scholarly journals Assessment of CMIP5 Models over North Pakistan for Quantification of Climate Change Impacts on Future Hydrology

2020 ◽  
Author(s):  
Rida Sehar Kiani ◽  
Abida Farooqi ◽  
Shaukat Ali ◽  
Firdos Khan
Keyword(s):  
Climate Change ◽  
Climate Change Impacts ◽  
Cmip5 Models ◽  
North Pakistan

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

2020 ◽  
Author(s):  
Hossein Shakeri ◽  
Homayoun Motiee ◽  
Edward McBean
Keyword(s):  
Climate Change ◽  
Relative Stability ◽  
Climate Change Impacts ◽  
Maximum Temperature ◽  
Cmip5 Models ◽  
Climate Variables ◽  
Annual Average ◽  
Maximum Increase ◽  
Rcp Scenarios ◽  
Large Cities

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.

scholarly journals Climate change impacts on net primary production (NPP) and export production (EP) regulated by increasing stratification and phytoplankton community structure in CMIP5 models

2015 ◽  
Vol 12 (15) ◽  
pp. 12851-12897 ◽  
Author(s):  
W. Fu ◽  
J. Randerson ◽  
J. K. Moore
Keyword(s):  
Climate Change ◽  
Community Structure ◽  
Primary Production ◽  
Phytoplankton Community ◽  
Net Primary Production ◽  
Climate Change Impacts ◽  
Climate Impacts ◽  
Cmip5 Models ◽  
Phytoplankton Community Structure ◽  
Rcp 8.5

Abstract. We examine climate change impacts on net primary production (NPP) and export production (sinking particulate flux; EP) with simulations from nine Earth System Models (ESMs) performed in the framework of the fifth Coupled Model Inter-comparison Project (CMIP5). Global NPP and EP are reduced considerably by the end of the century for the intense warming scenario of Representative Concentration Pathway (RCP) 8.5. Relative to the 1990s, global NPP in the 2090s is reduced by 2.3–16 % and EP by 7–18 %. The models with the largest increases in stratification (and largest relative reductions in NPP and EP) also show the largest positive biases in stratification for the contemporary period, suggesting some potential overestimation of climate impacts on NPP and EP. All of the CMIP5 models show an increase in stratification in response to surface ocean warming and freshening that is accompanied by decreases in NPP, EP, and surface macronutrient concentrations. There is considerable variability across models in the absolute magnitude of these fluxes, surface nutrient concentrations, and their perturbations by climate change, indicating large model uncertainties. The negative response of NPP and EP to stratification increases reflects a bottom-up control, as nutrient flux to the euphotic zone declines. Models with dynamic phytoplankton community structure show larger declines in EP than in NPP. This is driven by phytoplankton community composition shifts, with a reduced percentage of NPP by large phytoplankton under RCP 8.5, as smaller phytoplankton are favored under the increasing nutrient stress. Thus, projections of the NPP response to climate change in the CMIP5 models are critically dependent on the simulated phytoplankton community structure, the efficiency of the biological pump, and the resulting (highly variable) levels of regenerated production. Community composition is represented relatively simply in the CMIP5 models, and should be expanded to better capture the spatial patterns and the changes in export efficiency that are necessary for predicting climate impacts on NPP.

scholarly journals Climate Change Impacts on Yangtze River Discharge at the Three Gorges Dam

2016 ◽  
Author(s):  
Steve J. Birkinshaw ◽  
Selma B. Guerreiro ◽  
Alex Nicholson ◽  
Qiuhua Liang ◽  
Paul Quinn ◽  
...  
Keyword(s):  
Climate Change ◽  
River Discharge ◽  
Yangtze River ◽  
Climate Change Impacts ◽  
Cmip5 Models ◽  
Three Gorges ◽  
The Yangtze River ◽  
The Three Gorges ◽  
Projected Changes ◽  
The Three Gorges Dam

Abstract. The Yangtze River Basin is home to more than 400 million people, contributes to nearly half of China’s food production, and is susceptible to major floods. Therefore planning for climate change impacts on river discharges is essential. We used a physically-based distributed hydrological model, Shetran, to simulate discharge in the Yangtze River just below the Three Gorges Dam at Yichang (1,007,200 km2), obtaining an excellent match between simulated and measured daily discharge, with Nash-Sutcliffe efficiencies of 0.95 for the calibration period (1996–2000) and 0.92 for the validation period (2001–2005). We then used a simple monthly delta change approach for 78 climate model projections (35 different GCMs) from the Coupled Model Intercomparison Project-5 (CMIP5) to examine the effect of climate change on river discharge for 2041–2070 for Representative Concentration Pathway 8.5. Projected changes to the basin’s annual precipitation varied between −3.6 % and +14.8 % but increases in temperature and consequently evapotranspiration (calculated using the Thornthwaite equation) were projected by all CMIP5 models, resulting in projected changes in the basin’s annual discharge from −29.8 % to +16.0 %. These large differences were mainly due to the predicted expansion of the summer monsoon north and west into the Yangtze basin in some CMIP5 models, e.g. CanESM2, but not in others, e.g. CSIRO-Mk3-6-0. This was despite both models being able to simulate current climate well. Until projections of the strength and location of the monsoon under a future climate improve there will remain large uncertainties in the direction and magnitude of future change in discharge for the Yangtze.

