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In recent years, research on climate change and human security has received much attention among policy makers and academia alike. Communities in the Global South that rely on an intact resource base will especially be affected by predicted changes in temperature and precipitation. The objective of this article is to better understand under what conditions local communities can adapt to anticipated impacts of climate change and avoid conflict over the loss of resources. The empirical part of the paper answers the question to what extent local communities in the Chilwa Basin in Malawi have experienced climate change and how they are affected by it. Further, it assesses one of Malawi's adaptation projects designed to build resilience to a warmer and more variable climate, and points to some of its limitations. This research shows that not all adaptation strategies are suited to cope with a warmer and more variable climate. [ABSTRACT FROM AUTHOR]

Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. Currently, two such levels are discussed in the context of the international climate negotiations as long-term global temperature goals: a below 2 °C and a 1.5 °C limit in global-mean temperature rise above pre-industrial levels. Despite the prominence of these two temperature limits, a comprehensive assessment of the differences in climate impacts at these levels is still missing. Here we provide an assessment of key impacts of climate change at warming levels of 1.5 °C and 2 °C, including extreme weather events, water availability, agricultural yields, sea-level rise and risk of coral reef loss. Our results reveal substantial differences in impacts between 1.5 °C and 2 °C. For heat-related extremes, the additional 0.5 °C increase in global-mean temperature marks the difference between events at the upper limit of present-day natural variability and a new climate regime, particularly in tropical regions. Similarly, this warming difference is likely to be decisive for the future of tropical coral reefs. In a scenario with an end-of-century warming of 2 °C, virtually all tropical coral reefs are projected to be at risk of severe degradation due to temperature induced bleaching from 2050 onwards. This fraction is reduced to about 90 % in 2050 and projected to decline to 70 % by 2100 for a 1.5 °C scenario. Analyses of precipitation-related impacts reveal distinct regional differences and several hot-spots of change emerge. Regional reduction in median water availability for the Mediterranean is found to nearly double from 9 to 17 % between 1.5 °C and 2 °C, and the projected lengthening of regional dry spells increases from 7 % longer to 11 %. Projections for agricultural yields differ between crop types as well as world regions. While some (in particular high-latitude) regions may benefit, tropical regions like West Africa, South-East Asia, as well as Central and Northern South America are projected to face local yield reductions, particularly for wheat and maize. Best estimate sea-level rise projections based on two illustrative scenarios indicate a 50 cm rise by 2100 relative to year 2000-levels under a 2 °C warming, which is about 10 cm lower for a 1.5 °C scenario. Our findings highlight the importance of regional differentiation to assess future climate risks as well as different vulnerabilities to incremental increases in global-mean temperature. The article provides a consistent and comprehensive assessment of existing projections and a solid foundation for future work on refining our understanding of warming-level dependent climate impacts. [ABSTRACT FROM AUTHOR]

The article presents a newly composed dataset of climate change scenario to pacify requirements for global assessments of climate change impacts. It is evident that global mean temperature change has become the yardstick to gauze impact of unavoidable climate change and requirement of adaptation. It is informed that the dataset helps in analyzing impact of climate change and implement climate model.

Instrumental data from the pre–Industrial Revolution period are important to -understand climate change. In this paper, the observations made by the French missionary J. Amiot in present-day central Beijing during 1757–62 were processed and analyzed. The observations represent the earliest continuous dataset of meteorological records found in China that have been digitized recently. Comparisons between the Amiot annual temperature range and extreme values with modern observations showed that the observations were read at approximately 0800 and 1500 local solar time (LST) in a well-ventilated outdoor site. The daily maximum, minimum, and mean temperatures (T-max, T-min, and T-mean, respectively) during 1757–62 were determined by examining the relationship between temperature at 0800 and 1500 LST and T-max, T-min, and T-mean in modern reference series. Nearly 260 years ago, Beijing's climate was typical of an inland temperate monsoon zone with annual T-mean, annual mean T-max, and annual mean T-min being 11.5°, 17.8°, and 6.1°C, respectively; further, the temperatures did not vary considerably from the 1951–1980 temperatures, but differed evidently compared to relatively recent decades (1981–2020). The difference was larger than the magnitudes of global and regional temperature changes. Thus, climate warming since the pre–Industrial Revolution period in the urban areas of Beijing has dominantly occurred over the last four decades. Uncertainties related to the thermometer and observational conditions 260 years ago and the interpolation method used have also been discussed in this paper. [ABSTRACT FROM AUTHOR]

