The need for and use of socio-economic scenarios for climate change analysis: A new approach based on shared socio-economic pathways

The diversity of socio-economic pathways and CO2 emissions scenarios: Insights from the investigation of a scenarios database

The climate of the Earth is changing in response to natural and anthropogenic forcing agents. Emissions of greenhouse gases and air pollutants have led to significant changes in the Earth’s climate systems and projections indicate that further extensive changes are likely. Increased scientific understanding into the processes responsible for climate change and the possible consequences of assumptions regarding future climate and air pollution policy is important to formulate effective response strategies based on mitigation and adaptation. Earth System Models (ESMs) can be used to make climate projections based on emissions or concentrations projections for greenhouse gasses and aerosols derived from socio-economic scenarios. Such scenarios are produced by Integrated Assessment Models (IAMs), based on detailed descriptions of population growth, energy demand and land use. There has been increasing interest in coupling different disciplines involved in climate research. The current cooperation efforts among scientists from different disciplines have led to an improved representation of climate forcings in ESMs, and of climate responses impacts in IAMs. In this thesis, we contribute to this cooperation by exploring the consequences of emission scenarios under different assumptions regarding air pollution and climate policy. To do so, we utilize a set of scenarios similar to the Representative Concentration Pathways (RCPs), developed using the IAM IMAGE. These scenarios combine scenarios with radiative forcing targets in 2100 of 2.6 W/m2 and 6.0 W/m2 with different assumptions for air pollution policies (low/high). These scenarios are subsequently used in the global atmospheric chemistry and transport model TM5. Results reveal that both climate and air pollution control policies have large-scale impacts on pollutant concentrations, often of comparable magnitude. We also find that air pollution control measures could, on a global scale, significantly reduce the warming induced by tropospheric ozone and black carbon and the cooling resulting from sulphate in the coming decades. These effects tend to cancel each other on a global scale. Next, we evaluate the equilibrium climate response to aerosol reductions in different parts of the world in 2050, using the global climate model EC-Earth. Reductions in aerosol concentrations increase downward surface solar radiation and surface temperature concomitantly in various parts of the world. The increase in surface temperature is dominated by the reduced cooling effect of sulphate which in some areas is partially compensated by the decreased warming effect of black carbon. Also, we find that aerosol reductions can significantly affect climate at high latitudes especially in the winter, mostly as a result of teleconnections between the low and high latitudes. Due to the inhomogeneous spatial distributions of air pollutants, changes in their emissions can have strong regional climate impacts. Using EC-Earth, we assess in Chapter 4 the effectiveness of different aerosol forcing agents in causing climate change in 2050. Our results show that different anthropogenic aerosol components may have a broad range ofefficacies. The results also reveal that there are large interhemispheric differences in aerosol forcings, which result in changes in circulation patterns. By using surface ozone concentrations simulated by TM5 as input to IMAGE, we estimate ozone impacts on crop production, and subsequent impacts on land use and carbon fluxes in 2005 and 2050. In the absence of new climate and air pollution policies, higher ozone concentrations could lead to an increase in crop damage in 2050 compared to present day. This may lead to a global increase in crop area notably in Asia. Implementation of air pollution policies and climate policies (co-benefits of reducing ozone precursor emissions) could limit future crop yield losses due to ozone in the most affected regions. At the local scale, the changes can be substantial.

