Long-term Changes In Precipitation Research Articles

Increase in precipitation will facilitate the ecological stability of desert steppe in the future

Community stability plays a vital role in ensuring the consistent provision of ecosystem services despite climatic changes. It is presumed that future changes to annual precipitation will impact the ecological stability of many systems, particularly the ‘fragile’ desert steppe. However, most studies of ecological stability are inferred from short-term field precipitation manipulation experiments. There is still extensively to learn regarding how the desert steppe reacts to long-term changes in precipitation. We conducted a 7-year experimental study monitoring the aboveground biomass of major plant functional groups (perennial grasses, perennial forbs, annual herbs, and semi-shrubs) under four experimentally manipulated precipitation gradients [reducing natural precipitation by 50% (-50%), natural precipitation (CK), increasing natural precipitation by 50% (+50%), and increasing natural precipitation by 100% (+100%)] to evaluate how changes in precipitation affect the biomass stability of plant communities. We did observe higher levels of species asynchrony, resistance, resilience, and temporal stability of community and functional groups in experimental plots receiving more precipitation. Interestingly, the contribution of species richness to community stability was not observed in our experiment. The increase in soil water content in the 20–30 cm soil layer caused by increased precipitation promoted the resilience of perennial grasses but inhibited the resistance of perennial forbs. At the same time, the decrease in soil inorganic nitrogen caused by increased rainfall inhibited the resilience of perennial grasses. Notably, community resilience predominantly hinged on the resilience of perennial grasses, while community resistance was primarily dictated by the resistance of perennial forbs. Moreover, species asynchrony emerged as the primary regulator of community temporal stability. Our long-term experimental evidence underscores the transformative potential of precipitation in reshaping grassland stability across both functional and structural dimensions. Importantly, sustaining the high stability of perennial herbs emerges as a strategic avenue for enhancing the ecological stability of the desert steppe in the face of evolving precipitation patterns.

Late Holocene climate dynamics in the Azores archipelago

The location of the Azores Archipelago makes this group of islands an excellent setting for investigating past long-term temperature and precipitation changes in the central North Atlantic region. Here, we present a chironomid-based quantitative temperature reconstruction and a record of oxygen isotope composition of chironomid head capsules for the last ca. 1200 years, based on the Lake Prata core (São Miguel Island, Azores). Chironomids from Lake Prata show that the temperature trend is aligned with the prevailing past global temperature trends, indicating warming during the Medieval Climate Anomaly (MCA; ca. 950–1300 CE) and subsequent cooling during the Little Ice Age (LIA; ca. 1300–1800 CE). Furthermore, changes in lake water oxygen isotope composition from chironomid head capsules were recorded with more positive δ18O values (18.2 ± 0.2‰) during the MCA and more negative values (varying between 14.8‰ and 17.6‰) during the LIA, indicating a positive shift in the precipitation-evaporation balance and/or heavier precipitation in winter relative to summer. Our study revealed that, in subtropical regions with a temperate oceanic climate and low thermal variation, there is a limited correlation between the isotopic composition of precipitation and temperature. Additionally, the temporal sequence of oxygen isotope values obtained from chironomid head capsules closely corresponds to variations in precipitation seasonality inferred from distinct climatic proxies. This consistency underscores the robustness of quantitative reconstructions and indicates that δ18Ochironomid records are promising for future investigations, especially in the context of lakes located on oceanic islands characterised by limited thermal variability.

