scholarly journals Projection of important climate variables in large cities under the CMIP5–RCP scenarios using SDSM and fuzzy downscaling models

Author(s):  
Hossein Shakeri ◽  
Homayoun Motiee ◽  
Edward McBean

Abstract Climate change impacts are among the many challenges facing management of large cities. This study assesses the important climate variables under climate change impacts in Tehran, Iran, for 2021–2040. Eight Coupled Model Intercomparison Project, Phase 5 (CMIP5) models under the scenarios of Representative Concentration Pathway 2.6 (RCP2.6), RCP4.5, and RCP8.5 were used, and seven climate variables were projected utilizing the Fuzzy DownScaling Model (FDSM) and the Statistical DownScaling Model (SDSM). The FDSM and SDSM results underline the high performance of both models and the important capability of the FDSM, showing the increasing trend of annual changes in mean temperature (Tmean) and maximum temperature (Tmax), precipitation, and the mean wind speed (Wmean). The maximum increase of annual average in Tmean and Tmax and the Wmean among all scenarios will be in the order of 1.29 °C, 1.57 °C, and 0.8 m/s (for RCP8.5), and also the maximum increases of annual average precipitation will be 10 mm (for RCP2.6). Furthermore, the monthly long-term averages of Tmean and Tmax in all three scenarios show significant increases in summer. For precipitation, relative stability in summer, and increases in winter and early spring are predicted, but the changes in minimum temperature, relative humidity, and sunshine hours indicate relative stability.

Author(s):  
Sorush Niknamian

This research evaluated climate change impacts on temperature, precipitation, and runoff using LARS-WG and SWAT models under climate scenarios. First, drought intensity was calculated for the period 1987-2016. Then, the LARS-WG model was calibrated to generate climatological data for future periods. The coefficients of precipitation as well as minimum and maximum temperature changes were simulated as SWAT model inputs. The results of LARS-WG model indicated that temperature will increase in future periods and that changes will occur not only in precipitation rate but also in its pattern. Then, changes in runoff were simulated by introducing downscaled results to SWAT model. The model was calibrated and validated by SWAT-CUP software. Nash-Sutcliffe (NS) coefficients (0.58 and 0.49) and R2 determination coefficients (0.65 and 0.50) were obtained for calibration and validation periods, respectively. The results showed that runoff will increase in spring and summer during 2011-2030 period, but it will decrease in fall and winter. Further, runoff will rise in fall and winter while it will drop in spring and summer throughout 2046-2065 and 2080-2099 periods under all three scenarios. Such seasonal shifts in runoff levels result from climate change consequences in the forms of temperature rise, snowmelt, altered precipitation pattern, etc. Future-period evapotranspiration will rise under all three scenarios with a maximum increase in 2080-2099 period under A2 scenario. Additionally, rainfed crop yields will decline without considerable changes in irrigated and horticultural crop yields.


2021 ◽  
Author(s):  
Nagendra Reddy ◽  
Nagraj S Patil ◽  
Rajashekhar S Laddimath

Abstract The present study has been taken up to quantify the possible impacts of the climate change on the climate variables using the outputs of global climate models datasets over the Ghataprabha Sub-basin. The climate variables (precipitation, maximum and minimum temperature) data from the five selected global climate model dataset were downscaled using change factor method under four representative concentration pathway (RCP 2.6, 4.5, 6.0, and 8.5) scenarios for future periods near-century (2010-2039), mid-century (2040-2069), and end-century (2070-2099). The downscaled results of all the five models were ensembled using multi-model ensembling method to reduce the uncertainty in the projected results and the percentage change in the climate variables were shown with respect to the historical/baseline period (1961-1990) using spatial plots and histograms. The future projected results shows that percentage change in the annual mean precipitation with respect to the historical (1961-1990), is decreasing for most of the grids in the study area during the near-century while during mid and end centuries it shows an increasing trend across all the four RCP scenarios. The average daily minimum and maximum temperature with respect to the historical (1961-1990) values were showing an increasing trend in the study area during the near, mid, and end centuries across all the four RCP scenarios. Further, study also analysed the percentage change in 100-year return level over the study area.