Abstract. Climate policy analysis needs reference scenarios to assess emission targets and current trends. When presenting their national climate policies, countries often showcase their target trajectories against fictitious so-called baselines. These counterfactual scenarios are meant to present future greenhouse gas (GHG) emissions in the absence of climate policy. These so-called baselines presented by countries are often of limited use, as they can be exaggerated and as the methodology used to derive them is usually not transparent. Scenarios created by independent modeling groups using integrated assessment models (IAMs) can provide different interpretations of several socio-economic storylines and can provide a more realistic backdrop against which the projected target emission trajectory can be assessed. However, the IAMs are limited in regional resolution. This resolution is further reduced in intercomparison studies, as data for a common set of regions are produced by aggregating the underlying smaller regions. Thus, the data are not readily available for country-specific policy analysis. This gap is closed by downscaling regional IAM scenarios to the country level. The last of such efforts has been performed for the SRES (“Special Report on Emissions Scenarios”) scenarios, which are over a decade old by now. CMIP6 (Coupled Model Intercomparison Project phase 6) scenarios have been downscaled to a grid; however they cover only a few combinations of forcing levels and SSP storylines with only a single model per combination. Here, we provide up-to-date country scenarios, downscaled from the full RCP (Representative Concentration Pathway) and SSP (Shared Socio-Economic Pathway) scenario databases, using results from the SSP GDP (gross domestic product) country model results as drivers for the downscaling process. The data are available at https://doi.org/10.5281/zenodo.3638137 (Gütschow et al., 2020).

Investigating the role of surface engineering in mitigating greenhouse gas emissions of energy technologies: An outlook towards 2100

The role of nuclear in China's energy future: Insights from integrated assessment

Characterizing the role of socioeconomic pathways in shaping future urban heat-related challenges

Deforestation has contributed significantly to net greenhouse gas emissions, but slowing deforestation, regrowing forests and other ecosystem processes have made forests a net sink. Deforestation will still influence future carbon fluxes, but the role of forest growth through aging, management, and other silvicultural inputs on future carbon fluxes are critically important but not always recognized by bookkeeping and integrated assessment models. When projecting the future, it is vital to capture how management processes affect carbon storage in ecosystems and wood products.This study uses multiple global forest sector models to project forest carbon impacts across 81 shared socioeconomic (SSP) and climate mitigation pathway scenarios. We illustrate the importance of modeling management decisions in existing forests in response to changing demands for land resources, wood products and carbon. Although the models vary in key attributes, there is general agreement across a majority of scenarios that the global forest sector could remain a carbon sink in the future, sequestering 1.2–5.8 GtCO2e/yr over the next century. Carbon fluxes in the baseline scenarios that exclude climate mitigation policy ranged from −0.8 to 4.9 GtCO2e/yr, highlighting the strong influence of SSPs on forest sector model estimates. Improved forest management can jointly increase carbon stocks and harvests without expanding forest area, suggesting that carbon fluxes from managed forests systems deserve more careful consideration by the climate policy community.

The work of Intergovernmental Panel on Climate Change (IPCC) on a Special Report on Emission Scenarios has pioneered the methods for greenhouse gas emission scenario associated with socio-economic development pathways in the coming century, followed by other models such as the Shared Socio-economic Pathways (SSPs) in climate change and disaster risk. This scenario is useful to understand how human society develops the future assessment of climate change and to provide possible mitigation and response strategies. This chapter is aimed to review the current status of socio-economic scenario on climate change and disaster and risk reduction effort in scholarly literatures and to identify gaps and opportunities for future research and decision-making based on the reflection of existing Climate Change Adaptation (CCA) and Disaster Risk Reduction (DRR) theories and emblematic case studies. We have conducted a semi-structured literature review and content analysis. The result of our analysis revealed that there is still a dearth of study on the application of different models of socio-economic forecasting scenarios to understand how would each pathway affect the vulnerability of certain type of disaster and its potential as a decision-making tool in Indonesia. However, there are opportunities to expand the methods and define socio-economic variables that go beyond the economic indicators (i.e. GDP), such as of welfare, health, education, social capital human development, participation and technology. Challenges are also identified, including the limitation of methodology, availability of data, lack of synergy between CCA and DRR, lack of interdisciplinarity, space for science–policy interface and political support. Future research on SSPs should pay attention to the aspect of multi-hazard approaches to climate change impact, emerging technology and its adverse impacts. We argued that projection is a highly important tool; however, largely reliable at the global scale rather than regional or national scale. To understand that climate variability and change is high, it is important to raise self-awareness on adaptation to future disasters.