Understanding climate change dynamics in the Godavari middle sub-basin using parametric and non-parametric models

Climate change is considered a long-term change in precipitation, temperature and other meteorological variables. The pattern of meteorological variables is changing due to anthropogenic activities globally. Climate change has posed threat to natural and human systems. Thus, assessing and forecasting climate variability have become imperative for making resources sustainable and society resilient. This study examined trend and forecasted climate change using parametric and non-parametric methods in the Godavari Middle Sub-basin, India. Mann-Kendall and Sen's slope methods were utilized to analyze trend and magnitude of meteorological variables such as rainfall, maximum and minimum temperature, mean wind speed, mean evaporation and relative humidity. Forecasting of meteorological variables was carried out using the autoregressive integrated moving average (ARIMA) and seasonal autoregressive integrated moving average (SARIMA) models. Increasing trend in maximum and minimum temperature was observed at various level of significance. Decreasing trend was observed in mean evaporation at 0.05 level of significance. Decreasing trend in wind speed was also recorded in the sub-basin. February, March, April, June, October and December have shown increasing trend in relative humidity. Total monthly rainfall has shown decreasing trend in the south-eastern part of the sub-basin. Forecast of meteorological variables have also shown decrease in rainfall, increase in maximum and minimum temperature during 2017–2027 creating the sub-basin more prone to dry climate condition. Thus, a policy intervention-oriented climate action plan for lessening the impact of climate change is required in the sub-basin.

Perceptions of environmental changes among a climate-vulnerable population from Bangladesh

Effective climate change adaptation requires a thorough understanding of whether and how affected populations perceive climatic and environmental changes. Existing research has been inconclusive regarding the consistency of these perceptions compared to objective meteorological indicators. Moreover, no systematic comparison has been done for the perception of discrete environmental events such as floods or erosion. This study relies on novel panel survey data of approximately 1700 households residing along the Jamuna River in Bangladesh as well as on unique individual-level, satellite-based erosion data. It compares respondents’ perceptions of environmental events, namely riverbank erosion, and three climate change indicators, specifically long-term temperature change and changes in precipitation during wet and dry seasons, to objective measurements using satellite imagery and climatic time-series data (CRU TS). I find that long-term temperature change is perceived more accurately than long-term changes in precipitation. Given that educational attainment and climate change literacy among the study population are low, this indicates that global temperature increases are felt even by remote populations who have never heard the term climate change. Erosion is strongly overestimated, especially by those respondents who had been personally affected by it. Since human behavior is guided by perceptions rather than objective data, this has important policy implications, underlining the importance of considering people’s perceptions if the goal is to assist them in adapting to environmental changes.

Long-term changes in temperature, specific humidity, and precipitation in Bangladesh revealed by ERA5 data

Long-term changes in temperature, specific humidity, and precipitation in Bangladesh revealed by ERA5 data

Population dynamics in Taiwan from the Neolithic to early historic periods (5000–100 cal BP): Linking cultural developments and environmental change

To reconstruct population dynamics in Taiwan between 5000 and 100 cal BP, we analysed spatial-temporal changes in archaeological site abundance and size (area). The results suggest that population growth was discontinuous throughout the study region and that the main spatial differences in population trends were between eastern/northern and western Taiwan. Comparison of settlement data shows that population trends in Taiwan and different regions in continental China were partly parallel. We contrast these data with political, economic, settlement, and climatic developments in continental China, when considering possible factors that influenced these demographic relationships. In addition, we examined published palaeoenvironmental time series from the broader study region to explore human-environment interactions. This revealed that proxy records of human activities (agriculture, deforestation) correlate with the derived trends in site abundance and area. Furthermore, we hypothesise that the inferred sparse settlement in eastern Taiwan during 2700–1800 cal BP is related to climate change. An increase in seasonal rainfall and high-intensity precipitation events in late summer and autumn, due to long-term changes in summer monsoon precipitation and El Niño–Southern Oscillation intensity, likely resulted in unfavourable hydrological conditions for crop cultivation in this part of the study region.