scholarly journals Climate change impacts on net primary production (NPP) and export production (EP) regulated by increasing stratification and phytoplankton community structure in the CMIP5 models

2016 ◽  
Vol 13 (18) ◽  
pp. 5151-5170 ◽  
Author(s):  
Weiwei Fu ◽  
James T. Randerson ◽  
J. Keith Moore
Keyword(s):  
Climate Change ◽  
Community Structure ◽  
Primary Production ◽  
Phytoplankton Community ◽  
Net Primary Production ◽  
Climate Change Impacts ◽  
Cmip5 Models ◽  
Nutrient Concentrations ◽  
Phytoplankton Community Structure ◽  
Export Production

Abstract. We examine climate change impacts on net primary production (NPP) and export production (sinking particulate flux; EP) with simulations from nine Earth system models (ESMs) performed in the framework of the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Global NPP and EP are reduced by the end of the century for the intense warming scenario of Representative Concentration Pathway (RCP) 8.5. Relative to the 1990s, NPP in the 2090s is reduced by 2–16 % and EP by 7–18 %. The models with the largest increases in stratification (and largest relative declines in NPP and EP) also show the largest positive biases in stratification for the contemporary period, suggesting overestimation of climate change impacts on NPP and EP. All of the CMIP5 models show an increase in stratification in response to surface–ocean warming and freshening, which is accompanied by decreases in surface nutrients, NPP and EP. There is considerable variability across the models in the magnitudes of NPP, EP, surface nutrient concentrations and their perturbations by climate change. The negative response of NPP and EP to increasing stratification reflects primarily a bottom-up control, as upward nutrient flux declines at the global scale. Models with dynamic phytoplankton community structure show larger declines in EP than in NPP. This pattern is driven by phytoplankton community composition shifts, with reductions in productivity by large phytoplankton as smaller phytoplankton (which export less efficiently) are favored under the increasing nutrient stress. Thus, the projections of the NPP response to climate change are critically dependent on the simulated phytoplankton community structure, the efficiency of the biological pump and the resulting levels of regenerated production, which vary widely across the models. Community structure is represented simply in the CMIP5 models, and should be expanded to better capture the spatial patterns and climate-driven changes in export efficiency.

scholarly journals Extreme precipitation and temperature events in the past decades and its future impacts in the São Paulo Macro Metropolis.

2021 ◽  
Author(s):  
Thamiris Luisa de Oliveira Brandão Campos ◽  
Edmilson Dias de Freitas
Keyword(s):  
Climate Change ◽  
Extreme Events ◽  
Extreme Precipitation ◽  
Urban Areas ◽  
Climate Change Impacts ◽  
South Atlantic Convergence Zone ◽  
Urban Heat Islands ◽  
Cmip5 Models ◽  
North Coast ◽  
Precipitation And Temperature

<p>The São Paulo Macro Metropolis (SPMM) is composed of five metropolitan regions (i.e., São Paulo, Campinas, Paraíba Valley and North Coast, Sorocaba, and Santos), two urban agglomerations (i.e., Piracicaba and Jundiaí) and a microregion of Bragança. With an estimated 33 million inhabitants over an area 53,000 km<sup>2</sup>. Urban areas take up 11,000 km<sup>2</sup> of this area, represented by 174 municipalities that account for nearly 73.9% of the state’s total population. The SPMM is already experiencing the impacts of severe climate events. It is situated along a transition climatic region between humid subtropical and tropical climates. Meteorological systems such as cold fronts, the South Atlantic Convergence Zone (ZCAS), sea breezes, urban heat islands, and other local circulations associated with topography favor the occurrence of severe weather at different time scales. The study aims at understanding climate change effects on the intensity and frequency of temperature and precipitation extremes in the SPMM, contributing to the establishment of policies to reduce the existing socioenvironmental risks in urban areas. For this, the ability of observation systems, reanalysis (ERA5, ERA40, NCEP/NCAR, and Terra Climate), and remote sensing (CMAP and CPC) were analyzed and used to show the decadal evolution of extreme events in SPMM. We also investigated the potential of CMIP5 models to simulate the extreme precipitation and temperature events in the SPMM that occurred between the 1950s and 2005. Future climate changes in the SPMM were analyzed based on CMIP5 models that best simulate past extreme events in the SPMM, considering the different carbon emission scenarios. This study is important to develop adaptive strategies to deal with climate change impacts on urban areas, such as droughts and floods.</p>

scholarly journals Projected climate change impacts on North Sea and Baltic Sea: CMIP3 and CMIP5 model based scenarios

