Impacts World 2017

In the run-up to the Paris negotiations and thereafter, there has been heated debate as to what the Loss and Damage debate should cover. Some analysts and observers suggest it should provide tested risk management measures including technologies to those that are in dire need for support due to increasing climate-related risk, while others suggest compensation is to be considered. Other voices consider the debate to largely be of symbolic character emphasising the need to avoid dangerous climate change by heavy mitigation. Many insiders have been wondering whether these perspectives can be disentangled and even reconciled. We suggest that there is potential for doing so and assert that the space for the Loss and Damage mechanism overall can be defined to encompass "transformative measures for avoiding and managing intolerable risks as well as curative measures for dealing with unavoided and unavoidable impacts." The suggestions build on three lines of analysis, which have been fundamental for the debate on Loss and Damage. The first is a broad view towards jointly considering climate change and climate variability, thus providing a link to expertise around disaster risk management for managing today's adaptation deficits. The other building block is a consideration for risk preference, which in this context is framed as risk acceptance, tolerance, and intolerance in order to consider any limits to adaptation. Finally, we suggest a balance between distributive and compensatory justice as essential. This implies taking a distributive justice perspective, referring to sharing burdens in a demand-driven mode among agents without a need for causal climate attribution (the set-up in the DRM space currently), while compensatory justice, referring to the unequal levels of historical and current emissions produced, is to be upheld as well as a key principle motivating additional support and funding for managing climate-related risk. Overall, our discussion provides a principled framework for aligning perspectives and discussing policy options, incl. financing, climate-related insurance, comprehensive disaster risk management and a climate displacement facility, which are all options that are under discussion as the climate negotiations are going forward. The talk presents the rationale and some first quantification of the cost of supporting the implementation of the options discussed.

Global water withdrawals for beneficial purposes have been increasing substantially in the last century, driven by the growth in population and income. The ensuing damages have been building up rapidly during recent years, with many basins around the world undergoing pervasive water scarcity conditions. Moreover, impacts of future climatic and socio-economic changes are projected to further exacerbate supply deficit in those basins. Therefore, the design of adaptation strategies to address future water challenges is needed. This task requires quantitative tools for planning and policy evaluation that integrate various metrics, reflecting decision-making objectives and processes. This study presents a global hydro-economic modeling framework newly developed at IIASA that represents water resource systems, management options and associated economic values in an integrated manner. The model incorporates an optimization procedure aimed at balancing demand and supply of water at the level of large-scale river basins worldwide. The model uses information on water demand and availability provided by existing global integrated assessment models and global hydrological models. In this study, the model is used to evaluate the effects of reduced water availability under future climate change scenarios. The model is applied to basins in Africa which provides a challenging case study. However, the modeling framework is designed to be adaptable for any basin elsewhere. Model results show the economic and environmental tradeoffs among the different adaptation policy choices and the hurdles facing these policies. Specifically, our results suggest that addressing the challenge of adaptation to growing water scarcity in Africa will require major investments in more efficient water use technologies and unconventional freshwater supply options, such as wastewater recycling and desalination, with potential consequences on water supply costs, energy use and carbon emissions.

Previous climate change impact assessments of the domestic agricultural sector have relied in part on domestic partial equilibrium models of the agriculture and other land use sectors. While such models often provide substantial detail on domestic production systems needed for climate impact assessments, these tools typically hold agricultural supply functions fixed in the rest of the world. Thus, even with endogenous trade flows, domestic partial equilibrium models ignore potential systemic productivity changes globally under assumed climate change scenarios. Country-scale assessments that do not explicitly account for global market interactions or adjust future productivity assumptions in the rest of the world to account for climate change can result in biased projections of domestic climate change impacts. These studies also explicitly focus on the adaptation issue rather from the producers than consumers perspective. To evaluate the potential limitation of country-scale climate impact assessments, this study applies a global model of agriculture and forestry to evaluate climate change impacts on U.S. agriculture with and without accounting for climate change impacts in the rest of the world. To this team’s knowledge, this is the first attempt to quantify the relative difference in U.S. agricultural sector climate change impacts with and without directly accounting for climate change in the rest of the world. This is accomplished through a unique scenario design that first isolates several climate change scenarios and exogenous crop yield impacts to the U.S. only, followed by scenarios that extend the climate impacts to the rest of the world. Then, additional sensitivity analysis is conducted in which global agricultural trade is more rapidly liberalized, which provides a buffer against domestic productivity shocks brought on by climate change. This manuscript focuses on U.S. results to illustrate the potential importance of accounting for global climate impacts when projecting domestic impacts.