This paper examines efforts taking place in London, San Francisco and Stockholm to implement deep greenhouse gas emission cuts--'deep decarbonization'--through the transformation of buildings and urban energy infrastructure for increased energy efficiency and low/zero carbon energy supply. Drawing on interviews, policy document analysis, and site tours to buildings and energy infrastructure, this paper analyzes how deep decarbonization is being embedded into urban buildings, energy systems, and institutions. It argues that practitioners are finding ways to create new low/zero carbon future buildings, but are having difficulty correcting the historical development path through retrofitting. This paper examines solutions and challenges brought to light by urban decarbonization in practice targeting existing buildings from which other cities can learn. Four key lessons for low/zero carbon retrofits are highlighted: 1) shift primary targets from homeowners to owners of multiple buildings, 2) expand the suite of resources available to support zero carbon retrofits, 3) experiment and teach using public investment, and 4) institutionalize energy and carbon reporting linked to municipal department targets. Given the necessity of low-carbon, efficient, and climate-resilient building retrofits to address the climate crisis, action can be scaled up by considering buildings and energy infrastructure an infrastructure priority for public investment. Keywords: urban; cities; climate change; decarbonization Cet article examine les efforts deployes a Londres, San Francisco et Stockholm pour mettre en place une reduction profonde des emissions de gaz a effet de serre--<>--par la transformation des batiments et des infrastructures energetiques urbaines pour l'efficacite energetique et l'approvisionnement d'energie a zero ou faible intensite carbone. S'appuyant sur des entretiens, l'analyse de documents de politiques publiques et des visites de sites d'immeubles et d'infrastructures energetiques, cet article analyse comment la decarbonisation en profondeur est incorporee dans les batiments urbains, les systemes energetiques et les institutions. Il fait valoir que les praticiens trouvent des moyens de creer de nouveaux developpements a zero ou faibles emissions de carbone, mais ceux-ci ont du mal a corriger la trajectoire historique de developpement avec l'amelioration energetique. Cet article examine les solutions et les defis mis en evidence par la pratique de la decarbonisation urbaine qui cible les batiments existants, a partir desquels d'autres villes peuvent apprendre. Quatre lecons principales pour la renovation a faibles emissions ou carboneutre sont soulignees: 1) transferer les objectifs principaux des proprietaries aux proprietaries de plusieurs batiments, 2) elargir la gamme de ressources disponibles pour soutenir les ameliorations de la reduction des emissions de carbone, 3) experimenter et enseigner en utilisant les investissements publics et 4) institutionnaliser les rapports sur l'energie et le carbone lies aux objectifs des services municipaux. Compte tenu de la necessite de renover les batiments dans une optique de sobriete carbone, d'efficacite et de resilience face a la crise climatique, il est suggere d'intensifier l'action en considerant les batiments et les infrastructures energetiques comme une priorite pour les investissements publics dans les infrastructures. Mots cles: urbain; villes; changement climatique; decarbonisation, Introduction It is increasingly clear that urban climate change mitigation features diverse and multi-level action driven by actors from across government, industry and non-profit sectors. In this context, a number [...]

