HadGEM2-ES Model Research Articles

Simulating the climate change effects on the Karaj Dam basin: hydrological behavior and runoff

ABSTRACT This study has used Coupled Model Intercomparison Project Phase 5 (CMIP5) and Coupled Model Intercomparison Project Phase 6 (CMIP6). Hence, the runoff simulation was done in near-future period (2030–2050) scenarios by applying climate change conditions for HadGEM2-ES model under three representative concentration pathways RCP2.6, 4.5 and 8.5 scenarios and for HadGEM3-GC31-LL model under SSP1-2.6, SSP2-4.5 and SSP5-8.5 scenarios. Examining the climatic precipitation variables and minimum and maximum temperature under climate change conditions showed a temperature increase of 1.51–2.91 °C for all models and scenarios and a precipitation decrease of 0.05–11.15% for most of them, and the SWAT model simulation showed a runoff decrease in all four stations under SSP scenarios and a runoff increase in three stations under RCP scenarios. Since the climate data for SSP scenarios have become available only recently, results of this study predict that the overall future flow will vary in the −5 to 28% range, resulting in a 5–35% decrease in the flow and, hence, a decrease in the inflow to the dam reservoir. Based on the results, there is a possibility of a 5–30% reduction of the runoff entering the dam reservoir.

Estimating IDF curves under changing climate conditions for different climate regions

Abstract Although climate models can highlight potential shifts in intensity–duration–frequency (IDF) curves, their limited geographical and temporal resolutions limit their direct use in predicting sub-daily heavy precipitation. To use global or regional model outputs to predict urban short-term precipitation, approaches that give the requisite level of spatial and temporal downscaling are required, and these processes remain one of the difficulties that have demanded intensive effort in recent years. Although no novel methods are given in this work, there are few studies in the literature that investigate the impact of climate change on the analysis and design of infrastructure-related engineering structures. Therefore, the purpose of this research is to determine the potential changes in IDF curves because of climate change. The equidistance quantile matching method was used to turn future rainfall forecast data from global climate models (HadGEM2-ES, MPI-ESM-MR, and GFDL-ESM2M) corresponding to RCP4.5 and RCP8.5 scenarios into standard duration rainfall data, and new IDF curves were generated. These IDF curves corresponded very well with those generated from observed data (R2 ≈ 1). The HadGEM2-ES model predicts up to a 25% rise in rainfall intensity, whereas the other two models expect up to a 50% drop.

Predicting Climate Change Impacts on Candelilla (Euphorbia antisyphilitica Zucc.) for Mexico: An Approach for Mexico’s Primary Harvest Area

Candelilla (Euphorbia antisyphilitica Zucc.) is a non-timber forest resource of ecological and economic importance in the arid zones of Mexico due to the commercialization of its wax for industrial purposes. The objectives of this study were (i) to delimit areas of current and projected future candelilla habitat suitability in Mexico and in the state of Coahuila, (ii) to determine the most important variables that define candelilla habitat, and (iii) to propose areas for candelilla conservation under climate change conditions in Coahuila. Records of candelilla presence, current and future bioclimatic layers from the MPIESM-LR and HadGEM2-ES models with two scenarios RCP 4.5 and 8.5, were used to create species distribution models with soil and topographical variables. MaxEnt software was used to project current habitat suitability zones under climate change. We estimated the current surface area of candelilla in Mexico to be 79,336.87 km2, and for Coahuila 25,620.75 km2. In Coahuila, using the MPIESM-LR model for 2050, the estimate was 20,177.67 km2 and 17,079.61 km2 for RCP scenarios 4.5 and 8.5; while for 2070, the estimate was 12,487.18 km2 and 9812.94 km2 for RCP scenarios 4.5 and 8.5. For the HadGEM2-ES model for 2050, the estimate was 20,066.40 km2 and 17,079.61 km2; for 2070 it was 17,156.02 km2 and 16,073.70 km2. As proposed areas for conservation of candelilla in the face of climate change, we estimated 5435.06 km2 and 3636.96 km2. The study area was located in the northwest and center of the state of Coahuila, near the natural protected areas of Ocampo and Bajo Rio San Juan, areas that are resilient to climate change. The results obtained provide information on the environmental and site conditions for the establishment of candelilla in Mexico, as well as the geographical areas, such as Sierra y Cañon de Jimulco, Tomás Garrido, 026 Bajo Río San Juan, Zapalinamé, Zapalinamé, and Cumbres de Monterrey Restoration Zones for the conservation of the species under local climate change scenarios. In addition, new areas in the northwest and center of Coahuila could be used to establish new protected areas for this economically important species.

