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The occurrence frequency of forest fires (OF) can be estimated using drought features because droughts are affected by climatic conditions. Previous studies have improved OF estimation performance by applying the meteorological drought index to climatic conditions. It is anticipated that the temperature will rise in South Korea in the future and that drought will become severe on account of climate change. The future OF is expected to change accordingly. This study used the standard precipitation index, relative humidity, and wind speed as predictor variables for a deep-learning-based model to estimate the OF. Climate change scenarios under shared socioeconomic pathways were used to estimate future OF. As a result, it was projected that the OF in the summer season will increase in the future (2071–2100). In particular, there will be a 15% increase in July compared to the current climate. A decrease in relative humidity and increase in wind speed will also affect the OF. Finally, drought severity was found to be the most influential factor on the OF among the four drought characteristics (severity, duration, intensity, and inter-arrival), considering inter-model variability across all global climate models.

Floods are among the most devastating climate-induced hazards, with severe socio economic consequences, particularly in underdeveloped countries. Pakistan is highly vulnerable to climate change and has experienced several catastrophic flood events in recent decades. This study assesses future flood risks in the Panjkora River Basin, one of the major catchments in Khyber Pakhtunkhwa province, using hydrological and hydraulic modeling under different climate change scenarios. The Soil and Water Assessment Tool (SWAT) was employed to simulate hydrological processes using a 29-year weather dataset (1981-2010). Model calibration (1981-2002) and validation (2003-2010) demonstrated strong performance, with coefficient of determination (R²) values of 0.731 and 0.721 and Nash-Sutcliffe efficiency (NSE) values of 0.72 and 0.71, respectively. Future projections were analyzed under Shared Socioeconomic Pathways (SSP 2-4.5, moderate emissions, and SSP 5-8.5, high emissions) for three periods: near future (2026-2 mid-century (2051-2075), and late century (2076 2099). Flood inundation mapping was conducted using the Hydrologic Engineering Centre's River Analysis System (HEC-RAS). The results reveal a significant increase in flood inundation, particularly under SSP 5-8.5. Discharge is projected to increase by approximately 25% under SSP 2-4.5 and 27% under SSP 5-8.5 compared to the historical baseline. These findings underscore the increasing flood risks in the Panjkora River Basin under future climate change scenarios and highlight the need for adaptive water resource management and disaster risk reduction strategies in the region.

The future availability of mineral resources has attracted much attention; therefore, a quantitative evaluation of the potential impacts of resource use on future availability is important. Although the surplus cost model is often recommended among the existing endpoint characterization models of mineral resources, it has a shortcoming as it does not consider the changes in future primary resource use. This paper introduces a new characterization model considering future primary resource use changes, due to future changes in total demand and secondary resource use. Using material flow analysis, this study estimated time-series primary resource use for iron and copper for five shared socioeconomic pathways (SSPs) and a constant total demand scenario. New characterization factors, i.e., demand change-based surplus costs (DCSC), are calculated for each resource. In all of the SSPs, the calculated DCSCs are larger than the conventional surplus costs (SC) for both iron and copper. The DCSC, relative to the SC of copper, is larger than that of iron for all of the SSPs, which suggests that the potential impacts of copper use, relative to iron, will be underestimated, unless future primary resource use changes are considered. In calculating DCSC for other resources, it is important to choose an appropriate approach for forecasting future total demands.