The phenomenon of global warming is raising concerns in the U.S. and abroad as scientific studies report that potentially costly climate changes are to take place. For the U.S. in particular, it is expected that the 2008 presidential elections will shift the U.S. approach to global warming. Using externality theory, public goods, and game theory, this paper provides a theoretical, economic analysis of different responses to global warming. It concludes that a science and technology based market strategy is superior to a regulatory approach under the assumptions of a flat social marginal benefit curve and uncertainty about the costs and benefits of pollution reduction. However, the paper argues that an adequate carbon tax or a capand- trade system can stimulate firms to turn to green production, depending on their response to the regulatory regime. [ABSTRACT FROM AUTHOR]

An increase in energy demand and consumption is one of the significant challenges of the world community. Global climate change and temperature rise can significantly affect energy demand, especially in the building sector. Green passive design strategies (GPDS) such as green roof and green wall are considered a passive energy-saving technology which can deal with further climate change in near future. This paper compares the energy demand and CO2 emissions of a building with different structural scenarios during the current (2000–2019) and future climatic conditions (the 2050s) in two hot-dry (Kerman) and hot-humid (BandarAbbas) climate samples in Iran. The base case, green roof, and green wall modeling of the selected building have been developed by DesignBuilder software. Results revealed that 61% of the annual energy consumption of Kerman is related to the heating sector, while it will be changed to 47% under the effect of climate change and based on RCP2.6. However, 99% of the annual energy consumption of BandarAbbas belongs to cooling demand and it will not change by 2050s. Also, the maximum heating and cooling energy demand were calculated for the base building. Based on the results, green wall has more efficiency in optimizing total energy consumption compared to green roof in both climate types. On the other hand, GPDS are more efficient to optimize heating energy demand in comparison with cooling energy demand. Furthermore, the green wall strategy has better performance in reducing CO2 emissions as well. Accordingly, CO2 emissions reduce in Kerman by 2.73% and 2.93% by the implementation of the green wall during the observation period and 2050s, respectively. Meanwhile, this strategy can reduce CO2 emissions by only 1% per year in BandarAbbas during all studied periods. [ABSTRACT FROM AUTHOR]

This paper evaluates contributions to global temperature anomalies from greenhouse gas concentrations and from a source of natural variability. There is no accepted causation for the apparent interrelationships between multidecadal oscillations and regime changes in atmospheric circulation, upwelling, and the slowdowns in global surface temperatures associated with a ~60-year oscillation. Exogenous tidal forcing is hypothesized as a major causal agent for these elements, with orthogonal components in tidal forcing generating zonal and meridional regime-dependent processes in the climate system. Climate oscillations are simulated at quasi-biennial to multidecadal timescales by tidal periodicities determined by close approaches of new or full moon to the earth. Subtracting a tidal analog of the ~60-year oscillation from global mean surface temperatures reveals an exponential component comparable with greenhouse gas emission scenarios, and which is responsible for almost 90% or contemporary global temperature increases. Residual subdecadal temperature anomalies correlate with the subdecadal variability of evolved carbon dioxide (CO2), ENSO activity and tidal components, and indicate a causal sequence from tidal forcing to greenhouse gas (GHG) release to temperature increase. Tidal periodicities can all be expressed in terms of four fundamental frequencies. Because of the potential importance of this formulation, tests are urged using general circulation models. [ABSTRACT FROM AUTHOR]