Validation of high-resolution satellite precipitation products over West Africa for rainfall monitoring and early warning

Satellite rainfall estimation products (SRPs) can help overcome the absence of rain gauge data to monitor rainfall-related risks and provide early warning. However, SRPs can be subject to several sources of errors and need to be validated before specific uses. In this study, a comprehensive validation of nine high spatial resolution SRPs (less than 10 km) was performed on monthly and dekadal time scales for the period 2001–2015 in West Africa. Both SRPs and reference data were remapped to a spatial resolution of 0.1 ° and the validation process was carried out on a grid scale, with 1,202 grids having at least one rain gauge throughout West Africa. Unconditional statistical metrics, such as mean absolute error, Pearson correlation, Kling-Gupta efficiency and relative bias, as well as the reproducibility of rainfall seasonality, were used to describe the agreement between SRPs and reference data. The PROMETHEE II multi-criteria decision analysis (MCDA) method was employed to rank SRPs by considering criteria encompassing both their intrinsic characteristics and performance metrics. Overall, IMERGv6-Final, MSWEPv2.2, RFE2, ARC2, and TAMSATv3.1, performed reasonably well, regardless of West African climate zones and rainy season period. Given the performances displayed by each of these SRPs, RFE2, ARC2, and MSWEPv2.2 would be suitable for drought monitoring. TAMSATv3.1, IMERGv6-Final, RFE2, ARC2, and MSWEPv2.2 are recommended for comprehensive basin water resources assessments. TAMSATv3.1 and MSWEPv2.2 would be of interest for the characterization of variability and long-term changes in precipitation. Finally, TAMSATv3.1, ARC2, and MSWEPv2.2, could be good alternatives to observed data as predictants in West African Regional Climate Outlook Forum (RCOF) process.

Analysis of the driving factors of precipitation change during the development of the Jing-Jin-Ji urban agglomeration

Urbanization has an important impact on local precipitation changes. Previous studies of urban precipitation have largely considered single precipitation events, with few long-term statistical studies based on multiple samples. Therefore, based on WRF model simulations, this study extracted the latent heat flux, sensible heat flux, net radiation, friction velocity, albedo, and precipitation of 156 urban units in Beijing-Tianjin-Hebei (Jing-Jin-Ji) urban agglomeration for the summers of 2001–2019, and identified the main factors driving long-term urban precipitation changes based on multiple samples. There were three key results. 1) The factors that had the greatest impact on urban precipitation changes in Jing-Jin-Ji were the sensible heat flux, latent heat flux, and friction velocity. The latent heat flux was the leading factor driving precipitation changes during the urbanization of Jing-Jin-Ji. 2) In the different stages of urbanization, there were different factors affecting urban precipitation changes. In highly urbanized cities, the sensible heat flux had the greatest impact on precipitation changes, followed by the friction velocity. For medium-sized cities, the friction velocity was the most important variable. For small cities, the latent heat flux was the most important factor. 3) The friction velocity was the leading factor in precipitation change at the 0.95 quantile in Jing-Jin-Ji, and was therefore the most important factor driving changes in urban extreme precipitation. The results provide a theoretical basis for the formulation of climate policies, and disaster prevention and mitigation in Jing-Jin-Ji. They will also assist in promoting the construction of an ecological civilization and building safe and livable cities.

Climate Variability and Trends in Imotski, Croatia: An Analysis of Temperature and Precipitation

This paper examines the long-term changes in temperature and precipitation in the karst region of Imotski, Croatia, which is of particular interest due to its abundance of karst phenomena. This study analyses temperatures and precipitation on monthly and annual scales at two climatological stations in the region, Imotski and Ričice. Linear regression, the Theil–Sen estimator (β), and the Mann–Kendall test were used to determine the trends and statistical significance. The homogeneity of the data was checked using the Standard Normal Homogeneity Test (SNHT), and the F-test and t-test were used to test the significance of the mean shift between the two subseries. Additionally, the coefficient of variability, standardized rainfall anomaly, and precipitation concentration index were employed to analyze the precipitation variability. The study found a statistically significant (p < 0.05) upward trend in the mean (β = 0.0437) and maximum (β = 0.0590) annual air temperature at the Imotski station and the mean (β = 0.0387) annual temperature at the Ričice station. The SNHT test showed a statistically significant (p < 0.05) shift in the mean annual temperatures after 2007 and maximum annual temperatures after 1998 at the Imotski station. Similarly, a statistically significant (p < 0.05) shift in the mean annual temperatures after 2011 and the maximum annual temperatures after 1998 was found at the Ričice station. A seasonal distribution of precipitation is observed at both the Ričice and Imotski stations, with a downward trend (β = −2.7693) at Ričice and an upward trend (β = 6.0575) at Imotski; however, neither trend is statistically significant (p > 0.05). An increase in the intensity of dry periods and the occurrence of extreme events was also noted. The climatological analysis, conducted for the first time in this area, is a crucial step toward understanding local climate patterns and making informed decisions toward sustainable development and adaptation strategies.

