Increase In Annual Precipitation Research Articles

Spatio-Temporal Trends in Precipitation, Temperature, and Extremes: A Study of Malawi and Zambia (1981–2021)

Analyzing long-term climate changes is a prerequisite for identifying hotspot areas and developing site-specific adaptation measures. The current study focuses on assessing changes in precipitation, maximum and minimum temperatures, and potential evapotranspiration in Zambia and Malawi from 1981 to 2021. High-resolution precipitation and temperature datasets are used, namely, Climate Hazards Group InfraRed Precipitation with Station data (0.05°) and Multi-Source Weather (0.1°). The Mann–Kendall trend test and Sen’s Slope methods are employed to assess the changes. The trend analysis shows a non-significant increase in annual precipitation in many parts of Zambia and Central Malawi. In Zambia and Malawi, the average annual and seasonal maximum and minimum temperatures show a statistically significant increasing trend (up to 0.6 °C/decade). The change in precipitation during the major rainy seasons (December–April) shows a non-significant increasing trend (up to 3 mm/year) in a large part of Zambia and Central Malawi. However, Malawi and Northern Zambia show a non-significant decreasing trend (up to −5 mm/year). The change in December–April precipitation significantly correlates with El Niño–Southern Oscillation (Indian Ocean Dipole) in Southern (Northern) Zambia and Malawi. To minimize the impact of the observed changes, it is imperative to develop adaptation measures to foster sustainability in the region.

The future of droughts in Iran according to CMIP6 projections

Anthropogenic climate change is exerting immense pressure on water resources in Iran. This study investigates future precipitation and meteorological droughts across the country considering performances of 41 General Circulation Models (GCMs). The findings indicate a significant increase in Long-term Average Annual Precipitation (LAAP) across Iran with an overall north-to-south increasing gradient, particularly in areas prone to extreme events. However, focusing solely on LAAP is misleading. Projected precipitation reveals substantial inter-annual variability, impacting both the severity and duration of meteorological droughts. For instance, 100-year return period droughts are expected to intensify in severity (SSP1-2.6: 4-91%, SSP8-5.5: 46-204%) and duration (SSP1-2.6: 19-76%, SSP8-5.5: 40-127%) across most regions, except the Persian Gulf coastal zone, where droughts may become less severe (SSP1-2.6: 23%, SSP8-5.5: 23%) and shorter in duration (SSP1-2.6: 27%, SSP8-5.5: 10%). Additionally, bivariate frequency analysis suggests that major droughts could become significantly more frequent in the future.

Precipitation Changes on the Northern Slope of the Kunlun Mountains in the Past 42 Years

The precipitation on the northern slope of the Kunlun Mountains significantly impacts the green economy of the Tarim Basin’s southern edge. Observations have noted an expansion of the surface water area in this region, though the reasons for this are not yet fully understood. Due to limited instrumental data, this study leverages field measurements from the third Xinjiang comprehensive expedition and multiple gridded datasets. Through trend analysis and a geographical detector model, it examines the precipitation’s decadal, interannual, and seasonal variations across key areas (Hotan River Basin, Keriya River Basin, Qarqan River Basin, and Kumukuli Basin), identifying factors behind the spatial and temporal distribution of regional precipitation. The findings reveal the following: (1) An increase in annual precipitation across the region from 187.41 mm in the 1980s to 221.23 mm in the early 21st century, at a rate of 10.21 mm/decade, with the most significant rise in the eastern Kunlun-Kumukuli Basin. (2) Precipitation exhibits clear seasonal and spatial patterns, predominantly occurring in spring and summer, accounting for 90.27% of the annual total, with a general decrease from the mountains towards downstream areas. (3) Rising average annual temperatures contribute to an unstable atmospheric structure and increased water-holding capacity, facilitating precipitation. Significant influences on precipitation changes include the North Atlantic Oscillation and solar flux, explaining 43.98% and 31.21% of the variation, respectively.