Protected area planning to conserve biodiversity in an uncertain future.

Protected areas are a key instrument for conservation. Despite this, they are vulnerable to risks associated with weak governance, land-use intensification, and climate change. We used a novel hierarchical optimization approach to identify priority areas for expanding the global protected area system that explicitly accounted for such risks while maximizing protection of all known terrestrial vertebrate species. To incorporate risk categories, we built on the minimum set problem, where the objective is to reach species distribution protection targets while accounting for 1 constraint, such as land cost or area. We expanded this approach to include multiple objectives accounting for risk in the problem formulation by treating each risk layer as a separate objective in the problem formulation. Reducing exposure to these risks required expanding the area of the global protected area system by 1.6% while still meeting conservation targets. Incorporating risks from weak governance drove the greatest changes in spatial priorities for protection, and incorporating risks from climate change required the largest increase (2.52%) in global protected area. Conserving wide-ranging species required countries with relatively strong governance to protect more land when they bordered nations with comparatively weak governance. Our results underscore the need for cross-jurisdictional coordination and demonstrate how risk can be efficiently incorporated into conservation planning. Planeación de las áreas protegidas para conservar la biodiversidad en un futuro incierto.

PROJECTION OF CLIMATE CHANGE IMPACTS ON NET PRIMARY PRODUCTIVITY OF THE LEGAL AMAZON – BRAZIL

The Amazon Rainforest is one of the main carbon sinks (CO2) on the planet. However, recently, due to anthropic activities and climate change, it has lost its stability in CO2 absorption. Therefore, understanding the dynamics of future climate change scenarios becomes essential. We assess the influence of future climate change scenarios on NPP (biomass) levels in the Amazon Forest using ML models. The tested models were Bayesian, Linear Model, and Random Forest. The current scenario was evaluated using 19 bioclimatic covariates (worldclim dataset). While the future scenarios were based on RCPs 2.6 and 8.5 (based on the models of the MIROC5 and HadGEM2-ES models). Random Forest had the best performance statistic (R² = 0.71 in training and 0.68 in holdout-test). The climate change scenarios will imply an increase in the average NPP for the Amazon forest, especially with greater intensification in RCP 2.6 (2 and 7.69 % for the HadGEM2-ES and MIROC5 models, respectively). Forests (Evergreen Broadleaf Forests areas) will have greater carbon fixation capacity. In general, the Amazon forest will have increased carbon fixation capacity by the end of the century.

Rainfall dynamics in the Sudano-Sahelian zone of Nigeria under RCP 8.5

The study analysed the historical (1961–90) and projected rainfall variability for the rainy season expected in the near future (2021–50) at selected locations within the Komadugu-Yobe and Sokoto-Rima River Basins in the Sudano-Sahelian zone of northern Nigeria. Three models were utilised, and analyses were based on Representative Concentration Pathway (RCP) 8.5. Projected changes in mean, level of variability and distribution of rainfall were analysed using the Relative Percentage Change Method and the Precipitation Concentration Index (PCI), while the performance of the models was evaluated using the Nash–Sutcliffe Efficiency (NSE) index. The results show that changes in mean rainfall will be predominantly negative, with a minimum and maximum level of change of ˗1.02 per cent at Nguru, and ˗70.4 per cent at Jos, based on the IPSL-CM5A and HadGEM2-ES models, respectively. The rainy season of the baseline period varied between low and moderate variability, while the near future ranges between low and high levels of variability. The validation indicates acceptable levels of performance, with most values ranging between 0.0 and 1.0. The PCI for the near future suggests that the rainy season will be mainly characterised by uniform and near-uniform rainfall distribution. Hence, the projected negative changes and high variability of rainfall at some locations call for the development of an Adaptive Benefit Mechanism that will minimise future natural resource conflicts.

