comments on "Sensitivity of future water availability projections to Global Climate Model, evapotranspiration estimation method, and greenhouse gas emission scenario" by Chang et al

2016 ◽  
Author(s):  
Anonymous
Keyword(s):  
Greenhouse Gas ◽  
Water Availability ◽  
Climate Model ◽  
Emission Scenario ◽  
Greenhouse Gas Emission ◽  
Global Climate ◽  
Global Climate Model ◽  
Estimation Method ◽  
Gas Emission ◽  
Evapotranspiration Estimation

scholarly journals Sensitivity of future water availability projections to Global Climate Model, evapotranspiration estimation method, and greenhouse gas emission scenario

2016 ◽  
Author(s):  
S. Chang ◽  
W. D. Graham ◽  
S. Hwang ◽  
R. Muñoz-Carpena
Keyword(s):  
Monte Carlo ◽  
Water Availability ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Estimation Method ◽  
Relative Sensitivity ◽  
Future Period ◽  
Future Projections ◽  
Period 2

Abstract. Projecting water availability under various possible future climate scenarios depends on the choice of Global Climate Model (GCM), evapotranspiration (ET) estimation method and Representative Concentration Pathway (RCP) trajectory. The relative contribution of each of these factors must be evaluated in order to choose an appropriate ensemble of future scenarios for water resources planning. In this study variance-based global sensitivity analysis and Monte Carlo filtering were used to evaluate the relative sensitivity of projected changes in precipitation (P), ET and water availability (defined here as P–ET) to choice of GCM, ET estimation method and RCP trajectory over the continental United States (US) for two distinct future periods: 2030–2060 (future period 1) and 2070–2100 (future period 2). A total of 9 GCMs, 10 ET methods and 3 RCP trajectories were used to quantify the range of future projections and estimate the relative sensitivity of future projections to each of these factors. In general, for all regions of the US, changes in future precipitation are most sensitive to the choice of GCM, while changes in future ET are most sensitive to the choice of ET estimation method. For changes in future water availability, the choice of GCM is the most influential factor in the cool season (December–March) and the choice of ET estimation method is most important in the warm season (May–October) for all regions except the South East US where GCM and ET have approximately equal influence throughout most of the year. Although the choice of RCP trajectory is generally less important than the choice of GCM or ET method, the impact of RCP trajectory increases in future period 2 over future period 1 for all factors. Monte Carlo filtering results indicate that particular GCMs and ET methods drive the projection of wetter or drier future conditions much more than RCP trajectory; however the set of GCMs and ET methods that produce wetter or drier projections varies substantially by region. Results of this study indicate that, in addition to using an ensemble of GCMs and several RCP trajectories, a range of regionally-relevant ET estimation methods should be used to develop a robust range of future conditions for water resource planning under climate change.

scholarly journals Species diversity of bats along an altitudinal gradient on Mount Mulanje, southern Malawi

2012 ◽  
Vol 28 (3) ◽  
pp. 243-253 ◽  
Author(s):  
Michael Curran ◽  
Mirjam Kopp ◽  
Jan Beck ◽  
Jakob Fahr
Keyword(s):  
Species Richness ◽  
Water Availability ◽  
Habitat Structure ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Large Degree ◽  
The Tropics ◽  
Bat Diversity ◽  
Local Habitat

Abstract:A climate model, based on effects of water availability and temperature, was recently proposed to explain global variation in bat species richness along altitudinal gradients. Yet such studies are sparse in the tropics and near-absent in Africa. Here we present results from an altitudinal study of bat diversity from Mount Mulanje, Malawi. Using ground nets, canopy nets and harp traps, we sampled eight sites across three habitat zones from 630 m to 2010 m asl. We assessed the influence of climatic, geographic and biotic variables on measures of estimated species richness, Fisher's α, and an unbiased index of compositional turnover. We recorded 723 individuals and 30 species along the gradient, revealing a ‘low plateau’ pattern in estimated species richness, peaking at 1220 m, which is congruent with the global climate model. Measures of local habitat structure significantly explained a large degree of variation in species richness and compositional turnover between sites. Fisher's α was further significantly correlated to mean annual relative humidity, suggesting a background climatic influence.

scholarly journals How aerosols and greenhouse gases influence the diurnal temperature range

2020 ◽  
Author(s):  
Camilla W. Stjern ◽  
Bjørn H. Samset ◽  
Olivier Boucher ◽  
Trond Iversen ◽  
Jean-François Lamarque ◽  
...  
Keyword(s):  
Global Warming ◽  
Greenhouse Gases ◽  
Greenhouse Gas ◽  
Diurnal Temperature Range ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Diurnal Temperature ◽  
Temperature Range ◽  
The Future

Abstract. The diurnal temperature range (DTR), or difference between the maximum and minimum temperature within one day, is one of many climate parameters that affects health, agriculture and society. Understanding how DTR evolves under global warming is therefore crucial. Since physically different drivers of climate change, such as greenhouse gases and aerosols, have distinct influences on global and regional climate, predicting the future evolution of DTR requires knowledge of the effects of individual climate forcers, as well as of the future emissions mix, in particular in high emission regions. Using global climate model simulations from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP), we investigate how idealized changes in the atmospheric levels of a greenhouse gas (CO2) and aerosols (black carbon and sulfate) influence DTR, globally and in selected regions. We find broad geographical patterns of annual mean change that are similar between climate drivers, pointing to a generalized response to global warming which is not defined by the individual forcing agents. Seasonal and regional differences, however, are substantial, which highlights the potential importance of local background conditions and feedbacks. While differences in DTR responses among drivers are minor in Europe and North America, there are distinctly different DTR responses to aerosols and greenhouse gas perturbations over India and China, where present aerosol emissions are particularly high. BC induces substantial reductions in DTR, which we attribute to strong modelled BC-induced cloud responses in these regions.