Climate-Driven Changes in Annual Flow Patterns: A Comprehensive Analysis of the Buktyrma River (Kazakhstan)

This article examines and calculates the annual flows of rivers in the Buktyrma River basin in connection with changing climatic conditions affecting runoff formation. An analysis of climatic characteristics, based on data from meteorological stations of the hydrometeorological service of Kazakhstan, indicates intense warming and a moderate increase in annual precipitation since the early 1980s. The more intense melting of high-mountain snow and glaciers has led to a reduction in glaciated areas. Alongside the noted trend of increasing precipitation, this melting contributes to an increase in surface runoff. According to Global Land Ice Measurements from Space data, there has been a reduction in the area of glaciers in the river basin and a complete disappearance of glaciers in the Sarymsakty River basin. Studying long-term water-flow data in the basin has helped identify periods with consistent patterns. These periods are characterized by different values of probability-distribution-curve parameters. An assessment of the homogeneity of the identified periods of runoff series over the past decades, using known parametric criteria, confirmed the reliability of the calculated values of annual runoff. The observed increase in the norm, depending on elevation, glacier presence, and the spatial orientation of watershed ridges, ranges from 5% to 52%. The observed trends in changes in climatic characteristics and runoff indicators of the rivers in the basin support water-management planning in this region. This includes using the approximation of empirical river-supply curves, which can aid in assessing the calculated hydrological characteristics.

Effects of soil water content at freezing, thaw temperature, and snowmelt infiltration on N2O emissions and denitrifier gene and transcript abundance during a single freeze-thaw event

Climate change-related warming and increased precipitation may alter winter snow cover and thawing events, and therefore, may carry significant consequences for nitrous oxide (N2O) production pathways such as denitrification, and the abundance and expression of denitrifying microorganisms. We used a soil microcosm study to investigate the combined effect of soil thaw temperature, initial water filled pore space (WFPS) prior to soil freezing, and snowmelt infiltration simulated by the addition of water on N2O emission and denitrification rates, soil respiration rate, and the abundance and transcription of denitrifying (nirK, nirS, and nosZ) bacteria during a single freeze-thaw event. Soil respiration rate was primarily controlled by an increase in soil thaw temperature, whereas soil N2O emission and denitrification rates were generally greater in soils with a higher initial WFPS and soil thaw temperature. In contrast, snowmelt infiltration generally had a negligible effect on these rates, which may be related to pre-existing soil conditions that were already conducive to denitrification. Unexpectedly, the nosZ transcript/nosZ gene abundance ratio was lower in soils thawed at 8.0 °C compared to 1.5 °C; however, this may have resulted in a lower N2O reduction, thus explaining the greater levels of N2O emitted from soils thawed at 8.0 °C. Overall, this study demonstrated that increased N2O production during a single freeze-thaw event was primarily linked to antecedent conditions of high initial WFPS, soil thaw temperature, and a synergistic interplay between these two environmental parameters, and provides evidence that an increase in annual temperature and precipitation, along with the timing of precipitation, may further stimulate N2O production pathways.

Spatiotemporal changes in future precipitation of Afghanistan for shared socioeconomic pathways

Global warming induces spatially heterogeneous changes in precipitation patterns, highlighting the need to assess these changes at regional scales. This assessment is particularly critical for Afghanistan, where agriculture serves as the primary livelihood for the population. New global climate model (GCM) simulations have recently been released for the recently established shared socioeconomic pathways (SSPs). This requires evaluating projected precipitation changes under these new scenarios and subsequent policy updates. This research employed six GCMs from the CMIP6 to project spatial and temporal precipitation changes across Afghanistan under all SSPs, including SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5. The employed GCMs were bias-corrected using the Global Precipitation Climatological Center's (GPCC) monthly gridded precipitation data with a 1.0° spatial resolution. Subsequently, the climate change factor was calculated to assess precipitation changes for both the near future (2020–2059) and the distant future (2060–2099). The bias-corrected projections' multi-model ensemble (MME) revealed increased precipitation across most of Afghanistan for SSPs with higher emissions scenarios. The bias-corrected simulations showed a substantial increase in summer precipitation of around 50%, projected under SSP1-1.9 in the southwestern region, while a decline of over 50% is projected in the northwestern region until 2100. The annual precipitation in the northwest region was projected to increase up to 15% for SSP1-2.6. SSP2-4.5 showed a projected annual precipitation increase of around 20% in the southwestern and certain eastern regions in the far future. Furthermore, a substantial rise of approximately 50% in summer precipitation under SSP3-7.0 is expected in the central and western regions in the far future. However, it is crucial to note that the projected changes exhibit considerable uncertainty among different GCMs.