Modelling climate change impacts on crop production in food insecure regions: The case of Niger

To quantify the impacts of climate change on agricultural systems and to support policy processes and farm level decisions, the agricultural meteorology community is extensively applying climate-crop modelling approaches. The herein study evaluates the impact of two climate change scenarios (Representative Concentration Pathways-RCPs 4.5 and 8.5) on main crops (millet, sorghum and cowpea) grown in two agroclimatological regions (Soudano-Sahelian and Sahel) in the Republic of Niger. Climate projections using HadGEM2-ES model show increasing precipitation trends of up to + 30 % under RCP 8.5 in Birni N′Konni (Soudano-Sahelian) and a decrease of 1 % under RCP 4.5 in Mare de Tabalak (Sahel) when comparing the 2021–30 and 2071–80 periods. The number of dry days and heavy rainfall events during the wet-season are also expected to gain in frequency over the century. As a result, the productivity of major crops is threatened, with potential dire consequences for national food security and the income of millions. The emerging findings of the crop-modelling work using AquaCrop show decrease/increase yield trends for millet, sorghum and cowpea of about 0 to − 50 %, + 5 to − 20 %, + 11 to + 18 %, respectively, by the end of the century (2060–80), depending on the agroclimatic zone, sowing date and RCP. Overall, the emerging findings of this work can be used to inform agricultural transformation and adaptation to climate change by promoting a higher resilience against both excess of water (due to high rainfall events) and lack of water resources (due to extended dry periods).

Modelling climate change impacts at a drinking water reservoir in Turkey and implications for reservoir management in semi-arid regions.

Climate change can have severe impacts on the water availability in semi-arid regions. In this study, we assessed the impact of climatic changes on water availability in the Altınapa Reservoir Watershed, located in the Konya province, south-central Turkey. Altınapa Reservoir supplies drinking water to Konya, a city of about 2 million population. We investigated possible changes in streamflow and reservoir storage over 2021-2098 under two representative concentration pathway scenarios (RCP4.5 and RCP8.5) developed based on GFDL-ESM2M, HadGEM2-ES, and MPI-ESM-MR global circulation models. We used a physically based model (SWAT-Soil and Water Assessment Tool) for understanding the hydrologic response of the basin to climatic changes. Results show that upward trends in air temperatures in the range of 0.01-0.04°C/year and 0.005-0.06°C/year are expected from 2021 to 2098 under the RCP4.5 and RCP8.5 scenarios, respectively. According to the HadGEM2-ES model, precipitation and streamflow would show a downward trend at a rate of 0.96mm/year and 0.007 m3/s/year under the RCP4.5 scenario and at a rate of 1.62mm/year and 0.01 m3/s/year under the RCP8.5 scenario, respectively. GFDL-ESM2M and MPI-ESM-MR models project upward trends in precipitation and streamflow under the RCP4.5 scenario (in the range of 0.64-1.28mm/year and 0.0003-0.006 m3/s/year, respectively), and downward trends under the RCP8.5 scenario (in the range of 0.47-0.76mm/year and 0.0015-0.003 m3/s/year, respectively). Reservoir storage is projected to increase slightly according to GFDL-ESM2M model and decrease according to the HadGEM2-ES, and MPI-ESM-MR models under both scenarios. Precipitation, streamflow, and reservoir storage predictions of GFDL-ESM2M and MPI-ESM-MR models are considerably lower than those observed in the basin in recent decades, showing that water resources will decrease in the future. The changes in water withdrawal patterns could cause further reductions in water availability. Good resilience to climate change can be achieved by a flexible water management system and by reducing water consumption and water losses in the watershed and from the reservoirs.