We present an unprecedented set of high‐resolution climate simulations, consisting of a 500‐year pre‐industrial control simulation and a 250‐year historical and future climate simulation from 1850 to 2100. A high‐resolution configuration of the Community Earth System Model version 1.3 (CESM1.3) is used for the simulations with a nominal horizontal resolution of 0.25° for the atmosphere and land models and 0.1° for the ocean and sea‐ice models. At these resolutions, the model permits tropical cyclones and ocean mesoscale eddies, allowing interactions between these synoptic and mesoscale phenomena with large‐scale circulations. An overview of the results from these simulations is provided with a focus on model drift, mean climate, internal modes of variability, representation of the historical and future climates, and extreme events. Comparisons are made to solutions from an identical set of simulations using the standard resolution (nominal 1°) CESM1.3 and to available observations for the historical period to address some key scientific questions concerning the impact and benefit of increasing model horizontal resolution in climate simulations. An emerging prominent feature of the high‐resolution pre‐industrial simulation is the intermittent occurrence of polynyas in the Weddell Sea and its interaction with an Interdecadal Pacific Oscillation. Overall, high‐resolution simulations show significant improvements in representing global mean temperature changes, seasonal cycle of sea‐surface temperature and mixed layer depth, extreme events and in relationships between extreme events and climate modes. Plain Language Summary: Although the current generation of climate models has demonstrated high fidelity in simulating and projecting global temperature change, these models show large uncertainties when it comes to questions concerning how rising global temperatures will impact local weather conditions. This is because the resolution (~100 km) at which the majority of climate models simulate the climate is not fine enough to resolve these small‐scale regional features. Conducting long‐term (multi‐centuries) high‐resolution (~10 km) climate simulations has been a great challenge for the research community due to the extremely high computational demands. Through international collaboration, we are able to address this challenge by delivering an unprecedented set of multi‐century high‐resolution climate simulations using the Community Earth System Model (CESM), capable of directly representing tropical cyclones and extreme rainfall events. In this paper, we give an overall assessment of the value and benefit of the high‐resolution CESM climate simulations by making a direct comparison to an identical set of low‐resolution CESM simulations. We showcase some of the major improvements of the high‐resolution CESM in simulating global mean temperature changes, seasonal cycle of sea‐surface temperature, and extreme events, such as tropical cyclones and relationships between tropical cyclones and El Niño‐Southern Oscillation. Key Points: An unprecedented set of multi‐century high‐resolution Community Earth System Model (CESM) simulations is describedHigh‐resolution CESM simulations reveal a potential role of Southern Ocean polynyas in multidecadal climate variabilityHigh‐resolution CESM exhibits significantly improved simulations of extreme events, such as tropical cyclones and atmospheric rivers [ABSTRACT FROM AUTHOR]

To avoid climate change catastrophe, the world must rapidly transform its economy away from fossil fuels. But to achieve this historically unprecedented task, the news industry must also transform, urged [...]

In a recent, widely covered press release, Larry Fink, chief executive of the world's largest asset management company, BlackRock, pledged significant resources toward developing sustainable investing, for example by offering [...]

This paper examines the performance of three climate re-analysis datasets in Angola, namely the ERA-40, NCEP-r1 and JRA-55, by comparing annual and seasonal estimates of precipitation, surface air temperature and evaporation with ground observation measurements. The observational dataset describes a region poorly covered by international climate databases and it is believed that most of its data have not been used in the data assimilation procedures of the climate models. This paper therefore provides a fresh look at the performance of these climate re-analysis datasets in a vast area where distance and civil war have hindered ground monitoring efforts. The re-analysis exercises offer better temperature estimates than precipitation estimates. When offered, the evaporation estimates from all three products are very poor. The three products are able to describe the main features of the spatial distribution of average annual precipitation and temperature, but struggle to reproduce the temporal changes of these variables. The results from a set of performance criteria show that the correlation between the observed ground measurements and re-analysis estimates is poor overall and the NSE values indicate that the average measured value at each location is usually a better estimate than the re-analysis estimate.EDITOR A. CastellarinASSOCIATE EDITOR S. Kanae [ABSTRACT FROM AUTHOR]

Hydrological sensitivity is the change in global-mean precipitation per degree of global-mean temperature change. This paper shows that the hydrological sensitivity of the response to anthropogenic aerosol forcing is distinct from that of the combined response to all other forcings and that this difference is sufficient to infer the associated cooling in global-mean temperature. This result is demonstrated using temperature and precipitation data generated by climate models and is robust across different climate models. Remarkably, greenhouse gas warming and aerosol cooling can be estimated in a model without using any spatial or temporal gradient information in the response, provided temperature data are augmented by precipitation data. Over the late twentieth century, the hydrological sensitivities of climate models differ significantly from that of observations. Whether this discrepancy can be attributed to observational error, which is substantial as different estimates of global-mean precipitation are not even significantly correlated with each other, or to model error is unclear. The results highlight the urgency to construct accurate estimates of global precipitation from past observations and for reducing model uncertainty in hydrological sensitivity. This paper also clarifies that previous estimates of hydrological sensitivity are limited in that standard regression methods neglect temperature-precipitation relations that occur through internal variability. An alternative method for estimating hydrological sensitivity that overcomes this limitation is presented. [ABSTRACT FROM AUTHOR]