Climate change is expected to result in more frequent and intense heat waves (HWs) in South Asia (SA). The simultaneous increases in temperature and population will exacerbate the population exposure to future HWs. Here we estimate the future population exposure to daytime and nighttime HWs in SA using the Coupled Model Intercomparison Project 6 (CMIP6) models under four Shared Socioeconomic Pathways (SSPs) during 2061–2100, relative to 1975–2014. The results show that the projected frequency and spatial extent of the daytime (nighttime) HWs will be higher under scenario SSP5‐8.5, followed by SSP2‐4.5, SSP3‐7.0, and SSP1‐2.6 (SSP5‐8.5, followed by SSP3‐7.0, SSP2‐4.5, and SSP1‐2.6), relative to the historical period. The approach presented here allows decomposing the effects of climate change and future population on the overall exposure. The results reveal that the compounding effects of projected trends in population and HWs will significantly escalate the population exposure to HWs. Under the selected SSPs, the total population exposure to daytime and nighttime HWs ranges from 185 to 492 and 204–555 million people‐event, respectively, with the maximum exposure occurring in the Indo‐Gigantic Plain. The wide range of exposed populations highlights the sensitivity of the overall exposure to our future socioeconomic pathway decisions, emphasizing the importance of curbing anthropogenic greenhouse gas emissions and adopting sustainable urban planning solutions to minimize the potential socioeconomic and health impacts of HWs. Plain Language Summary Climate change will intensify the occurrence and intensity of heatwaves (HWs) in South Asia, with severe impacts on the population. Here we estimate the population exposure to daytime and nighttime HWs using the Coupled Model Intercomparison Project 6 (CMIP6) models under four Shared Socioeconomic Pathways (SSPs). The results show that the projected daytime and nighttime HWs will impact around 185–492 and 204–555 million people under the selected SSPs, respectively, with the maximum exposure occurring in the Indo‐Gigantic Plain. The wide range of populations under different SSPs highlights the sensitivity of the population to future SSP decisions. This emphasizes the importance of reducing greenhouse gas emissions and adopting sustainable urban planning solutions to minimize the potential socioeconomic and health impacts of HWs. Key Points The number and extent of heat waves (HWs) are projected to increase under all the Shared Socioeconomic Pathways (SSPs) The population exposure to HWs ranges from 185 to 555 million people‐event with the highest exposure in the Indo‐Gigantic Plain Compounding effects of climate change and population increase substantially aggravate exposure to HWs

Carbon stored in harvested wood products (HWPs) can affect national greenhouse gas (GHG) inventories, in which the production and end use of HWPs play a key role. The Intergovernmental Panel on Climate Change (IPCC) provides guidance on HWP carbon accounting, which is sensitive to future developments of socioeconomic factors including population, income, and trade. We estimated the carbon stored within HWPs from 1961 to 2065 for 180 countries following IPCC carbon-accounting guidelines, consistent with Food and Agriculture Organization of the United Nations (FAOSTAT) historical data and plausible futures outlined by the shared socioeconomic pathways. We found that the global HWP pool was a net annual sink of 335 Mt of CO₂ equivalent (CO₂e)·y−1 in 2015, offsetting substantial amounts of industrial processes within some countries, and as much as 441 Mt of CO₂e·y−1 by 2030 under certain socioeconomic developments. Furthermore, there is a considerable sequestration gap (71 Mt of CO₂e·y−1 of unaccounted carbon storage in 2015 and 120 Mt of CO₂e·y−1 by 2065) under current IPCC Good Practice Guidance, as traded feedstock is ineligible for national GHG inventories. However, even under favorable socioeconomic conditions, and when accounting for the sequestration gap, carbon stored annually in HWPs is <1% of global emissions. Furthermore, economic shocks can turn the HWP pool into a carbon source either long-term—e.g., the collapse of the USSR—or short-term—e.g., the US economic recession of 2008/09. In conclusion, carbon stored within end-use HWPs varies widely across countries and depends on evolving market forces.

Extreme weather events severely impact human and natural systems, and their impacts would be exacerbated when events occur synchronously. Extensive studies have examined changes in individual events under global warming, but changes in the synchrony of multiple events remain less understood. Here we quantify the synchrony of extreme heat and precipitation events over global land areas and assess how it responds to climate change. We show regional disparities with stronger synchrony in lower latitudes and weaker in middle latitudes. Since the 1980s, the synchrony has increased by 34%, especially in the tropics and northern high latitudes. Climate simulations project an 87% increase by 2100 under Shared Socioeconomic Pathway (SSP) 5–8.5 relative to historical level, while low‐emission scenarios (SSP1‐2.6 and SSP2‐4.5) can help mitigate the increased risk of synchronous events. Increasing synchrony is primarily driven by climate warming, and this scaling relationship depends on global warming level rather warming path. Plain Language Summary The synchrony describes the temporal coordination and the degree to which two different events occur synchronously or in close successions. Here we provide a global assessment of the changes in the synchrony of extreme heat and precipitation events, which are typically considered as separate occurrences. We find that human‐induced climate warming causes worldwide increases in the synchrony of extreme heat and precipitation events, with their magnitude depending on the level of warming, rather than the specific warming path. Our study highlights the urgent need to mitigate the increasing threats posed by synchronous heat and precipitation events. Key Points Synchrony of extreme heat and precipitation events has increased worldwide since 1979, especially in tropics and northern high latitudes Synchrony will further increase by 87% by the end of the 21st century relative to 1940–2014 under high‐emission scenario (SSP5‐8.5) Synchrony increases are primarily driven by climate warming, and the increase magnitude depends on warming level, rather warming path