Hydro-sediment responses to management options under current and future climate change scenarios in Maybar watershed, South Wollo Zone, Ethiopia

Climate change coupled with inappropriate land use management is a serious environmental challenge in the highland part of Ethiopia. The aim of this study was to investigate hydro-sediment responses to management options under current and future climate change scenarios in Maybar watershed, Northern Ethiopia. We employed soil and water assessment tool (ArcSWAT 2012.10_7.24) for hydrologic modeling and CORDEX-climate data under RCP 4.5 and RCP 8.5 emission scenarios for climate projections. Soil map was prepared by digitizing soil characterization map of the watershed generated by Weigel in 1986. DEM data with 2 m spatial resolution was obtained from water and land resource center and land use classification was done through digitization of google earth images. Better agreement between calibrated SWAT simulation and observed variables was achieved. Delta change bias correction method was employed to improve the climate simulation in reproducing the observed climate variables. We found a considerable increase in annual precipitation by 18.71 % and 22.33 % for RCP 4.5 and RCP 8.5, respectively compared with the current climate conditions. Climate change induced hydro-sediment results were observed to be consistent with predicted precipitation. Under the current climatic conditions, average sediment yield at the sub-basin scale varies from negligible (under terrace complementation) to approximately more than 50 t ha−1 yr−1 with a basin average of 32 t ha−1 yr−1 (under no-terrace conditions). The implementation of management alternatives gets the dry season's hydrological behavior of the catchment improved and climate change induced sediment yield reduction. Generally, the information could possibly support decision makers and planners to implement best-fitted management options and thereby reduce current and expected aggressive sediment loss situations.

Assessment of Water Resources under Climate Change in Western Hindukush Region: A Case Study of the Upper Kabul River Basin

This study aims to estimate the surface runoff and examine the impact of climate change on water resources in the Upper Kabul River Basin (UKRB). A hydrological model was developed using the Soil and Water Assessment Tool (SWAT) from 2009 to 2019. The monthly calibration was conducted on streamflow in six stations for the period from 2010 to 2016, and the results were validated from 2017 to 2018 based on available observed data. The hydrological sensitivity parameters were further prioritized using SWAT-CUP. The uncertainty of the model was analyzed by the 95% Prediction Uncertainty (95PPU). Future projections were analyzed for the 2040s (2030–2049) and 2090s (2080–2099) compared to the baseline period (1986–2005) under two representation concentration pathways (RCP4.5, RCP8.5). Four Regional Climate Models (RCMs) were bias-corrected using the linear scaling bias correction method. The modeling results exhibited a very reasonable fit between the estimated and observed runoff in different stations, with NS values ranging from 0.54 to 0.91 in the calibration period. The future mean annual surface runoff exhibited an increase in the 2040s and 2090s compared to the baseline under both RCPs of 4.5 and 8.5 due to an increase in annual precipitation. The annual precipitation is projected to increase by 5% in the 2040s, 1% in the 2090s under RCP4.5, and by 9% in the 2040s and 2% in the 2090s under RCP8.5. The future temperature is also projected to increase and consequently lead to earlier snowmelt, resulting in a shift in the seasonal runoff peak to earlier months in the UKRB. However, the shifts in the timing of runoff could lead to significant impacts on water availability and exacerbate the water stress in this region, decreasing in summer runoff and increasing in the winter and spring runoffs. The future annual evapotranspiration is projected to increase under both scenarios; however, decreases in annual snowfall, snowmelt, sublimation, and groundwater recharge are predicted in the UKRB.

