for this purpose. Support Vector Machine (SVM) was used for the development of non-local model output statistics (MOS) downscaling models for each grid by linking the GPCC precipitation with the GCM simulated precipitation across a spatial domain (latitudes 03°–45° N and longitudes 42°–92° E). Then, Random Forest (RF) algorithm was used to develop the multi-model ensemble (MME) of downscaled precipitation projections. The performances of the models were assessed in terms of normalized root mean square error (NRMSE), percentage of bias (PBIAS), and modified index of agreement (md). The results indicated that the non-local SVM-based MOS models coupled with RF MME can simulate historical precipitation over the region quite well. The MME of GCMs projected changes in the annual, monsoon, and winter precipitation in the range of − 30% to 30% for different RCPs. Overall, the MME of GCMs indicated an increase in precipitation in the monsoon-dominated wetter regions in the east, while a decrease in winter precipitation dominated arid region in the west. A decrease in annual precipitation over the majority of the southeast, east, and northeastern arid regions was projected which may increase the aridity in the region.