Understanding physical climate risks and their implication for community adaptation in the borana zone of southern Ethiopia using mixed-methods research

Pastoralists in the Borana zone of southern Ethiopia are grappling with climatic risks and impacts, and their livelihoods appear to be precarious. The long-term changes in precipitation, temperature and extreme events are under-researched aspects of climate risk in the study area. Climate observations, local people’s experiences, and memories of weather and drought patterns were analysed in this work to better understand the climate risks in the study region and provide actionable knowledge to facilitate adaptations. In southern Ethiopia, the primary drivers of climate risks are rainfall variabilities, rising temperatures, and drought. The annual rainfall variability observed in the study area (20–35%) is greater than the overall estimate for Eastern Africa (15–25%), indicative of a heightened climate risk in this area. Furthermore, seasonal and intra-seasonal rainfall variabilities are being aggravated by rising temperatures, leading to increased frequency and magnitude of extreme events, particularly in the lowland area. These changes, specifically droughts of different intensities occurring every 2–3 years, erode the livelihood of the pastoralists. The lack of consensus among stakeholders as to the causes and aggravating factors of these climate changes impedes adaptation actions. The authors recommend the importance of initiating a participatory platform that will facilitate discussion on climate change to create a common understanding of the problem and relate it to public policy. The use of gridded precipitation and temperature data is recommended in future research to improve the availability of climate information for climate risk management. In addition, the use of mixed methods and local knowledge, as demonstrated in this study, is highly recommended to better understand climate risks, particularly when there is a limited availability and quality of long-time-series climate data.

Long-Term Precipitation Changes in the Baiu and Akisame Seasons in Japan over the Past 120 Years (1901–2020)

Long-Term Precipitation Changes in the Baiu and Akisame Seasons in Japan over the Past 120 Years (1901–2020)

Mg records of two stalagmites from B7-Cave (northwest Germany) indicating long-term precipitation changes during Early to Mid-Holocene

Two stalagmites from B7-Cave in northwest Germany, which is part of the same cave system as the intensively studied Bunker Cave, were re-dated by multi collector inductively coupled plasma mass spectrometry (MC-ICPMS) 230Th/U-dating. Furthermore, the concentration of Mg, Sr, Ba, P, Y, Zn, and Al were determined at high-resolution by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Stalagmite B7-1 grew from 10.8 to 5.8 ka BP. Stalagmite B7-7 grew during three growth phases from 11.0 to 6.2, 3.13 to 2.86 (late Bronze Age), and 1.27 to 1.15 ka BP (early Medieval Period). Aluminium is a proxy for detrital material and corresponds very well with the visible detrital layers in stalagmite B7-1 and the oldest growth phase of stalagmite B7-7. The two younger growth phases of stalagmite B7-7 are very clean and show very low Al concentrations. Phosphorus, Y, and Zn show positive correlations in both stalagmites and all growth phases, but do not show a relationship to temperature or precipitation. This may be related to the elevated detrital content in both stalagmites. Barium and Sr also show a positive correlation in both stalagmites and all growth phases, which is related to their dependency on growth rate. Magnesium is most probably influenced by prior calcite precipitation and therefore a proxy for past precipitation/infiltration. The Mg records of stalagmite B7-1 and of the oldest growth phase of stalagmite B7-7 show decreasing Mg concentration with time reflecting decreasing prior calcite precipitation and therefore increasing precipitation during the Early to Mid-Holocene. This is consistent with other climate reconstructions from Central Europe.