Climate change and hydropower resilience in Nepal: an integrated modeling approach in the Madi River Basin

ABSTRACT Responding to Nepal's hydropower sector's vulnerability to climate change, this study investigates its impact on energy security, focusing on the Madi River Basin's river systems. This study conducted a rigorous analysis of the basin's historical and future hydroclimatic trends, using the linear scaling method to correct inherent biases in 13 GCMs, resulting in the selection of 6 BCMs with above-satisfactory performance. Future projections reveal an increase in annual precipitation with a higher increment in SSP585 by the end of the century, and a temperature rise ranging from 1.8 to 3.5 °C from the baseline in the far future under moderate- to high-emission scenarios. These hydroclimatic projections are then forced into the calibrated soil and water assessment tool (SWAT) model with very good performance (both R2 and NSE greater than 0.8). The streamflow projection demonstrates an overall increasing trend, marked by significant flow reduction in early months and pronounced monsoon peaks. The analysis of three distinct hydropower projects reveals unique challenges and opportunities, underscoring the heterogeneous nature of projects and the need for location-specific planning and strategic management. This study provides crucial insights for sustainable development in renewable energy, laying the foundation for future research and policy in similar hydroclimatic settings.

Human-induced intensification of terrestrial water cycle in dry regions of the globe

Anthropogenic climate change (ACC) strengthens the global terrestrial water cycle (TWC) through increases in annual total precipitation (PRCPTOT) over global land. While the increase in the average global terrestrial PRCPTOT has been attributed to ACC, it is unclear whether this is equally true in dry and wet regions, given the difference in PRCPTOT changes between the two climatic regions. Here, we show the increase in PRCPTOT in dry regions is twice as fast as in wet regions of the globe during 1961–2018 in both observations and simulations. This faster increase is projected to grow with future warming, with an intensified human-induced TWC in the driest regions of the globe. We show this phenomenon can be explained by the faster warming and precipitation response rates as well as the stronger moisture transport in dry regions under ACC. Quantitative detection and attribution results show that the global increase in PRCPTOT can no longer be attributed to ACC if dry regions are excluded. From 1961–2018, the observed PRCPTOT increased by 5.63%~7.39% (2.44%~2.80%) over dry (wet) regions, and as much as 89% (as little as 5%) can be attributed to ACC. The faster ACC-induced TWC in dry regions is likely to have both beneficial and detrimental effects on dry regions of the globe, simultaneously alleviating water scarcity while increasing the risk of major flooding.

How Accurately Are Climatological Characteristics and Surface Water and Energy Balances Represented for the Colombian Amazon Basin?

Context: The Colombian Amazon basin (CAB) is characterized by having many areas with few or no in situ observations. To help fix this shortcoming, there are different gridded datasets that represent meteorological variable estimates from in situ, satellite-based, merged, and model-based products. However, before using them, it is necessary to evaluate their performance.Methods: We analyzed the capacity of five grid datasets to represent the annual cycle, the annual means, and the interquartile range of temperature and the variables that intervene in the surface water and energy balances of the CAB. The five datasets were a regional climate model (REMO) and four reanalyses (ERA40, ERA-Interim, NCEP/NCAR, and NCEP-v2). For the temperature and precipitation analyses, the Delaware, GPCP, CPC, CMAP, and CMAP-v2 datasets were also taken into account. Results: The average annual temperature cycle in the CAB has an unimodal behavior, with higher values between October and March. Only Delaware and ERA-Interim describe this behavior and exhibit values close to those of the observations. The average annual cycle of precipitation is also unimodal, with higher values between March and July. Delaware, GPCP, CPC, and ERA-Interim describe this behavior, although ERA-Interim overestimates precipitation. Additionally, the four reanalyses, especially ERA-Interim, show an unexpected trend of increase in mean annual precipitation. As for the water balance, the precipitation and runoff maps of ERA-Interim and REMO show higher values in the foothills and east of 73 degrees W, a pattern that shows better agreement with the observations than those of the other datasets. ERA-Interim, REMO, and ERA-40 meet the closure condition of both the long-term water and the energy budgets. However, REMO and ERA-Interim overestimated precipitation, ERA-40 underestimated it, and ERA-Interim overestimated solar radiation. This implies that some of the other variables for the water and energy balances are also poorly estimated. Conclusions: The five gridded datasets that allow studying surface water and energy balances are not adequate, so better models and reanalyses are required.