PurposeThe use of socio-economic scenarios in small island developing states (SIDS) when assessing, and planning for, the impacts of global changes on national socioeconomic and environmental systems is still in its infancy. The research conducts a cross-scale foresight scenario exercise to produce regional scenarios and national storylines for Caribbean islands that are of “partial” consistency to the shared socioeconomic pathways (SSPs) and representative concentration pathways (RCPs) and shows how future socioeconomic and climatic changes can be applied to inform natural resource management decisions.Design/methodology/approachTo develop the scenarios, the study uses a three-staged linking process using mixed methods to “triangulate” each technique to compensate for weaknesses of one method by introducing a complementary method at each stage. A participatory-expert stepwise approach with feedback loops is used and complemented with a climate sensitive tourism water demand model.FindingsFour regional exploratory socio-economic scenarios were constructed that are partially consistent with global scenarios. In addition, national storylines for four island states were developed based on the regional scenarios. Using RCP 4.5 hotel water demand in Barbados is estimated under three of the regional scenarios based on compatibility. The results indicate there is a 17% difference between the highest and lowest estimated water demand, indicating the effect of varying socio-economic conditions on water demand.Originality/valueThe paper contributes to the literature by presenting regional socio-economic scenarios, specifically for SIDS, that are partially consistent with both global climatic RCPs and SSPs using a cross-scale approach. The scenarios are then used to demonstrate how future socio-economic pathways impact on freshwater demand.

Climate action is goal 13 of UN’s 17 Sustainable Development Goals (SDG). Future impacts of climate change depend on climatic changes, the level of climate change policy, both mitigation and adaptation, and socio-economic status and development pathways. To investigate the climate change policy impact of socio-economic development pathways, we develop three pathways. Climate change affects socio-economic development in many ways. We interpret global storylines into South Korean contexts: Shared Socio-economic Pathway 1 (SSP1), SSP2, and SSP3 for population, economy, and land use. SSP elements and proxies were identified and elaborated through stakeholder participatory workshops, demand survey on potential users, past trends, and recent national projections of major proxies. Twenty-nine proxies were quantified using sector-specific models and downscaled where possible. Socio-economic and climate scenarios matrixes enable one to quantify the contribution of climate, population, economic development, and land-use change in future climate change impacts. Economic damage between climate scenarios is different in SSPs, and it highlights that SSPs are one of the key components for future climate change impacts. Achieving SDGs generates additional incentives for local and national governments as it can reduce mitigation and adaptation policy burden.

Land use and land cover scenarios: An interdisciplinary approach integrating local conditions and the global shared socioeconomic pathways

Land use change and water supply–demand assessment are critical to achieving regional sustainable development and improving human wellbeing. In the context of complex climate change and socioeconomic development, there is an urgent need for systematic assessment and forecasting studies on how to combine physical, geographical, and socioeconomic factors to clarify patterns of change in the land use change and water supply–demand, as well as to respond appropriately to different climate and socioeconomic development scenarios in the future. Based on the Shared Socioeconomic Pathways-Representative Concentration Pathway (SSP-RCP) scenarios, a framework for simulating future land use change and assessing water supply–demand in the coupled SD-PLUS-InVEST model was constructed. The land use change in Guizhou Province from 2020 to 2050 was simulated using the SD-PLUS model, and the water supply–demand conditions were projected for 2030, 2040, and 2050 under multiple scenarios (SSP126, SSP245, and SSP585). The research results indicated that (1) The land use change in the study area has significant spatial heterogeneity. It showed similar trends in the land use change in the SSP126 and SSP245 scenarios, with both artificial surfaces and forest showing an expansion trend, but the expansion of forest was most typical in the southwestern region in the SSP126 scenario, and there is a significant increase in the northeastern region in the SSP245 scenario. Additionally, there is a rapid expansion of artificial surfaces in the central region in the SSP585 scenario, and a more rapid expansion of cultivated land in the southeastern region, with a significant increase in the area of water bodies. (2) The changes in water supply from 2020 to 2050 under the three scenarios show a smaller increase (5.22–11.88%), a significant increase in water demand (29.45–58.84%), and an increase in the area of water shortage by about 2708.94–9084.40 km2, with the extent of the shortage increasing by about 23.71–79.50%. (3) According to the results of the SSP-RCP scenario projections, socioeconomic development has a significant impact on the growth of water demand, and climate and land use change may exacerbate the spatiotemporal heterogeneity of water supply–demand in the karst region. The systematic study of land use change and water supply–demand in Guizhou can provide a scientific basis for the sustainable management of regional ecosystems and the rational allocation of land and water resources.