Evaluating carbon and water fluxes and stocks in Brazil under changing climate and refined regional scenarios for changes in land use

Climate change and land-use change can alter the role of natural vegetation as a sink or source of atmospheric carbon. In this work, we evaluate the response of water and carbon fluxes and stocks in Brazilian biomes as a proxy for ecosystem services of regional climate regulation under two contrasting future scenarios: a sustainable development scenario, where some deforested areas are restored by vegetation regrowth combined with a low representative concentration pathway, and a pessimistic scenario, where there is still high deforestation rates and strong climate change. We used refined regional scenarios for land-use change in Brazil, together with climate projections of the HADGEM2-ES model for RCPs 2.6 and 8.5 to drive a land surface model and assess possible future impacts in surface fluxes. Our results show that drying climate and shifts of natural vegetation into anthropogenic land use might shift part of upperstory biomass into understory biomass, which can be more vulnerable to dry events. The simulations also show that climate change appears to drive most of the water balance changes compared to land-use change, especially over the Amazon.

Modeling the effects of future climate and land-use changes on streamflow in a headwater basin in the Brazilian Caatinga biome

Projected climate changes integrated into future land-use changes are extremely complex and hard to estimate, especially for basins located in semiarid environments. This work aims to estimate streamflow and the future water yield using climate prediction and land-use changes in the Salgado River basin for the 2030 − 2060 period. In this study, the applicability of the Soil and Water Assessment Tool (SWAT) and Land Change Modeler models was verified to estimate flows and land use and cover for the studied basin. Calibration and validation of the SWAT model are used on a monthly basis for 1986 − 2017, with a calibration period from 1986 to 2006 and a validation period from 2007 − 2017. Land use and cover analysis is performed for the 1985 − 2000 period, and future land use and cover is predicted using the land change model for 2050. In addition, future hydrological modeling of the geographical distribution of the water yield is performed for each subbasin of the Salgado River basin from the 2030 to 2060 period. The results of land use and cover changes show that the pasture class was the one that showed the most significant increase in the basin due to recent changes in land use and cover. The results showed that the HadGEM2-ES model presented a minor difference in the representative concentration pathways (RCP) 2.6, which indicates that this model is the most suitable for rainfall-runoff simulations in the region.

Impact of Climate Change on the Yield and Water Footprint of Winter Wheat in the Haihe River Basin, China

Climate change can impact the yield and water footprint of crops. Therefore, assessing such impacts carries great significance for regional water and food security. This study validated and verified the variety parameters of winter wheat for the Decision Support System for Agrotechnology Transfer (DSSAT) model, using the long-term (1993–2013) growth and yield data observed from six agricultural experiment stations in the Haihe River Basin (HRB), China. The growth process was simulated under three representative concentration pathways (RCPs), named RCP2.6, RCP4.5, and RCP8.5—climate scenarios driven by the HadGEM2-ES model. The variety parameters of winter wheat showed high accuracy in the simulation of the anthesis and maturity dates, and could be used for long-term prediction of the growth process. The trends of climate change had positive impacts on the water footprint of winter wheat but adverse impacts on the yield. The growing period was shortened by 3.6 days, 4.7 days, and 5.0 days per decade in the RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively, due to the rapid accumulation of heat. The yield would be increased in lower emissions scenarios (17% in RCP2.6), but decreased in high-emissions scenarios due to high temperatures, which may restrict the growth of wheat. The water footprint was decreased by 10%, 11%, and 13% in the RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively, indicating that the water-use efficiency could be improved in the future. The results showed broad application prospects of the DSSAT model in simulating the response of crop growth to climate change.