Extreme precipitation changes over the Yangtze River Basin in 1901-2020

To better understand the characteristics of long-term change and variability in regional extreme precipitation and to examine possible regional responses to global climate warming, we analyzed temporal and spatial patterns of precipitation and extreme precipitation index changes in the Yangtze River Basin (YRB) over the last 120 yr. Based on the China Meteorological Administration’s daily precipitation data set of 60 city stations in mainland China from 1901-2020, we found that total annual precipitation and daily precipitation intensity of the Upper Reaches (UR) experienced a downward trend, but those of the Middle and Lower Reaches (MLR) showed an upward trend. Precipitation amount and intensity increased, while the number of precipitation days slightly decreased over the YRB during 1901-2020. Most extreme precipitation indices showed a decreasing trend in the first 60 yr that reversed after 1961 into slightly upward trends, except for consecutive dry days and wet days in the YRB during 1901-2020. There were significant downward trends for consecutive dry days and maximum 1 and 5 d precipitation during the first 60 yr, and significant upward trends for maximum 1 d precipitation, total extreme heavy precipitation, and very heavy precipitation days in the last 60 yr. The trends for extreme precipitation in the UR were lower than those in the MLR during 1901-2020, particularly in the last 60 yr, whereas the trends in the UR were higher than those in the MLR during 1901-1960. The fluctuations of extreme precipitation indices in the UR were more dramatic than those in the MLR, and the extreme precipitation indices all showed 5-10 or 20 yr periodic variabilities. The analysis also showed that observed changes in regional extreme events were directly related to rapid urbanization around the stations and multi-decadal variability of the East Asian monsoon.

Fine root biomass of European beech trees in different soil layers show different responses to season, climate, and soil nutrients

Fine roots are crucial for water and nutrient acquisition in plants; yet it is unknown how nutrient inputs and soil fertility in forests influence fine root biomass seasonal trajectories. Here, we hypothesized that standing fine root biomass increases with addition of a limited resource and shows different seasonal patterns depending on nutrient availability and phenology. We further hypothesized that the influence of climate is greater in the organic layer, causing larger responses of root biomass to climate in the organic layer and stronger responses to nutrient changes in mineral soil. We conducted our study in three European beech (Fagus sylvatica) forests representing a soil fertility gradient with high, medium, and low phosphorus (P) contents. A fully factorial fertilization regime with N and P was applied at each forest site. To test our hypotheses, we conducted soil coring in spring and fall for 2.5 years. Soil cores were fractionated into organic layer (Oe + Oa layer) and mineral soil (A horizon) and used to determine fine root biomass, soil pH and moisture, total concentrations of soil and root nutrients (basic cations, micronutrients, S, P, N, C), soluble concentrations of soil and root P. Fine root biomass in the mineral soil at the forest site with the lowest soil P content increased in response to P addition. Pheno-seasonal changes caused increases in soil P and N in spring and opposing cycling of biomass and fine root labile P contents at the P-medium and P-high sites. Contrary to our expectation, we observed stronger climatic effects on fine root biomass in the mineral soil, whereas soil moisture was more important in explaining fine root biomass variation in the organic layer. Our results show that seasonal patterns of fine root biomass are dependent on the stratification of environmental factors with soil depth and imply negative consequences for fine root biomass in the organic soil layer due to acute soil water content fluctuations and climate change effects in the mineral horizon due to long-term precipitation changes.

Holocene precipitation changes in the Balikun basin based on high-resolution sporopollen quantitative reconstruction

To better understand long-term precipitation changes in arid Central Asia, reconstruction of past precipitation is critical. This paper analyzed the core sediments of Balikun lake in eastern Xinjiang. We analyzed 200 pollen samples, combined with 441 surface pollen samples and a radiocarbon chronology, using the Weighted Averaging Partial Least Sequence (WA-PLS) method, to characterize the Holocene high-resolution precipitation change process in Balikun basin. And, Combined with the vegetation types reconstructed by biome method, we discussed the landscape evolution of Balikun basin. Results show that the mean annual precipitation during the Holocene can be broken into three phases: Early Holocene (11,750–8030 cal yr B.P.), which averaged about 130 mm; Middle Holocene (8030–4420 cal yr B.P.), which averaged about 250 mm; and Late Holocene (4420–0 cal yr B.P.), which averaged about 210 mm. The vegetation changed from desert to steppe during the Holocene, and the wetlands gradually expanded, which was mainly informed by precipitation and glacial melt water.