BRIEF INTRODUCTION TO THE PROBLEM: THE GROWING AWARENESS OF CLIMATE CHANGE AND ITS LINK TO CARBON DIOXIDE EMISSIONS HAVE CAUSED CONCERNS IN THE COMMUNITY. A substantial amount of carbon dioxide emitted is due to the energy consumed by residential households. Heating/cooling of a residential house consumes a large proportion of the total household energy. Purpose: This paper explores the concept by comparing thermal efficiency of the four most common external wall structures, with varying amounts of insulation added in the context of Sydney, Australia. Design/methodology/approach: Cost and thermal analysis for each wall type are calculated. Life cycle cost saving and payback period are then evaluated. Findings: It is found that up to 95.7% cost saving can be achieved in heating/cooling in comparing the use of insulated wall systems and air film. Cement sheet wall system is found to be the most cost effective wall system for insulation with minimum 50% of cost saving can be achieved. The results also identify substantial energy cost required for heating/cooling a house without insulation when the climate gets extreme. The payback period for the installation of the insulated wall systems can be achieved in 4.98 years for normal climate condition or 2.58 years for extreme climate condition. Practical implications: The community is currently at great risk of being unable to deal with climate change issue as not clear the effective use of insulated wall systems. This paper can help provide insight and suggestions for residential households in tackling global warming issue. [ABSTRACT FROM AUTHOR]

Data-driven prediction of time series is significant in many scientific research fields such as global climate change and weather forecast. For global monthly mean temperature series, considering the strong potential of deep neural network for extracting data features, this paper proposes a data-driven model, ResGraphNet, which improves the prediction accuracy of time series by an embedded residual module in GraphSAGE layers. The experimental results of a global mean temperature dataset, HadCRUT5, show that compared with 11 traditional prediction technologies, the proposed ResGraphNet obtains the best accuracy. The error indicator predicted by the proposed ResGraphNet is smaller than that of the other 11 prediction models. Furthermore, the performance on seven temperature data sets shows the excellent generalization of the ResGraphNet. Finally, based on our proposed ResGraphNet, the predicted 2022 annual anomaly of global temperature is 0.74722 °C, which provides confidence for limiting warming to 1.5 °C above pre-industrial levels. [ABSTRACT FROM AUTHOR]

Energy production has come under increasing scrutiny as concerns about energy security and climate change have risen. In the UK changes in government structure and privatisation of the electricity industry have led to the emergence of multi-level governance. This means that decisions on how to reduce carbon dioxide emissions from the electricity-generating sector should no longer be solely a national policy decision. Previous studies have sought to explore how renewable energy may develop under multi-level governance, but this paper pays attention to a traditional fossil fuel source, coal, which is still an important means of electricity generation. Coal is the most abundant fossil fuel and advocates argue that carbon capture and storage techniques could make coal ‘clean’, paving the way for a long-term, secure and low emission way to produce energy. This study focuses on the Yorkshire and Humber Region, which has had a long association with coal mining and looks at the implications of this as the region seeks to develop a climate change action plan and an energy strategy within the new regional governance structures. The paper argues that the regional networks developed to address climate change are influenced by existing social power structures and alliances. The region as a territorial structure becomes a useful device in promoting national priorities. [ABSTRACT FROM AUTHOR]