Water cycle changes in Czechia: a multi-source water budget perspective

Abstract. The water cycle in Czechia has been observed to be changing in recent years, with precipitation and evapotranspiration rates exhibiting a trend of acceleration. However, the spatial patterns of such changes remain poorly understood due to the heterogeneous network of ground observations. This study relied on multiple state-of-the-art reanalyses and hydrological modeling. Herein, we propose a novel method for benchmarking hydroclimatic data fusion based on water cycle budget closure. We ranked water cycle budget closure of 96 different combinations for precipitation, evapotranspiration, and runoff using CRU TS v4.06, E-OBS, ERA5-Land, mHM, NCEP/NCAR R1, PREC/L, and TerraClimate. Then, we used the best-ranked data to describe changes in the water cycle in Czechia over the last 60 years. We determined that Czechia is undergoing water cycle acceleration, evinced by increased atmospheric water fluxes. However, the increase in annual total precipitation is not as pronounced nor as consistent as evapotranspiration, resulting in an overall decrease in the runoff. Furthermore, non-parametric bootstrapping revealed that only evapotranspiration changes are statistically significant at the annual scale. At higher frequencies, we identified significant spatial heterogeneity when assessing the water cycle budget at a seasonal scale. Interestingly, the most significant temporal changes in Czechia occur during spring, while the spatial pattern of the change in median values stems from summer changes in the water cycle, which are the seasons within the months with statistically significant changes.

Detection and attribution of hydrological changes in different climatic and geomorphic regions of China

Through large-scale hydrological simulation, understanding the impact of different climatic and geomorphic conditions on hydrological variables is valuable for water and land management. However, the related study is still a challenge due to strong environmental diversity in large scale region. The physically-based, national-scale hydrological model in China was developed and validated, which considered the spatial heterogeneity of climatic and geomorphic conditions. Using the model, hydrological differences during the period 1956–2020 in 21 representative basins located in nine climatic zones and four geomorphic regions were quantified. Results showed that: 1) mean annual precipitation was strongly positively correlated with mean actual evapotranspiration, and both increased gradually from north to south. Interestingly, as annual precipitation increases, precipitation tended to be more evenly distributed. In recent decades, the northern river basins have been warming and drying, while the Heihe River basin and the cold northeast regions were under climatic warming and wetting; 2) the spatial distribution of streamflow was consistent with precipitation, but their trends were different. In cold regions affected by frozen soil, the streamflow tended to increase. On the contrary, the basins located in the Warm Temperate Zone with intense human activities and fragile ecosystem had a significant decrease in natural streamflow. As for the streamflow components, the frozen soil and karst structures contributed to the increase of the baseflow index (BFI); 3) The streamflow increase or reduction in 86% of the basins was dominated by climate change, as the contribution rate varied from 51.4% to 95.7%. Affected by the Grain to Green Programme, the streamflow of the Weihe River basin reduced significantly while the BFI increased. However, the reduction of forest, grassland and wetland areas dominated streamflow increase in the Huaihe, and Hulan River basins, and the rates were 65.3% and 66.1%, respectively.