Impact of the long-term precipitation and land use changes on runoff variations in a humid subtropical river basin of China

Study regionLiuxihe River Basin in Guangdong province, China. Study focusDeciphering the runoff variation and its causes is crucial for catchment water management. The impacts of long-term precipitation aand land use change on the annual surface runoff were quantitatively analysed using various methods for the period of 1948–2019. New hydrological insightsWe found that abrupt change occurred in 2009 for precipitation and 2003 for runoff, and the slope of precipitation-runoff cumulative curve changed after 2000 with an increase of ~122 %. This indicated that human activities in the early 2000 s may have resulted in a marked increase of runoff in addition to precipitation. The dominant land use transfer was from croplands to constructed lands, most profoundly during 2000–2010. The multiple linear regression analysis indicated that the increase of precipitation and the cropland-to-constructed land transitions were nearly equally responsible for the runoff increase. In total, the long-term precipitation and major land use change explained ~79 % of annual runoff variation. Furthermore, the effect of surface water area especially the pond area was discussed, and the negative linear relationship was found not statistically significant, but the impact of pond area ratio and its storage capacity on peak flow during rainstorms is worth further exploration towards flood mitigation, which can serve as an important and effective measure for nature-based management.

Multiple satellite-observed long-term changes in the summer diurnal precipitation over Luzon and its adjacent seas during 2000–2019

• Change in summer diurnal rainfall in Luzon and nearby seas since 2000 was examined. • The robustness features were identified based on satellite precipitation products. • The diurnal rainfall in most of Luzon declined from 2000–2009 to 2010–2019. • Propagation of diurnal rainfall from western Luzon to South China Sea has enhanced. • Causes of diurnal rainfall changes were linked to atmospheric circulation changes. Long-term satellite precipitation products (SPPs) provide insight into how precipitation has changed in the past. As the changes observed from various SPPs may differ, research is needed to clarify related uncertainties using multiple SPPs. This study aims to explore long-term changes in the summer (June to August) diurnal precipitation over Luzon and its adjacent seas using multiple SPPs from 2000 − 2019, and to determine the possible atmospheric thermodynamic causes of such changes using the latest atmospheric reanalysis data. The four SPPs include the TRMM 3B42, the IMERG Final Run, the PERSIANN-CDR, and the PERSIANN-CCS-CDR. Our results show that all four SPPs depicted a common diurnal precipitation signal formed over the coastal region of western Luzon propagating westward to the adjacent South China Sea (SCS). This feature had been enhanced from 2000–2009 (Period1) to 2010–2019 (Period2). By contrast, there was uncertainty for central to eastern Luzon, where most SPPs with the exception of PERSIANN-CCS-CDR, captured a decline in diurnal precipitation from Period1 to Period2. These long-term changes in diurnal precipitation, which were suggested by the majority of SPPs, were further attributed to a strengthening (weakening) of local diurnal heating and related wind convergence over the SCS (Luzon), coupled with an intensification of regional prevailing winds. These findings highlight how the formation of precipitation over Luzon and SCS has changed under a changing climate.