scholarly journals Changes in length of rainy season and rainfall extremes under moderate greenhouse gas emission scenario in the Vea catchment, Ghana

2021 ◽  
Author(s):  
Isaac Larbi ◽  
Bessah Enoch ◽  
Clement Nyamekye ◽  
Joshua Amuzu ◽  
Gloria C. Okafor ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Rainy Season ◽  
Rainfall Intensity ◽  
Emission Scenario ◽  
Greenhouse Gas Emission ◽  
Early Warning Systems ◽  
Annual Rainfall ◽  
Gas Emission ◽  
Rainfall Extremes ◽  
Projected Changes

Abstract The economic implications of extreme climate changes are found to impact sub-Saharan Africa negatively. This study aimed to analyze projected changes in length of rainy season (LRS), and rainfall extreme indices at the Vea catchment, Ghana. The analysis was performed using high-resolution simulated rainfall data from Weather Research and Forecasting (WRF) model under moderate greenhouse gas emission scenario for the period 2020–2049 relative to 1981–2010 period. LRS was computed from the difference between rainfall onset and cessation dates, and its trends were assessed using Mann–Kendall test and Sen's slope estimator. Annual rainfall intensity and frequency indices were computed. Results showed an increase in mean LRS from 168 to 177 days, which was at a rate of 1 day/year in the future (2020–2049). The LRS increase would be more significant at northern and south-western parts of the catchment. Rainfall intensity and frequency indices are projected to increase at spatial scale across the catchment. Projected changes in rainfall extremes could increase the frequency and intensity of drought and flood events. Thus, it is necessary to integrate suitable climate change adaptation measures such as rainwater harvesting, flood control measures, and development of early warning systems in the planning process by decision-makers at the catchment.

scholarly journals California Drought Outlooks Based on Climate Change Models’ Effects on Water Availability

Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3211
Author(s):  
Lauren Lynam ◽  
Thomas Piechota
Keyword(s):  
Water Availability ◽  
Climate Model ◽  
Greenhouse Gas Emission ◽  
Historical Record ◽  
Historical Period ◽  
Climate Projections ◽  
Gas Emission ◽  
Rcp Scenarios ◽  
Change Models ◽  
Rcp 8.5

Future streamflow in California is evaluated based on eight climate projections models and the effects on water availability. The unimpaired projected streamflow for eleven California rivers, collected from Cal-Adapt, are compared with unimpaired historical flows (1950–2015) using eight climate model projections (2020–2099) identified as representative as possible future scenarios; Warm Dry RCP 4.5, Average RCP 4.5, Cool Wet RCP 4.5, Other RCP 4.5, Warm Dry RCP 8.5, Average RCP 8.5, Cool Wet RCP 8.5, and Other RCP 8.5. Projected drought deficits (or magnitudes), durations, and intensities are statistically tested against historical values to determine significance of differences between past streamflow and future streamflow. The models show significant differences between historical and projected streamflow with all three drought categories (deficit, duration, intensity), using difference in means t-tests. Warm Dry and Other simulations are projected to have larger droughts (2–3 times larger) than the historical record. Average and Cool Wet simulations are projected to have fewer droughts than the historical period. Results are consistent for 4.5 and 8.5 RCP scenarios that represent two different greenhouse gas emission levels. Potential impacts of such streamflow variations are discussed.

scholarly journals Projecting flood hazard under climate change: an alternative approach to model chains

2013 ◽  
Vol 1 (6) ◽  
pp. 7357-7385 ◽  
Author(s):  
J. M. Delgado ◽  
B. Merz ◽  
H. Apel
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Climate Model ◽  
Emission Scenario ◽  
Flood Hazard ◽  
Global Climate ◽  
Global Climate Model ◽  
Flood Frequency ◽  
Frequency Model ◽  
Alternative Approach

Abstract. Flood hazard projections under climate change are typically derived by applying model chains consisting of the following elements: "emission scenario – global climate model – downscaling, possibly including bias correction – hydrological model – flood frequency analysis". To date, this approach yields very uncertain results, due to the difficulties of global and regional climate models to represent precipitation. The implementation of such model chains requires large efforts, and their complexity is high. We propose for the Mekong River an alternative approach which is based on a shortened model chain: "emission scenario – global climate model – non-stationary flood frequency model". The underlying idea is to use a link between the Western Pacific monsoon and local flood characteristics: the variance of the monsoon drives a nonstationary flood frequency model, yielding a direct estimate of flood probabilities. This approach bypasses the uncertain precipitation, since the monsoon variance is derived from large-scale wind fields which are better represented by climate models. The simplicity of the monsoon-flood link allows deriving large ensembles of flood projections under climate change. We conclude that this is a worthwhile, complementary approach to the typical model chains in catchments where a substantial link between climate and floods is found.

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