The Shared Socioeconomic Pathways (SSPs) provide a framework and projections for assessing scenarios of socioeconomic change alongside climate impacts and options for mitigation and adaptation. The development of spatial socioeconomic datasets now facilitates impacts and vulnerability assessment from climate impact models. We calculate a set of climate impact indicators covering water, energy and land sectors (e.g. changes in runoff, discharge and water scarcity, cropland change and biodiversity, energy demand change and heatwave frequency) from an ensemble of global and climate and hydrological impact models (ISIMIP). These are combined with novel spatial socioeconomic datasets of population, urbanization, income distribution and wealth projections, to investigate multiple climate impacts on the world’s poorest populations. Using policy relevant scenarios of 1.5°C, 2.0°C and 3.0°C and the 5 SSPs, we identify hotspots of vulnerable populations to climate impacts. This combination of scenarios enables us to decompose the differences between the socioeconomic and climate projections to understand the dominant drivers of vulnerability to multiple climate impacts. Threshold approaches and use of spatial data allows for novel presentation of critical hotspots and how the severity and spatial extents change with time. We then aggregate these results at relevant decision-making scales, such as country- and river basin-level, whilst the multi-model approach enables measures of model uncertainty to be incorporated into the analysis. In the near term, we find that for the majority of locations the difference between 1.5°C and 2.0°C is small and equivalent to (and sometimes outweighed) by uncertainty between different socioeconomic projections. Climate impacts at 3°C are spatially extensive and more severe, impacting larger populations and subsequently more sensitive to socioeconomic projections. The combination of these approaches to identify multi-impact vulnerabilities and multi-sector vulnerabilities not only allows crucial identification of the most critical areas, but paves the way towards joint and cost-effective adaptation across sectors.

Cutting greenhouse gas emissions aimed at attaining the 2°C target can help maintain the crop yields. The strict emissions cuts can rely on land-based mitigation measures as bioenergy and can compete with food production. Here we explored effects of climate mitigation on food security using multi-economic models. As our results, most of the economic models agreed that the strict emissions cuts aimed at attaining the 2°C target could indirectly lead to more people at risk of hungry than if those cuts weren’t in place. The potential for a sizeable increase in the global risk of hunger in 2 °C scenario was dominated by South Asia and Sub-Saharan Africa where climate mitigation leads additional 10 to 64 and 36 to 116 million people, respectively face at risk of hunger at the intermediate scenario (SSP2) in 2050. We also found that socioeconomic assumptions such as population, economic development and equity of food distribution largely affect the magnitude of increased risk of hunger. That risk doesn't necessarily negate the need for mitigation but highlights the importance of complementary policies, such as increasing food aid, subsidy or food reallocation, when governments address climate change.

This study quantified the impacts of climate change on human health through undernourishment using two economic measures. First, changes in morbidity and mortality due to nine diseases caused by being underweight as a child were analyzed using a Computable General Equilibrium (CGE) model with changes in the labor force, population, and demands for healthcare taken into consideration. Second, changes in mortality were taken from the CGE simulation and assessed economically by the value of lives lost and willingness to pay to reduce the risk. Model uncertainties in future crop yields, climate conditions, and socioeconomic conditions were considered using future projections from six global crop models and five global climate models and assuming multiple socioeconomic conditions. We found that the economic valuation of healthy lives lost due to undernourishment under climate change was equivalent to -0.4% to 0.0% of global gross domestic product (GDP) and was regionally heterogeneous, ranging from -4.0% to 0.0% of regional GDP in 2100. In contrast, the actual economic losses associated with the effects of additional health expenditure and the decrease in the labor force due to undernourishment resulting from climate change corresponded to a -0.1% to 0.0% change in GDP and a -0.2% to 0.0% change in household consumption, respectively, at the global level. These impacts can be avoided by achieving the stringent mitigation in the context of the Paris Agreement.