2015 ◽  
Vol 12 (15) ◽  
pp. 12229-12279 ◽  
Author(s):  
D. Pushpadas ◽  
C. Schrum ◽  
U. Daewel
Keyword(s):  
Climate Change ◽  
Primary Production ◽  
Baltic Sea ◽  
North Sea ◽  
Climate Change Impacts ◽  
Cmip5 Models ◽  
The North ◽  
The North Sea ◽  
The Baltic ◽  
Projected Changes

Abstract. Climate change impacts on the marine biogeochemistry and lower trophic level dynamics in the North Sea and Baltic Sea have been assessed using regional downscaling in a number of recent studies. However, most of these where only forced by physical conditions from Global Climate Models (GCMs) and regional downscaling considering the climate change impact on oceanic nutrient conditions from Global Earth System Models (ESMs) are rare and so far solely based on CMIP3-generation climate models. The few studies published show a large range in projected future primary production and hydrodynamic condition. With the addition of CMIP5 models and scenarios, the demand to explore the uncertainty in regional climate change projections increased. Moreover, the question arises how projections based on CMIP5-generation models compare to earlier projections and multi-model ensembles comprising both AR4 and AR5 generation forcing models. Here, we investigated the potential future climate change impacts to the North Sea and the Baltic Sea ecosystem using a coherent regional downscaling strategy based on the regional coupled bio-physical model ECOSMO. ECOSMO was forced by output from different ESMs from both CMIP3 and CMIP5 models. Multi-model ensembles using CMIP3/A1B and CMIP5/RCP4.5 scenarios are examined, where the selected CMIP5 models are the successors of the chosen CMIP3 models. Comparing projected changes with the present day reference condition, all these simulations predicted an increase in Sea Surface Temperature (SST) in both North Sea and Baltic Sea, reduction in sea ice in the Baltic, decrease in primary production in the North Sea and an increase in primary production in the Baltic Sea. Despite these largely consistent results on the direction of the projected changes, our results revealed a broad range in the amplitude of projected climate change impacts. Our study strengthens the claim that the choice of the ESM is a major factor for regional climate projections. The change in oceanic nutrient input appeared to be the major driver for the projected changes in North Sea primary production. Assessing the spread in ensemble groups, we found that there is for the North Sea a significant reduction in the spread of projected changes among CMIP5 forced model simulations compared to those forced by CMIP3 ESMs, except for salinity. The latter was due to an unexpected salinification observed in one of the CMIP5 model while all other models exhibit freshening in the future. However, for the Baltic Sea substantial differences in inter-model variability in projected climate change impact to primary production is lacking.

Climate change impacts on water demand and availability using CMIP5 models in the Jaguaribe basin, semi-arid Brazil

2018 ◽  
Vol 77 (15) ◽  
Author(s):  
Rubens Gondim ◽  
Cleiton Silveira ◽  
Francisco de Souza Filho ◽  
Francisco Vasconcelos ◽  
Daniel Cid
Keyword(s):  
Climate Change ◽  
Water Demand ◽  
Climate Change Impacts ◽  
Cmip5 Models ◽  
Semi Arid

scholarly journals Climate change impacts on Yangtze River discharge at the Three Gorges Dam

2017 ◽  
Vol 21 (4) ◽  
pp. 1911-1927 ◽  
Author(s):  
Steve J. Birkinshaw ◽  
Selma B. Guerreiro ◽  
Alex Nicholson ◽  
Qiuhua Liang ◽  
Paul Quinn ◽  
...  
Keyword(s):  
Climate Change ◽  
River Discharge ◽  
Yangtze River ◽  
Climate Change Impacts ◽  
Cmip5 Models ◽  
Three Gorges ◽  
The Yangtze River ◽  
The Three Gorges ◽  
Projected Changes ◽  
The Three Gorges Dam

Abstract. The Yangtze River basin is home to more than 400 million people and contributes to nearly half of China's food production. Therefore, planning for climate change impacts on water resource discharges is essential. We used a physically based distributed hydrological model, Shetran, to simulate discharge in the Yangtze River just below the Three Gorges Dam at Yichang (1 007 200 km2), obtaining an excellent match between simulated and measured daily discharge, with Nash–Sutcliffe efficiencies of 0.95 for the calibration period (1996–2000) and 0.92 for the validation period (2001–2005). We then used a simple monthly delta change approach for 78 climate model projections (35 different general circulation models – GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to examine the effect of climate change on river discharge for 2041–2070 for Representative Concentration Pathway 8.5. Projected changes to the basin's annual precipitation varied between −3.6 and +14.8 % but increases in temperature and consequently evapotranspiration (calculated using the Thornthwaite equation) were projected by all CMIP5 models, resulting in projected changes in the basin's annual discharge from −29.8 to +16.0 %. These large differences were mainly due to the predicted expansion of the summer monsoon north and west into the Yangtze Basin in some CMIP5 models, e.g. CanESM2, but not in others, e.g. CSIRO-Mk3-6-0. This was despite both models being able to simulate current climate well. Until projections of the strength and location of the monsoon under a future climate improve, large uncertainties in the direction and magnitude of future change in discharge for the Yangtze will remain.

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