Author(s):  
O. J. Kehinde ◽  
A. T. Adeboyejo

Susceptibility to ill health among aged people had been linked with climate change impacts in rapidly urbanising cities. Therefore, this study evaluates to the vulnerability of aged people to the health impacts of climate change in Ibadan, Nigeria. Data on clinically diagnosed climate related diseases (CRDs) (2000 – 2014) among aged people (>50 years) and temperature and rainfall parameters (1970 – 2007) in Ibadan were obtained and projected to year 2050. Also, the relationship between the climatic parameters and incidence of the five most prevalent CRDs were analysed using multiple regression. The increasing trend of mean maximum temperature (r = 0.47) and rainfall (r = 0.15) is associated with incidences of hypertension (34.4%), respiratory diseases (21.2%) and diarrhoea (14.3%) among aged people (> 60 years), mostly male folk (67.2%). The linear composite of disease communalities extracted 84.0% variance of the data set with the following component scores: skin disease (0.98), hypertension (0.96), respiratory disease (0.92), diarrhoea (0.89) and malaria (0.45). Further, CRDs (R2 = 27%, p = 0.012) in Ibadan among aged people could be significantly attributed to influences of climatic parameters. The study suggests building aged peoples’ resilience to emanating impacts through health and nutritional improvement programs, and re-introduction of neighbourhood parks and gardens.


2021 ◽  
Author(s):  
Simon Ricard ◽  
Philippe Lucas-Picher ◽  
François Anctil

Abstract. Statistical post-processing of climate model outputs is a common hydroclimatic modelling practice aiming to produce climate scenarios that better fit in-situ observations and to produce reliable stream flows forcing calibrated hydrologic models. Such practice is however criticized for disrupting the physical consistency between simulated climate variables and affecting the trends in climate change signals imbedded within raw climate simulations. It also requires abundant good-quality meteorological observations, which are not available for many regions in the world. A simplified hydroclimatic modelling workflow is proposed to quantify the impact of climate change on water discharge without resorting to meteorological observations, nor for statistical post-processing of climate model outputs, nor for calibrating hydrologic models. By combining asynchronous hydroclimatic modelling, an alternative framework designed to construct hydrologic scenarios without resorting to meteorological observations, and quantile perturbation applied to streamflow observations, the proposed workflow produces sound and plausible hydrologic scenarios considering: (1) they preserve trends and physical consistency between simulated climate variables, (2) are implemented from a modelling cascades despite observation scarcity, and (3) support the participation of end-users in producing and interpreting climate change impacts on water resources. The proposed modelling workflow is implemented over four subcatchments of the Chaudière River, Canada, using 9 North American CORDEX simulations and a pool of lumped conceptual hydrologic models. Forced with raw climate model outputs, hydrologic models are calibrated over the reference period according to a calibration metric designed to function with temporally uncorrelated observed and simulated streamflow values. Perturbation factors are defined by relating each simulated streamflow quantiles over both reference and future periods. Hydrologic scenarios are finally produced by applying perturbation factors to available streamflow observations.


2017 ◽  
Vol 189 ◽  
pp. 1-10 ◽  
Author(s):  
Mou Leong Tan ◽  
Ab Latif Ibrahim ◽  
Zulkifli Yusop ◽  
Vivien P. Chua ◽  
Ngai Weng Chan

2017 ◽  
Vol 114 (18) ◽  
pp. 4697-4702 ◽  
Author(s):  
Jasper A. Slingsby ◽  
Cory Merow ◽  
Matthew Aiello-Lammens ◽  
Nicky Allsopp ◽  
Stuart Hall ◽  
...  

Prolonged periods of extreme heat or drought in the first year after fire affect the resilience and diversity of fire-dependent ecosystems by inhibiting seed germination or increasing mortality of seedlings and resprouting individuals. This interaction between weather and fire is of growing concern as climate changes, particularly in systems subject to stand-replacing crown fires, such as most Mediterranean-type ecosystems. We examined the longest running set of permanent vegetation plots in the Fynbos of South Africa (44 y), finding a significant decline in the diversity of plots driven by increasingly severe postfire summer weather events (number of consecutive days with high temperatures and no rain) and legacy effects of historical woody alien plant densities 30 y after clearing. Species that resprout after fire and/or have graminoid or herb growth forms were particularly affected by postfire weather, whereas all species were sensitive to invasive plants. Observed differences in the response of functional types to extreme postfire weather could drive major shifts in ecosystem structure and function such as altered fire behavior, hydrology, and carbon storage. An estimated 0.5 °C increase in maximum temperature tolerance of the species sets unique to each survey further suggests selection for species adapted to hotter conditions. Taken together, our results show climate change impacts on biodiversity in the hyperdiverse Cape Floristic Region and demonstrate an important interaction between extreme weather and disturbance by fire that may make flammable ecosystems particularly sensitive to climate change.