Global Mangrove Deforestation and Its Interacting Social-Ecological Drivers: A Systematic Review and Synthesis

Globally, mangrove forests are substantially declining, and a globally synthesized database containing the drivers of deforestation and drivers’ interactions is scarce. Here, we synthesized the key social-ecological drivers of global mangrove deforestation by reviewing about two hundred published scientific studies over the last four decades (from 1980 to 2021). Our focus was on both natural and anthropogenic drivers with their gradual and abrupt impacts and on their geographic coverage of effects, and how these drivers interact. We also summarized the patterns of global mangrove coverage decline between 1990 and 2020 and identified the threatened mangrove species. Our consolidated studies reported an 8600 km2 decline in the global mangrove coverage between 1990 and 2020, with the highest decline occurring in South and Southeast Asia (3870 km2). We could identify 11 threatened mangrove species, two of which are critically endangered (Sonneratia griffithii and Bruguiera hainseii). Our reviewed studies pointed to aquaculture and agriculture as the predominant driver of global mangrove deforestation though their impacts varied across global regions. Gradual climate variations, i.e., sea-level rise, long-term precipitation, and temperature changes and driven coastline erosion, salinity intrusion and acidity at coasts, constitute the second major group of drivers. Our findings underline a strong interaction across natural and anthropogenic drivers, with the strongest interaction between the driver groups aquaculture and agriculture and industrialization and pollution. Our results suggest prioritizing globally coordinated empirical studies linking drivers and mangrove deforestation and global development of policies for mangrove conservation.

Multiple trend tests on air temperature and precipitation anomalies in Vietnam

Abstract An informed decision on building climate resilience and adaptation requires a deep understanding of long-term changes in temperature and precipitation, especially for most vulnerable countries to climate extremes like Vietnam. Hence, this study aimed to comprehend spatiotemporal trend possibilities of temperature and precipitation in Vietnam by employing multiple non-parametric statistical trend tests. This study also suggested a modified procedure, represented as a Hovmöller-like diagram, for enhancing the characterization of long-term spatiotemporal trends by applying multiple monotonic trend tests to all latitude coordinates through all possible 30-year periods. The superiority of multiple trend tests over a single one is that this methodology can assess the sensitivity of trend test results to the beginning years, ending years, and record lengths, thus emphasizing the necessity of performing monotonic trend tests repeatedly. The results show consistent warming trends in all climate sub-regions over the last 4–5 decades, with the estimated trend slopes varying from approximately 0.010–0.042 °C/year. Precipitation anomalies in most climate sub-regions, especially in the southern part, experienced significant increasing trends at the rate of around 0.29–2.76%/year during the last 3–5 decades. These findings are expected to contribute more insights into the spatiotemporal trend patterns of temperature and precipitation in Vietnam.

Plausible Precipitation Trends over the Large River Basins of Pakistan in Twenty First Century

Inter alia, inter-annual and spatial variability of climate, particularly rainfall, shall trigger frequent floods and droughts in Pakistan. Subsequently, a higher proportion of the country’s population will be exposed to water-related challenges. This study analyzes and projects the long-term spatio-temporal changes in precipitation using the data from 2005 to 2099 across two large river basins of Pakistan. The plausible precipitation data to detect the projected trends seems inevitable to study the future water resources in the region. For, policy decisions taken in the wake of such studies can be instrumental in mitigating climate change impacts and shape water management strategies. Outputs of the Coupled Model Intercomparison Project 5 (CMIP5) climate models for the two forcing scenarios of RCP 4.5 and RCP 8.5 have been used for the synthesis of projected precipitation data. The projected precipitation data have been synthesized in three steps (1) dividing the area in different climate zones based on the similar precipitation statistics (2) selection of climate models in each climate zone in a way to shrink the ensemble to a few representative members, conserving the model spread and accounting for model similarity in a baseline period of 1971–2004 and the projected period of 2005–2099 and (3) combining the selected model’s data in mean and median combinations. The future precipitation trends were detected and quantified, for the set of four scenarios. The spatial distribution of the precipitation trends was mapped for better understanding. All the scenarios produced consistent increasing or decreasing trends. Significant declining trends were projected in the warm wet season at 0.05% significance level and the increasing trends were projected in cold dry, cold wet and warm dry seasons. Framework developed to project climate change trends during the study can be replicated for any other area. The study therefore can be of interest for researchers working on climate impact modeling.