Estimating Optimal Design Frequency and Future Hydrological Risk in Local River Basins According to RCP Scenarios

In South Korea, flood damage mainly occurs around rivers; thus, it is necessary to determine the optimal design frequency for river basins to prevent flood damage. However, there are not enough studies showing the effect of climate change on hydrologic design frequency. Therefore, to estimate the optimal design frequency according to future climate change scenarios, this study examined urban flooding area and extreme rainfall frequency that can change in the future. After estimating the optimal design frequency, hydrological risks of 413 local river basins were evaluated according to Representative Concentration Pathway (RCP) scenarios 4.5 and 8.5 after regenerating daily rainfalls from the HadGEM2-ES model into hourly rainfalls using the Poisson cluster. For the RCP 4.5, hydrological risks increased relative to the established design frequency by 3.13% on average. For the RCP 8.5, hydrological risks increased by 2.80% on average. The hydrological risks increased by 4.58% in the P2(2040–2069) period for the RCP 4.5, and by 4.39% in the P1 (2021–2039) period for the RCP 8.5. These results suggest that the hydrologic design frequency in the future will likely decrease, and the safety of river basins will also decrease.

Impacts of greenhouse gases and deforestation in Amazon Basin climate extreme indices

To evaluate the individual and combined impacts of increasing greenhouse gases and deforestation on extreme precipitation events in the Amazon Basin, we carried out 4 numerical experiments with the regional Eta model forced from the initial and boundary conditions of the global HadGEM2-ES model: (1) control experiment (CTRL); (2) RCP8.5 scenario; (3) DEFOREST scenario; and (4) RCP8.5+DEFOREST scenario. To analyze changes in extreme rainy events associated with the increase in greenhouse gases, deforestation, and their combined effect, anomalies were calculated from the sensitivity and control experiments. In the RCP8.5 scenario, there was an increase in the maximum number of consecutive dry days (CDD), a reduction in the maximum number of consecutive wet days (CWD), a reduction in total annual precipitation (PRCPTOT), and an increase in the maximum precipitation accumulated in 5 consecutive days (RX5Day). The DEFOREST scenario evidenced an increased CDD, and a reduction in the other indices (CWD, PRCPTOT, and RX5Day). Furthermore, the RCP8.5+DEFOREST scenario exhibited an increased CDD, and a reduction in the other indices (CWD, PRCPTOT, and RX5Day), but with more intense increases and reductions than observed in the DEFOREST scenario. In general, towards the end of the 21st century, the 3 scenarios are projected to increase the drought period, mainly on the boundary between the Brazilian states of Amazonas and Pará.

EFFECT OF CLIMATE CHANGE ON THE DEMOGRAPHICS OF CURITIBA PRISMATICA (D. LEGRAND) SALYWON & LANDRUM: AN ENDEMIC ARAUCARIA FOREST SPECIES

With the occurrence of intensive climate change, there is a risk of irreversible damage to global biodiversity, resulting in reduction of geographical distribution and species extinction. The objective of this study was to evaluate the current distribution and the future projection of the areas of occurrence of Curitiba prismatica. Current occurrence data accessed in the SpeciesLink database and scientific studies were collected, which were correlated with the bioclimatic data available in WorldClim, for the current and future periods (2070), in the optimistic (RCP 4.5) and pessimistic scenarios (RCP 8.5) of the HadGEM2-ES model. In the current scenario, a species presents suitability restricted to mixed ombrophilous forest (MOF), with limited distribution to the center-south of the state of Paraná and the north of the state of Santa Catarina. For the future, there were reductions in the areas of climatic susceptibility for the species, both in the optimistic and pessimistic scenarios. In the RCP 4.5 scenario, the predictive reduction was found in the midwest region of Paraná, unlike the RCP 8.5 scenario, which showed a low reduction in this region. Therefore, in the future, areas with high suitability will tend to contract, but restricted to the regions of the first and second plateau of Paraná and the north of Santa Catarina. In this sense, these areas are indicated for commercial planting and in situ and ex situ conservation of the species.