Purpose — In 2007, the issues of global and climate change in particular, have become major issues in the social psyche. With the United Nations declaring 2008 the "International Year of Planet Earth", this; paper aims to look at four recent reports and comments on how the reports aim to deal with the climate and global change challenges ahead. Design/methodology/approach — After a brief introduction to the subject, this paper looks at each of the four reports in turn. It describes the methodology of each report and then discusses its relative strengths and weaknesses. This is followed by a conclusion on the reports as a whole and where policy makers can make improvements. Findings — All four reports are well structured and they have certainly raised the profile and illustrated the importance of global and climate change. However, there are a number of ways each could and should be improved in future updates. Practical implications — This paper aims to bring the reports to a wider audience and make recommendations on improvements to future reports on these important global issues. Originality/value — The paper evaluates four recent reports on the important social issues of global, change and climate change. By comparing and contrasting the reports, the paper gives an overview 01 what some of the larger policy makers are doing to tackle global and climate change. The paper also makes recommendations for improvements to the reports. [ABSTRACT FROM AUTHOR]

The climate is an aggregate of the mean and variability of a range of meteorological variables, notably temperature (T) and precipitation (P). While the impacts of an increase in global mean surface temperature (GMST) are commonly quantified through changes in regional means and extreme value distributions, a concurrent shift in the shapes of the distributions of daily T and P is arguably equally important. Here, we employ a 30‐member ensemble of coupled climate model simulations (CESM1 LENS) to consistently quantify the changes of regionally and seasonally resolved probability density functions of daily T and P as function of GMST. Focusing on aggregate regions covering both populated and rural zones, we identify large regional and seasonal diversity in the probability density functions and quantify where CESM1 projects the most noticeable changes compared to the preindustrial era. As global temperature increases, Europe and the United States are projected to see a rapid reduction in wintertime cold days, and East Asia to experience a strong increase in intense summertime precipitation. Southern Africa may see a shift to a more intrinsically variable climate but with little change in mean properties. The sensitivities of Arctic and African intrinsic variability to GMST are found to be particularly high. Our results highlight the need to further quantify future changes to daily temperature and precipitation distributions as an integral part of preparing for the societal and ecological impacts of climate change and show how large ensemble simulations can be a useful tool for such research. Plain Language Summary: The weather varies naturally from day to day and between regions, seasons, and years. Ecosystems and our society are both adapted to the average weather conditions of a given place and to how variable the temperature and rainfall amounts are around that average. As the global surface temperature changes, whether through natural cycles or human interference, so may this variability. In this paper, we investigate changes to the distributions of daily temperature and rainfall for different levels of surface temperature increase. By using a large set of simulations from the same climate model, we estimate their means and shapes, currently and in the near future. We find that in parts of Europe and the United States, wintertime cold days will disappear more rapidly with global warming than hot days increase, leading to a less variable climate state. In Africa and the Arctic, however, climate conditions will rapidly transition out of the range of preindustrial variability and into a climate state not yet experienced by modern society. We emphasize that in order to prepare for the impacts of climate change, we need information about changes to average properties and to extreme events and about the potential changes to daily variability itself. Key Points: Daily temperature and precipitation distributions from CESM1 Large Ensemble are shown to be functions of region, season, and surface temperatureLarge differences are found in regional distributions, where they are particularly sensitive to surface temperature anomalyWe identify regions where global warming may rapidly shift seasonal climate away from preindustrial conditions [ABSTRACT FROM AUTHOR]

This paper focuses on investigating the role that sustainability entrepreneurship may have in engendering a shift in the practices and operations of contemporary capitalism. Sustainability entrepreneurs are increasingly seen as being in the vanguard of a shift to a new form of capitalist development that can help to address fears over global warming, climate change and their associated negative environmental impacts. Such developments can be set within a wider popular and academic discourse of ecological modernisation, at the heart of which is a relatively optimistic view of the potential for technological change to lead to solutions for environmental problems. This paper focuses on a subset of sustainable entrepreneurs termed 'ecopreneurs' who seek to combine business practice with sustainable development and so transform their business sectors. The paper suggests that work on sustainable entrepreneurship could be substantially improved by an engagement with the literature on transition management in science and technology studies and makes some suggestions as to how such a research agenda could be advanced. [ABSTRACT FROM AUTHOR]