Contemporary Climate Change in Montenegro

The Mediterranean area, including the Western Balkans, is one of the world’s most vulnerable to climate change. Many papers point out that the Mediterranean region has become warmer, more arid and with more frequent extreme weather events (high temperatures, droughts, heavy short-term rains, floods, etc.) since the middle of the 20th century, compared to the average global situation, in general. The results of the projections for the Mediterranean indicate that this trend will continue throughout the 21st century. This is a general picture of events and projections of climate change for the entire Mediterranean area, but in recent times the importance of researching smaller spatial units, subregions and individual locations of the Mediterranean has been emphasized. Second, given that the 1991‒ 2020 climate period has recently ended, the World Meteorological Organization (WMO) has recommended the use of that reference period, that is, new climatic normals in the analysis of climate element deviations. Taking into account the two mentioned facts (importance of research of smaller spatial units of the Mediterranean region and taking into account the WMO recommendation regarding the use of the new reference climate period 1991‒ 2020), this paper aimed to present the results of temperature and precipitation changes in Montenegro. Data from 10 meteorological stations, evenly distributed over the territory of the country, were used in the period 1951‒2020, as part of the Western Balkans and the Mediterranean, and the analysis included annual and daily values of the two mentioned climatic elements. When it comes to precipitation, the annual sums do not show significant changes in the observed 70-year period (1951‒2020). Changes in precipitation range from -2,3% per decade in Herceg Novi to 1,8% per decade in Rožaje. Year-on-year fluctuations are noticeable, which are common for precipitation, but we cannot talk about the aridization of Montenegro, and it should be expected in the conditions of domination of the anthropogenic greenhouse effect. The trend of annual precipitation shows a certain regionalization, namely that the southwestern and western part of Montenegro registers a decrease in precipitation (Herceg Novi, Cetinje and Nikšić), and the rest of most of the country slightly increases. If we look only at the last 30-year period (1991‒2020), the trend calculations showed that only the station Bijelo Polje registers a negative trend (-4,7% per decade), while at all other stations there was an increase in annual precipitation, the positive trend is up to 9,9% per decade (Ulcinj). In most parts of Montenegro, the annual number of wet (Rd ≥ 10 mm) and very wet days (Rd ≥ 20 mm) does not show significant changes. The only exceptions are Cetinje and Rožaje, where the number of days with Rd ≥ 10 mm decreased (-2,1 days per decade) and Rd ≥ 20 mm increased (0,7 days per decade), and in both places these changes are significant at the level of hypothesis correctness of 95% (risk level p 0,05). The only precipitation index that indicates the aridization of Montenegro is the number of dry days (SD), because the calculation results showed that during the observed period the number of SD (Rd 1 mm) increased along the trend line in all observed places. In most parts of the country there was a significant increase in the number of SD (trend is in a range of 2,0‒2,9 days per decade). Regarding changes in thermal conditions, the trend of average annual temperature indicates that there is significant warming in Montenegro, ranging from 0,13 °C per decade in Herceg Novi and Cetinje to as much as 0,70 °C per decade in Rožaje. For the last 30-year period (1991‒2020), the obtained results indicate a more intense warming in relation to the entire observed period, in general. During the previous 30 years, the most intensive trend of increasing average annual temperature was registered in places in the northeast of Montenegro: Bijelo Polje 1,02 °C per decade and Rožaje 0,85 °C per decade. Temperature indices also indicate an increase in temperature. The increase in the number of summer and tropical days, as well as tropical nights, and the decrease in the number of frost and ice days, clearly indicates that there is a tendency of warming in Montenegro in the previous 70 years (1951‒2020). Thus, all considered temperature indices indicate a warmer climate. Finally, a simple difference was used to determine the quantitative magnitude of temperature and precipitation changes between the last two climate periods: 1991‒2020 (new climate normal) and 1961‒1990 (old climate normal). On an annual basis, previous results have shown that the new climatic normals (1991‒ 2020) have almost the same values as the previous ones (1961‒1990). However, the analysis of all temperature parameters indicates that the new climate normals are „warmer“ compared to the previous ones. For example, in relation to the old climatic norm (1961‒1990), the average annual temperature for the period 1991‒2020 it is higher in Podgorica by 1,1 °C, and in Žabljak by 1,3 °C. Has the climate of Montenegro changed? Simply put, the climate of Montenegro has become warmer, but not more arid or humid, that is, nothing worrying is happening with the amount of precipitation and the number of considered precipitation days.

Vegetation quality and its change in the Three North Shelterbelt Forest region in China

The Three North Shelterbelt Forest (TNSF) region in northern China is the largest artificial afforestation area in the world. Vegetation quality in the TNSF region has been improved greatly in recent years. This article presents a new approach to characterize vegetation quality by coupling vegetation productivity and coverage, examining the trend of vegetation quality from 2000 to 2021 at 1 km × 1 km spatial resolution by the linear regression trend method, and analyzing the driving forces of that trend. The results revealed a significant spatial difference of vegetation quality. Higher vegetation quality was found in the east and southeast of the TNSF region. Improvement of vegetation quality was found in approximately 80% area of the TNSF region, at a rate of 0 ∼ 52 g C m−2yr−1 with α = 0.05 significance between 2000 and 2021. Vegetation quality deteriorated in a few areas. The increase in CO2 concentrations and annual precipitation facilitated the improvement of vegetation quality, but also human efforts in ecological protection and restoration accelerated the improvement of vegetation quality under the current climate change background. The results might contribute to designing future ecological projects and the scientific adjustment of vegetation restoration strategies.