Integrated assessment models (IAMs) have commonly been used to understand the relationship between the economy, the earth’s climate system and climate impacts. We compare the IPCC simulations of CO2 concentration, radiative forcing, and global mean temperature changes associated with five SRES ‘marker’ emissions scenarios with the responses of three IAMs—DICE, FUND and PAGE—to these same emission scenarios. We also compare differences in simulated temperature increase resulting from moving from a high to a low emissions scenario. These IAMs offer a range of climate outcomes, some of which are inconsistent with those of IPCC, due to differing treatments of the carbon cycle and of the temperature response to radiative forcing. In particular, in FUND temperatures up until 2100 are relatively similar for the four emissions scenarios, and temperature reductions upon switching to lower emissions scenarios are small. PAGE incorporates strong carbon cycle feedbacks, leading to higher CO2 concentrations in the twenty-second century than other models. Such IAMs are frequently applied to determine ‘optimal’ climate policy in a cost–benefit approach. Models such as FUND which show smaller temperature responses to reducing emissions than IPCC simulations on comparable timescales will underestimate the benefits of emission reductions and hence the calculated ‘optimal’ level of investment in mitigation.

In this study, the focus is on investigating how different climate scenarios, as they have been adopted in Phase 6 of the Coupled Model Intercomparison Project (CMIP6), can lead to different regimes in the energetics components in Lorenz’s energy cycle, hence impacting the “working rate” of the climate system, which is considered as a “heat engine.” The four energy forms on which this investigation is based on are the zonal and eddy components of the available potential and kinetic energies. The permissible correspondingly considered transformations between these forms of energy are also studied. Generation of available potential energy and dissipation of kinetic energy complete the Lorenz energy cycle that is adopted here. In the CMIP6 approach, the results of different climate change analyses were collected in a matrix defined by two dimensions: climate exposure as characterized by a radiative forcing or temperature level and socioeconomic development as classified by the pathways, known as Shared Socioeconomic Pathways (SSPs). The basis of the calculations in this study is the climatic projection produced by the HadGEM3-GC3.1-LL climatic model in the period from 2015 to 2100. In this respect, the results are presented in terms of time projections of the energetics components under different SSPs. The results have shown that the different SSPs yield diverse energetics regimes, consequently impacting on Lorenz energy cycle and, hence, a “working rate” of the climate system based on the components of this cycle. In this respect, Lorenz energy cycle projections are presented, under different SSPs. The results are also contrasted to the calculations for the historical period 1929 to 2014 as this is simulated by the same climatic model.

Drylands are often overlooked in broad conservation frameworks and development priorities and face increasing threats from human activities. Here we evaluated the formal degree of protection of global drylands, their land vertebrate biodiversity and current threats, and projected human-induced land-use changes to drylands under different future climate change and socioeconomic scenarios. Overall, drylands have lower protected-area coverage (12%) compared to non-drylands (21%). Consequently, most dryland vertebrates including many endemic and narrow-ranging species are inadequately protected (0-2% range coverage). Dryland vertebrates are threatened by varied anthropogenic factors-including agricultural and infrastructure development (that is, artificial structures, surfaces, roads and industrial sites). Alarmingly, by 2100 drylands are projected to experience some degree of land conversion in 95-100% of their current natural habitat due to urban, agricultural and alternative energy expansion. This loss of undisturbed dryland regions is expected across different socioeconomic pathways, even under optimistic scenarios characterized by progressive climate policies and moderate socioeconomic trends.