5 research outputs found
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Projected impacts on heat-related mortality from changes in the mean and variability of temperature with climate change
The aim of this paper is to demonstrate the importance of changing temperature variability
with climate change in assessments of future heat-related mortality. Previous studies have only considered
changes in the mean temperature. Here we present estimates of heat-related mortality resulting from climate
change for six cities: Boston, Budapest, Dallas, Lisbon, London and Sydney. They are based on climate
change scenarios for the 2080s (2070-2099) and the temperature-mortality (t-m) models constructed and
validated in Gosling et al. (2007). We propose a novel methodology for assessing the impacts of climate
change on heat-related mortality that considers both changes in the mean and variability of the temperature
distribution
Understanding each other's models: a standard representation of global water models to support improvement, intercomparison, and communication
Global water models (GWMs) simulate the terrestrial water cycle, on the global scale, and are used to assess the impacts of climate change on freshwater systems. GWMs are developed within different modeling frameworks and consider different underlying hydrological processes, leading to varied model structures. Furthermore, the equations used to describe various processes take different forms and are generally accessible only from within the individual model codes. These factors have hindered a holistic and detailed understanding of how different models operate, yet such an understanding is crucial for explaining the results of model evaluation studies, understanding inter-model differences in their simulations, and identifying areas for future model development. This study provides a comprehensive overview of how state-of-the-art GWMs are designed. We analyze water storage compartments, water flows, and human water use sectors included in 16 GWMs that provide simulations for the Inter-Sectoral Impact Model Intercomparison Project phase 2b (ISIMIP2b). We develop a standard writing style for the model equations to further enhance model improvement, intercomparison, and communication. In this study, WaterGAP2 used the highest number of water storage compartments, 11, and CWatM used 10 compartments. Seven models used six compartments, while three models (JULES-W1, Mac-PDM.20, and VIC) used the lowest number, three compartments. WaterGAP2 simulates five human water use sectors, while four models (CLM4.5, CLM5.0, LPJmL, and MPI-HM) simulate only water used by humans for the irrigation sector. We conclude that even though hydrologic processes are often based on similar equations, in the end, these equations have been adjusted or have used different values for specific parameters or specific variables. Our results highlight that the predictive uncertainty of GWMs can be reduced through improvements of the existing hydrologic processes, implementation of new processes in the models, and high-quality input data
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Climate change and heat-related mortality in six cities Part 2: climate model evaluation and projected impacts from changes in the mean and variability of temperature with climate change
Previous assessments of the impacts of climate
change on heat-related mortality use the "delta method" to
create temperature projection time series that are applied to
temperature-mortality models to estimate future mortality
impacts. The delta method means that climate model bias in
the modelled present does not influence the temperature
projection time series and impacts. However, the delta
method assumes that climate change will result only in a
change in the mean temperature but there is evidence that
there will also be changes in the variability of temperature
with climate change. The aim of this paper is to demonstrate
the importance of considering changes in temperature
variability with climate change in impacts assessments of
future heat-related mortality. We investigate future heatrelated
mortality impacts in six cities (Boston, Budapest,
Dallas, Lisbon, London and Sydney) by applying temperature
projections from the UK Meteorological Office
HadCM3 climate model to the temperature-mortality models
constructed and validated in Part 1. We investigate the
impacts for four cases based on various combinations of
mean and variability changes in temperature with climate
change. The results demonstrate that higher mortality is
attributed to increases in the mean and variability of temperature
with climate change rather than with the change in
mean temperature alone. This has implications for interpreting
existing impacts estimates that have used the delta
method. We present a novel method for the creation of
temperature projection time series that includes changes in
the mean and variability of temperature with climate change
and is not influenced by climate model bias in the modelled
present. The method should be useful for future impacts
assessments. Few studies consider the implications that the
limitations of the climate model may have on the heatrelated
mortality impacts. Here, we demonstrate the