Assessment of climate change impacts for two tributary basins of the Irtysh River in Kazakhstan

Information about the climate change impacts on river discharge of 2 tributary basins of the Irtysh River, the Oba and Ulbi, is important for effective management of the water resources of the Shulba reservoir in Kazakhstan. The main aim of the study was to investigate potential changes in water resource availability in the study basins. To assess the projected changes, the process-based eco-hydrological model SWIM was used under 2 Representative Concentration Pathway (RCP) climate scenarios obtained from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP). Our results show an increase in mean annual temperature of 6.1°C, an increase in average annual precipitation of 7.5 to 14%, an increase in annual average discharge for the Oba (6 to 8%) and smaller discharge changes (below 5%) for the Ulbi at the end of the century under RCP8.5—a scenario of comparatively high greenhouse gas emissions—compared to the reference period (1981-2010). Seasonal variations are marked by the peak discharge occurring up to a month earlier, a decrease in the duration of snow accumulation and a reduction in discharge during the summer months. The peak discharge period is prolonged in time, and a slight increase in river discharge could be expected from October to December. Possible future changes in climate may have serious impacts on water resources, agriculture and economic development in the case study basins. The results of this study can be extrapolated to other neighboring basins in Kazakhstan with similar climatic and geophysical characteristics.

Assessment of climate change impacts on hydrological processes in the Usangu catchment of Tanzania under CMIP6 scenarios

Abstract Climate change is anticipated to have long-term effects on hydrological processes and patterns, leading to water stress in agroecological catchments. Climate change escalates water scarcity in the Usangu catchment, as evidenced by the drying up of rivers during the dry season. Therefore, this study was undertaken to assess climate change impacts on hydrology by utilizing the Soil Water Assessment Tool (SWAT) model and an ensemble mean of five Global Circulation Models (GCMs) under two shared socio-economic pathway (SSP) emission scenarios. Downscaling of GCMs was performed by the LARS-WG statistical downscaling tool. In comparison to the baseline period, short rain intervals are expected to occur between 2030 and 2060, with a mean annual precipitation increase of 7 and 17% in SSP 2–4.5 and SSP 5–8.5, respectively. Maximum and minimum temperatures are expected to rise by 0.6–2 °C. Corresponding to future temperature increases, evapotranspiration would increase to about 30% and decrease water yield and groundwater recharge by 7 and 26% in SSP 2–4.5 than in SSP 5–8.5. However, the effect of precipitation increase is shown by increased surface runoff and streamflow during wetter months. These findings provide watershed managers with crucial information for planning and managing the catchment in light of a changing climate.

Spatial and temporal characteristics of past droughts in New Brunswick (1971–2020)

AbstractThis study aimed to provide a historical picture from 1971 to 2020 of the state of droughts in New Brunswick (NB). More specifically, we wished to determine whether there were statistically significant trends using two drought indices: the Standardized Precipitation Index (SPI) and the Standardized Precipitation‐Evapotranspiration Index (SPEI). Monthly precipitation (rain and snow) and average maximum and minimum temperatures were obtained from 10 stations located in New Brunswick. Then, we applied Mann–Kendall and Sen's Slope's nonparametric tests to these two indices at a 1‐, 3‐, 6‐ and 12‐month timescale. The results have shown that the average value for the SPI and SPEI evolution throughout the study period indicated a decrease in indices values (at 95% confidence level). The temporal evolution of the SPI and SPEI were similar at various timescales regarding severities and intensities. However, there were still slight differences in the fluctuation values, especially during the last 20 years of the study period. At a 12‐month timescale, both indices indicated the driest years as being 2020, 2001 and 2004. The SPEI Miramichi, Saint John and Moncton stations had maximum negative MK values (−0.259, −0.221 and −0.215), respectively. As for spatial distribution, four stations located in the south stood out with the highest increase in dry conditions and significantly negative trends (meaning increased drought in this case). Stations in the northern part of the province (Bathurst and Charlo) show non‐significant trends. This study suggests a slight drought increase trend exists in New Brunswick, while an increase in annual precipitation is expected between 42 and 324 mm by 2100 according to climate scenario RCP8.5 of CMIP6.