Modeling the spatial distribution of a tropical dry forest tree facing climate change

Species distribution models have become an essential tool for the selection of conservation areas. Given this perspective, this research aimed to analyze the dynamics of the fundamental niche of Ziziphus joazeiro Mart. facing climate change. The MaxEnt algorithm was used to correlate species points of occurrence with bioclimatic variables of four periods: Middle Holocene, current period, and the optimistic and pessimistic future scenarios of the HadGEM2-ES model of general atmospheric circulation. The accuracy of the predictions and the influence of the variables was evaluated using the area under the curve (AUC index) and the Jackknife test. The predictions showed high precision (AUC > 0.895), and the bioclimatic variables related to precipitation were the ones that most contributed to determining potential areas for the occurrence of the species. A reduction of more than 60% was observed in the area with climatic suitability for the occurrence of Z. joazeiro, over time. The range that comprises the central region of the distribution of the species stands out as the region with the greatest suitability, as projected for the current and future period, this being the area that should receive the most attention for the conservation programs of the species.

Effect of Climate Change on the Distribution of Zoonotic Cutaneous Leishmaniasis in Iraq

Phlebotomus papatasi sand fly is the main vector of Zoonotic Cutaneous Leishmaniasis (ZCL) in Iraq. The aim of this study was to assess and predict the effects of climate change on the distribution of the cutaneous leishmaniasis (CL) cases and the main vector presently and in the future. Data of the CL cases were collected for the period (2000-2018) in addition to sand fly (SF) abundance. Geographic information system, R studio and MaxEnt (Maximum entropy niche model) software were used for analysis and predict effect of (elevation, population, Bio1-19, and Bio28-35) on CL cases distribution and SF occurrence. HadGEM2-ES model with two climate change scenarios, RCP 4.5 and RCP 8.5 were used for future projections 2050. The results showed that the CL case trend was increased over the period (2000-2018) with highest peak observed in 2017. Incidence rate for same period was varied and increased. Near perfect crimination (SF as vector) led to high predictive performance of the model in 2050. The study concluded that the climate conditions are the major determinants of ZCL distribution and SF occurrence. Habitats suitability for the ZCL and SF will be stay in the future comparing with the current conditions. Evaluation of the effect of environmental conditions and bioclimatic factors on ZCL distribution and SF occurrence may provide a guide for CL prevention and control programmers.

An assessment of Iran's seasonal temperature probability distribution variations in the future decades

Global warming in arid and semi-arid regions such as Iran is characterized by water scarcity and drought. In this paper, climate change impact on seasonal maximum and minimum temperature was done. To do so, three global climate models including CANESM2, GFDL-ESM2M, and HADGEM2-ES were used to simulate future climate change across Iran. SDSM model was used to downscale the CANESM2 model data. The data of GFDL-ESM2M and HADGEM2-ES models were downloaded from CORDEX database. In the present paper, the time period of 1976–2005 was considered as the base period and the time scales of 2011–2040, 2041–2070, and 2071–2099 as the future periods. The RCP2.6, RCP4.5, and RCP8.5 scenarios were chosen to future projection of minimum and maximum temperature. Taylor diagram was used to model evaluation. The results showed that the performance of SDSM model in minimum and maximum temperature downscaling in the base period is better than CORDEX database. One reason could be the smaller number of stations selected compared to CORDEX grid points. Results showed the highest positive anomalies of average maximum and minimum temperature compared to the base period studied (1976–2005), related to time period 2071–2099 and RCP8.5 by 6.69 and 6.61°C, respectively. The results showed that the maximum temperature will increase between 0.82 and 3.7°C on average depending on the season, time, and type of scenario. This value is in the range of 0.4–3.87°C for the minimum temperature. Results showed that hot days will increase. Results also showed that cold nights of winter in the coming decades will be warmer than the base period. The results also indicate that the frequency distributions of minimum and maximum temperatures in the future decades will shift to warmer temperatures in response to global warming.