importance of considering this by conducting an evaluation
of the daily and extreme temperatures from HadCM3,
which demonstrates that the estimates of future heat-related
mortality for Dallas and Lisbon may be overestimated due
to positive climate model bias. Likewise, estimates for
Boston and London may be underestimated due to negative
climate model bias. Finally, we briefly consider uncertainties
in the impacts associated with greenhouse gas
emissions and acclimatisation. The uncertainties in the
mortality impacts due to different emissions scenarios of
greenhouse gases in the future varied considerably by
location. Allowing for acclimatisation to an extra 2°C in
mean temperatures reduced future heat-related mortality by
approximately half that of no acclimatisation in each city
Understanding each other's models An introduction and a standard representation of 16 global water models to support intercomparison, improvement, and communication
Global water models (GWMs) simulate the terrestrial water cycle on the global scale and are used to assess the impacts of climate change on freshwater systems. GWMs are developed within different modelling frameworks and consider different underlying hydrological processes, leading to varied model structures. Furthermore, the equations used to describe various processes take different forms and are generally accessible only from within the individual model codes. These factors have hindered a holistic and detailed understanding of how different models operate, yet such an understanding is crucial for explaining the results of model evaluation studies, understanding inter-model differences in their simulations, and identifying areas for future model development. This study provides a comprehensive overview of how 16 state-of-the-art GWMs are designed. We analyse water storage compartments, water flows, and human water use sectors included in models that provide simulations for the Inter-Sectoral Impact Model Intercomparison Project phase 2b (ISIMIP2b). We develop a standard writing style for the model equations to enhance model intercomparison, improvement, and communication. In this study, WaterGAP2 used the highest number of water storage compartments, 11, and CWatM used 10 compartments. Six models used six compartments, while four models (DBH, JULES-W1, Mac-PDM.20, and VIC) used the lowest number, three compartments. WaterGAP2 simulates five human water use sectors, while four models (CLM4.5, CLM5.0, LPJmL, and MPI-HM) simulate only water for the irrigation sector. We conclude that, even though hydrological processes are often based on similar equations for various processes, in the end these equations have been adjusted or models have used different values for specific parameters or specific variables. The similarities and differences found among the models analysed in this study are expected to enable us to reduce the uncertainty in multi-model ensembles, improve existing hydrological processes, and integrate new processes
Understanding each other's models: an introduction and a standard representation of 16 global water models to support intercomparison, improvement, and communication
International audienceAbstract. Global water models (GWMs) simulate the terrestrial water cycle on the global scale and are used to assess the impacts of climate change on freshwater systems. GWMs are developed within different modelling frameworks and consider different underlying hydrological processes, leading to varied model structures. Furthermore, the equations used to describe various processes take different forms and are generally accessible only from within the individual model codes. These factors have hindered a holistic and detailed understanding of how different models operate, yet such an understanding is crucial for explaining the results of model evaluation studies, understanding inter-model differences in their simulations, and identifying areas for future model development. This study provides a comprehensive overview of how 16 state-of-the-art GWMs are designed. We analyse water storage compartments, water flows, and human water use sectors included in models that provide simulations for the Inter-Sectoral Impact Model Intercomparison Project phase 2b (ISIMIP2b). We develop a standard writing style for the model equations to enhance model intercomparison, improvement, and communication. In this study, WaterGAP2 used the highest number of water storage compartments, 11, and CWatM used 10 compartments. Six models used six compartments, while four models (DBH, JULES-W1, Mac-PDM.20, and VIC) used the lowest number, three compartments. WaterGAP2 simulates five human water use sectors, while four models (CLM4.5, CLM5.0, LPJmL, and MPI-HM) simulate only water for the irrigation sector. We conclude that, even though hydrological processes are often based on similar equations for various processes, in the end these equations have been adjusted or models have used different values for specific parameters or specific variables. The similarities and differences found among the models analysed in this study are expected to enable us to reduce the uncertainty in multi-model ensembles, improve existing hydrological processes, and integrate new processes