Predictive Study on Extreme Precipitation Trends in Henan and Their Impact on Population Exposure

This study employs precipitation data sets from historical trials on 20 CMIP6 global climate models and four shared socioeconomic pathway scenario trials (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) to predict trends in extreme precipitation changes in Henan Province quantitatively, while ascertaining the risk of population exposure to extreme precipitation in this area. The capacity of the CMIP6 models to simulate extreme precipitation indices from 1985 to 2014 is assessed using CN05.1 daily precipitation observational data. The correlation coefficients of the multi-model ensemble median’s simulation of the extreme precipitation indices are approximately 0.8, with a standard deviation ratio closer to 1 compared with the single models, demonstrating superior modeling ability. Analyses using the multi-model ensemble median demonstrate an overall increase in the total amount, frequency, and intensity of extreme precipitation in Henan throughout this century, particularly in its southern regions; in the mid-century high-emission scenario (SSP5-8.5), the maximum increase in annual total precipitation exceeds 150 mm, and it can be over 250 mm in the late-century period. For the entire province, the maximum five-day precipitation increase relative to the historical period is nearly 25 mm in the late-century SSP5-8.5 scenario. The spatiotemporal concentration of precipitation will significantly increase, heightening the risk of flood disasters. Comparative analysis reveals that, under the same population prediction, the total population exposure will be higher in high radiative forcing scenarios than in low radiative forcing scenarios, especially in Kaifeng City, where the total population exposure in SSP1 and SSP5-8.5 exceeds that in SSP1-2.6 by 2 million person-days. However, in the same radiative forcing scenario, the total population exposure in the development pathway dominated by traditional fossil fuels (SSP5) will not be significantly higher than that in the sustainable development pathway (SSP1), indicating that population activity in this century will not be the main contributor to changes in total exposure. Overall, for Henan, in the same population forecast scenario, population exposure to extreme precipitation will gradually rise with global warming.

Moisture amplification of the high-altitude deglacial warming

In response to anthropogenic warming, glaciers are shrinking almost everywhere, endangering water accessibility in areas located downstream. Glacier fluctuations are at first order controlled by local precipitation and temperature, but large uncertainties persist on the potential role of local moisture in amplifying or dampening temperature changes at high-elevation. Here, we combine glacier extents and Sea Surface Temperature (SST) during the Last Glacial Maximum (LGM) to quantify altitudinal thermal gradients (lapse rate) from 40°N to 40°S along the American Cordillera. We also constrain modern lapse rates based on present day temperature and SST database to explore how the lapse rate has changed since the LGM along this North South transect. Based on proxy-based quantitative paleo-precipitation estimations above 2000 m, we investigate how these lapse rate changes compare with moisture modifications around the Cordillera and discuss the mechanisms that potentially controlled lapse rate changes during the post-LGM deglacial warming.We find that lapse rate changes are linearly related to changes in precipitation and derive a quantitative relationship between these two parameters. To further explore the processes involved in controlling lapse rate variations, we use the IPSL global climate model outputs, for the LGM and pre-industrial states in this region. The IPSL model also yields a shallower modern lapse rate in the wetter tropical region, confirming the observed correlation between precipitation changes and lapse rate variations. The IPSL model also supports a close coupling of continental relative moisture and mean annual precipitation in the studied area, indicating that moisture is involved in the precipitation – lapse rate relationship. Our results suggest that future warming may be enhanced in high altitude regions where precipitation is expected to increase. Using our most reliable relationship linking precipitation and lapse rate changes, we conclude that, assuming a 1 °C warming at sea level, a mean annual precipitation increases of 500 mm.a−1 could lead to a warming amplification of 4.1 ± 0.8 °C at 4000 m asl (mean elevation of modern glaciers). In this case, a 2 °C warming at sea level would yield >6 °C degrees warming at 4000 m asl. This study therefore confirms that special attention should be given to the climate projections of glacier melting in tropical and mid latitude regions.