Climate Change and Sensitivity of Surface Water Resources in the Mekrou Sub-Watershed at the Yakrigourou Outlet (North Benin / West Africa)

The present work aims to contribute to a better understanding of the impacts of climate change on the availability of surface water resources in the Mékrou sub-basin at the Yakrigourou outlet in northern Benin. To achieve this objective, descriptive statistical methods were applied to hydro-climatological data. The historical data were taken from the Météo-Bénin database and from the General Directorate of Water in Benin. The simulation data are those of the HadGEM2-ES climate model under the RCP 4.5 and RCP 8.5 scenarios and then at horizons 50 (2041 to 2060) and 70 (2061 to 2080). The results show that the period from 1965 to 2018 is globally characterised by a strong irregularity of rainfall with a decreasing trend and a multiplication of dry years estimated at 54%. In the same way, the runoff decrease about 5.8 m³/s during the decade 2007-2016. Under the most pessimistic scenario (RCP8.5) and compared to the reference period (1971-1990), the HadGEM2-ES model predicts an increase in annual precipitation estimated at 8.29% by 2041-2060 and 13.83% by 2061-2080. As regards temperature, there could be an increase of 2.4°C by 2041-2060 and 3.7°C by 2061-2080. These climatic events affect the availability of surface water resources in the sub-basin.

Spatiotemporal variation and tendency analysis on rainfall erosivity in the Loess Plateau of China

Abstract Rainfall erosivity is an important factor to be considered when predicting soil erosion. Precipitation data for 1971–2010 from 39 stations located in the Loess Plateau of China were collected to calculate the spatiotemporal variability of rainfall erosivity, and the long-term tendency of the erosivity was predicted using data from the HadGEM2-ES model. Statistical analyses were done using Mann–Kendall statistic tests and ordinary Kriging interpolation. The results showed that the annual mean rainfall erosivity in the Loess Plateau decreased from 1,286.02 MJ mm hm−2 h−1 a−1 in 1971–1990 to 1,201.46 MJ mm hm−2 h−1 a−1 in 1991–2010 and mainly occurred in July to August. The rainfall erosivity decreased from the southeast to the northwest of the Loess Plateau and was closely related to the annual precipitation amount. However, the effect of annual precipitation on rainfall erosivity weakened under climate change: the annual precipitation increased and the rainfall erosivity decreased. Climate change, however, had little influence on the spatial variation in rainfall erosivity in the Loess Plateau. The results obtained can facilitate the prediction of spatial and temporal variations in soil erosion in the Loess Plateau.

The Extratropical Linear Step Response to Tropical Precipitation Anomalies and Its Use in Constraining Projected Circulation Changes under Climate Warming

AbstractRossby wave trains triggered by tropical convection strongly affect the atmospheric circulation in the extratropics. Using daily gridded observational and reanalysis data, we demonstrate that a technique based on linear response theory effectively captures the linear response in 250-hPa geopotential height anomalies in the Northern Hemisphere using examples of steplike changes in precipitation over selected tropical areas during boreal winter. Application of this method to six models from phase 5 of the Coupled Model Intercomparison Project (CMIP5), using the same tropical forcing, reveals a large intermodel spread in the linear response associated with intermodel differences in Rossby waveguide structure. The technique is then applied to a projected tropicswide precipitation change in the HadGEM2-ES model during 2025–45 December–February, a period corresponding to a 2°C rise in the mean global temperature under the RCP8.5 scenario. The response is found to depend on whether the mean state underlying the technique is calculated using observations, the present-day simulation, or the future projection; indeed, the bias in extratropical response to tropical precipitation because of errors in the basic state is much larger than the projected change in extratropical circulation itself. We therefore propose the linear step response method as a semiempirical method of making near-term future projections of the extratropical circulation, which should assist in quantifying uncertainty in such projections.