This paper describes the scenario matrix architecture that underlies a framework for developing new scenarios for climate change research. The matrix architecture facilitates addressing key questions related to current climate research and policy-making: identifying the effectiveness of different adaptation and mitigation strategies (in terms of their costs, risks and other consequences) and the possible trade-offs and synergies. The two main axes of the matrix are: 1) the level of radiative forcing of the climate system (as characterised by the representative concentration pathways) and 2) a set of alternative plausible trajectories of future global development (described as shared socio-economic pathways). The matrix can be used to guide scenario development at different scales. It can also be used as a heuristic tool for classifying new and existing scenarios for assessment. Key elements of the architecture, in particular the shared socio-economic pathways and shared policy assumptions (devices for incorporating explicit mitigation and adaptation policies), are elaborated in other papers in this special issue.

Until 2012, most of China’s population lived in rural areas with markedly different patterns of household energy consumption from those in Chinese cities. The studies so far done on residential energy use in rural Chinese households have been limited to questionnaire surveys and panel data analyses. Hardly any studies on energy demand in rural areas have considered both the climatic and economic disparities across Chinese regions. In this study we conduct a systematic analysis of the rural Chinese residential sector on a regional basis. We begin by developing a macro-model to estimate energy service demands up to 2050. Next, we apply the AIM(Asia-Pasific Integrated Model)/Enduse model, a bottom-up cost-minimization model with a detailed mitigation technology database, to estimate the mitigation potential of low-carbon technologies in rural China. Our results show that energy service demand in the rural household sector will continue to increase in regions with growing population or income conditions. However, after 2030, the rural residential energy service demand will start to decline in most Chinese regions. The impacts of efficient technologies will vary from one region to the next due to regional climatic and economic disparities. Throughout all of China, the penetration of efficient technologies can reduce CO2 emissions by 20% to 50%. Of the technologies available, efficient lighting, biomass water heaters, and efficient electronics bring the most benefit when implemented in rural households.

Coastal areas are subject to hazards that can result in severe impacts due to the high concentration of people and assets in exposed locations. While climate-induced sea-level rise will exacerbate these hazards in the course of the 21st century, future dynamics in socioeconomic development will play an important role in driving impacts – as well as adaptation responses – in particular in countries with rapid population growth in low-lying coastal areas. Here, we synthesize the current state of knowledge related to current and future population development in coastal locations and the underlying trends in socioeconomic development affecting coastal impacts at continental to global scales. Currently, 2.15 billion people live in the near-coastal zone and 898 million in the low-elevation coastal zone globally. These numbers could increase to 2.9 billion and 1.2 billion, respectively, depending on the socioeconomic scenario (i.e., Shared Socioeconomic Pathway [SSP]) considered. Nevertheless, although these numbers indicate a rapid increase in exposure of population and assets to coastal hazards, they bear limited information about the actual impacts as they do not include information on the vulnerability of coastal population. Based on these insights, we stress the need to account for dynamics in socioeconomic development in coastal risk assessments, including exposure as well as vulnerability, and additionally exploring potential feedbacks due to adaptation responses and migration decisions. Last, we propose action points for future work that can inform long-term coastal planning for managing coastal risks.

The scientific community is developing new global, regional, and sectoral scenarios to facilitate interdisciplinary research and assessment to explore the range of possible future climates and related physical changes that could pose risks to human and natural systems; how these changes could interact with social, economic, and environmental development pathways; the degree to which mitigation and adaptation policies can avoid and reduce risks; the costs and benefits of various policy mixes; and the relationship of future climate change adaptation and mitigation policy responses with sustainable development. This paper provides the background to and process of developing the conceptual framework for these scenarios, as described in the three subsequent papers in this Special Issue (Van Vuuren et al., 2013; O’Neill et al., 2013; Kriegler et al., Submitted for publication in this special issue). The paper also discusses research needs to further develop, apply, and revise this framework in an iterative and open-ended process. A key goal of the framework design and its future development is to facilitate the collaboration of climate change researchers from a broad range of perspectives and disciplines to develop policy- and decision-relevant scenarios and explore the challenges and opportunities human and natural systems could face with additional climate change.