2018 ◽  
Vol 3 (1) ◽  
pp. 53-66
Author(s):  
Pratiksha Sharma ◽  
Rishi Ram Kattel ◽  
Ananta Prakash Subedi

This paper reviews recent literature concerning effects of climate change on agriculture and its agricultural adaptation strategies, climate change impacts on Chepang communities and their maize farming. Climate change is perhaps the most serious environmental threat to agricultural productivity. Change in temperature and precipitation specially has greater influence on crop growth and productivity and most of these effect are found to be adverse. Climate change has been great global threat with global temperature rise by 0.83 °C and  global sea level rise by 0.19 m. Poor countries of the world are more vulnerable to changing climate due to different technological, institutional and resource constraints. In context of Nepal, practices like tree plantation, lowering numbers of livestock, shifting to off farm activities, sloping agricultural land technology (SALT) and shifting cultivation are most common coping strategies. Chepang, one of the most backward indigenous ethnic groups of Nepal are also found to perceive change in the climate. Perception  and adaptation strategies  followed by different farmers of world including Chepang  is mainly found to be effected by household head’s age, size of farm, family size, assessment to credit, information and extension service, training received and  transportation. Maize is second most important crop in Nepal in which increase in temperature is favorable in Mountain and its yield is negatively influenced by increase in summer rain and maximum temperature. Local knowledge of indigenous people provides new insights into the phenomenon that has not yet been scientifically researched. So, government should combine this perceptive with scientific climate scenario and should conduct activities in term of adoption strategies and policies to insist targeted and marginalized farmers.


2016 ◽  
Author(s):  
Dagnenet Fenta Mekonnen ◽  
Markus Disse

Abstract. Climate change is becoming one of the most arguable and threatening issues in terms of global context and their responses to environment and socio/economic drivers. Its direct impact becomes critical for water resource development and indirectly for agricultural production, environmental quality, economic development, social well-being. However, a large uncertainty between different Global Circulation Models (GCM) and downscaling methods exist that makes reliable conclusions for a sustainable water management difficult. In order to understand the future climate change of the Upper Blue Nile River Basin, two widely used statistical down scaling techniques namely LARS-WG and SDSM models were applied. Six CMIP3 GCMs for LARS-WG (CSIRO-MK3, ECHAM5-OM, MRI-CGCM2.3.2, HaDCM3, GFDL-CM2.1, CCSM3) model while HadCM3 GCM and canESM2 from CMIP5 GCMs for SDSM were used for climate change analysis. The downscaled precipitation results from the prediction of the six GCMs by LARS WG showed inconsistency and large inter model variability, two GCMs showed decreasing trend while 4 GCMs showed increasing in the range from −7.9 % to +43.7 % while the ensemble mean of the six GCM result showed increasing trend ranged from 1.0 % to 14.4 %. NCCCS GCM predicted maximum increase in mean annual precipitation. However, the projection from HadCM3 GCM is consistent with the multi-model average projection, which predicts precipitation increase from 1.7 % to 16.6 %. Conversely, the result from all GCMs showed a similar continuous increasing trend for maximum temperature (Tmax) and minimum temperature (Tmin) in all three future periods. The change for mean annual Tmax may increase from 0.4 °c to 4.3 °c whereas the change for mean annual Tmin may increase from 0.3 °c to 4.1 °c. Meanwhile, the result from SDSM showed an increasing trend for all three climate variables (precipitation, minimum and maximum temperature) from both HadCM3 and canESM2 GCMs. The relative change of mean annual precipitation range from 2.1 % to 43.8 % while the change for mean annual Tmax and Tmin may increase from 0.4 °c to 2.9 °c and from 0.3 °c to 1.6 °c respectively. The change in magnitude for precipitation is higher in RCP8.5 scenarios than others as expected. The present result illustrate that both down scaling techniques have shown comparable and good ability to simulate the current local climate variables which can be adopted for future climate change study with high confidence for the UBNRB. In order to see the comparative downscaling results from the two down scaling techniques, HadCM3 GCM of A2 scenario was used in common. The result obtained from the two down scaling models were found reasonably comparable and both approaches showed increasing trend for precipitation, Tmax and Tmin. However, the analysis of the downscaled climate data from the two techniques showed, LARS WG projected a relatively higher increase than SDSM.


Author(s):  
Mai Van Khiem

Abstract: This article presents the results of constructing climate change scenarios for Ho Chi Minh City (HCMC)based on the climate change scenarios of Vietnam published in 2016 by the Ministry of Natural Resources and Environment. Four high- resolution regional climate models include CCAM, clWRF, PRECIS, RegCM were used to downscale results of global climate models. The results show that the annual average temperature in HCMC tends to increase in the future compared to the baseline period 1986-2005, the increase depends on each RCP scenario. By the end of the century, the annual average temperature in HCMC had an increase of about 1.7÷1.9°C under the RCP4.5 scenario and 3.2÷3.6°C under RCP8.5.Meanwhile, annual rainfall in HCMC tends to increase in most periods under both of RCP scenarios. By the end of the century, annual rainfall in HCMC increases from 15% to 25% in the RCP4.5 scenario and 20-25% in the RCP8.5 scenario. Annual rainfall in coastal areas increases more than inland areas. Keyword: Climate change scenarios, Ho Chi Minh city


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