After posing four-broad questions about uncertainty and climate change, Part 1 of this paper provides a review of basic ideas about uncertainty and its treatment in quantitative policy analysis. Part 2 reports very briefly on a series of expert elicitations of climate experts which the author and his colleagues have conducted. The final portion of the paper uses integrated assessment of climate change as a vehicle to explore some limitations to conventional policy analysis and the treatment of uncertainty. Because the climate problem is global in scope, involving many societies, and because it will involve large changes that unfold on a time-scale of several centuries, many standard analytic methods for policy analysis cannot be appropriately applied. Several such difficulties are identified and explored. Strategies for addressing a few of them are discussed. The paper closes by offering answers to the four opening questions. [ABSTRACT FROM AUTHOR]

Increase in global mean temperature and changes in rainfall amount, pattern, and distribution over the world are all indicative of climate change events. These changes alter the hydroclimatic condition of regions as well as the availability of water resources. In this study, the data generated by 14 general circulation models (GCMs) developed under the Special Report on Emissions Scenarios (SRES) A1B, A2, and B2 are downscaled and utilized to evaluate climate change impact on the hydroclimatic system of the Karaj River basin located in central Iran. The precipitation and temperature of the study region are downscaled using the change factor approach (CFA). The study analyzes future climate data, extreme changes of future climatic conditions of precipitation, and temperature. The Hydrologiska Byråns Vattenbalansavdelning (HBV) model developed by the Swedish Meteorological and Hydrological Institute (SMHI) is used to simulate streamflow under extreme climate change conditions. Two different sources of uncertainty are investigated in this study. First, the model parameters uncertainty is analyzed with the Monte Carlo procedure, and then different datasets of GCMs projection are investigated under the climate of the twentieth-century climate simulation (20C3M). Results show the GCMs projections range can almost capture the historical records during the 1980s through 2000 for the Karaj basin. By applying the HBV model, considerable range of streamflow changes in the future can be projected that will affect the operation scheme of Karaj Reservoir. In this study, the system dynamics (SD) modeling approach is used to simulate the system behavior through time in an integrated fashion and evaluate its overall reliability in supplying water. The results of this study show that the runoff will decrease in the future under the climate change impact. This will result in more than 50% decrease in reliability of the Karaj Reservoir system under the extreme conditions. As a result, this research predicts that the Karaj Reservoir system will face more than 50% decrease in its reliability under the extreme conditions. Consequently, meeting the increasing water demands would be difficult and application of demand management strategies will be unavoidable. [ABSTRACT FROM AUTHOR]

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Kretzschmar et al., in a comment in 2017, use the spread in the output of aerosol-climate models to argue that the models refute the hypothesis (presented in a paper by Stevens in 2015) that for the mid-twentieth-century warming to be consistent with observations, then the present-day aerosol forcing, must be less negative than −1 W m−2. The main point of contention is the nature of the relationship between global SO2 emissions and In contrast to the concave (log-linear) relationship used by Stevens and in earlier studies, whereby becomes progressively less sensitive to SO2 emissions, some models suggest a convex relationship, which would imply a less negative lower bound. The model that best exemplifies this difference, and that is most clearly in conflict with the hypothesis of Stevens, does so because of an implausible aerosol response to the initial rise in anthropogenic aerosol precursor emissions in East and South Asia-already in 1975 this model's clear-sky reflectance from anthropogenic aerosol over the North Pacific exceeds present-day estimates of the clear-sky reflectance by the total aerosol. The authors perform experiments using a new (observationally constrained) climatology of anthropogenic aerosols to further show that the effects of changing patterns of aerosol and aerosol precursor emissions during the late twentieth century have, for the same global emissions, relatively little effect on These findings suggest that the behavior Kretzschmar et al. identify as being in conflict with the lower bound in Stevens arises from an implausible relationship between SO2 emissions and and thus provides little basis for revising this lower bound. [ABSTRACT FROM AUTHOR]