Terrestrial biodiversity is declining at alarming rate, and the land use and land cover changes are the primary drivers of such trends. This issue is getting increasing attention, for example via the Sustainable Development Goals (SGD15, Life on Land). Over, as illustrated by other SDGs (e.g., SDG2 Zero hunger, SDG6 Clean water and sanitation, or SDG13 Climate Action among others), land use is at the center of many challenges for the coming decades. Increasing our ability to diagnose potential trade-offs between objectives and policies is a key milestone to navigate safely through these challenges. The global change research community recently provided a scenario framework and associated land use change projections quantifying potential trajectories of socioeconomic development (SSPs) and mitigation efforts (RCPs). Although an very preliminary version of such trajectories was translated into terrestrial biodiversity outcomes, the land cover and use projections suffered from many limitations. We will present a new assessment of the terrestrial biodiversity impacts from the new generation of future land use change estimates, at global scale and high resolution. The MESSAGE-GLOBIOM integrated assessment model was used to simulate transitions between individual land cover and uses at high-resolution for a combination of socioeconomic pathways (SSP1, SSP2 and SSP3) and mitigation efforts (RCP1.8, RCP2.6, RCP3.7, RCP4.5, RCP6.0 and no mitigation). The projections were further refined with a downscaling econometric model incorporating most recent land cover change observed from remote-sensing over 1990-2015. These downscaled land cover projections were then interpreted as habitat change and translated into changes in local species richness and global threatened endemic species extinction using a Countryside Species Area Relationship model. We will present the impacts of future land use trajectories under various climate mitigation efforts on local terrestrial biodiversity and global species extinction risk.

Cutting greenhouse gas emissions aimed at attaining the 2°C target can help maintain the crop yields. The strict emissions cuts can rely on land-based mitigation measures as bioenergy and can compete with food production. Here we explored effects of climate mitigation on food security using multi-economic models. As our results, most of the economic models agreed that the strict emissions cuts aimed at attaining the 2°C target could indirectly lead to more people at risk of hungry than if those cuts weren’t in place. The potential for a sizeable increase in the global risk of hunger in 2 °C scenario was dominated by South Asia and Sub-Saharan Africa where climate mitigation leads additional 10 to 64 and 36 to 116 million people, respectively face at risk of hunger at the intermediate scenario (SSP2) in 2050. We also found that socioeconomic assumptions such as population, economic development and equity of food distribution largely affect the magnitude of increased risk of hunger. That risk doesn't necessarily negate the need for mitigation but highlights the importance of complementary policies, such as increasing food aid, subsidy or food reallocation, when governments address climate change.

The 17 Sustainable Development Goals (SDGs) call for a comprehensive new approach to development rooted in planetary boundaries, equity, and inclusivity. The wide scope of the SDGs will necessitate unprecedented integration of siloed policy portfolios to work at international, regional, and national levels toward multiple goals and mitigate the conflicts that arise from competing resource demands. In this analysis, we adopt a comprehensive modeling approach to understand how coherent policy combinations can manage trade-offs among environmental conservation initiatives and food prices. Our scenario results indicate that SDG strategies constructed around Sustainable Consumption and Production policies can minimize problem-shifting, which has long placed global development and conservation agendas at odds. We conclude that Sustainable Consumption and Production policies (goal 12) are most effective at minimizing trade-offs and argue for their centrality to the formulation of coherent SDG strategies. We also find that alternative socioeconomic futures—mainly, population and economic growth pathways—generate smaller impacts on the eventual achievement of land resource–related SDGs than do resource-use and management policies. We expect that this and future systems analyses will allow policy-makers to negotiate trade-offs and exploit synergies as they assemble sustainable development strategies equal in scope to the ambition of the SDGs.

Agriculture plays a key role in achieving adequate food, water, and energy security (as summarized in the Sustainable Development Goals SDGs) as populations grow and incomes rise. Yet, agriculture is confronted with an enormous challenge to produce more, while minimizing increases to the use of and the damages to land and water resources that are projected to be strongly affected by climate change. To formulate policies that contribute to achieving the SDGs, policy makers need assessments that can anticipate and navigate the trade offs within the water/land/energy domain. Assessments that identify locations or hotspots where trade offs between the multiple, competing users of resources may exist must consider both the local scale when examining the impacts of the use of resources as well as role of regional scale socioeconomic trends, policies, and international markets in further contributing to or mitigating the impacts of resource trade offs. In this study, we quantify impacts of increased pressure on the land system to provide agricultural and bioenergy products under increasingly scarce water resources using a global economic and land use model, GLOBIOM. We model the supply and demand of agricultural products at a high spatial resolution in an integrated approach that considers the impacts of global change (socioeconomic and climatic) in the biophysical availability of water and the growing competition for water use, between irrigation on the one hand and other sectors (domestic, energy and industry) as well as freshwater ecosystems (environmental flows). We also developed a biodiversity module that relates changes in land uses to changes in local species richness and global species extinction risk. We find that water available for agriculture and ecosystems decreases due to both climate change and a growing demand from other sectors (Fig 1). Climate change impacts will limit areas suitable for irrigation and may lead to an expansion of rainfed areas in biodiverse areas. Impacts on food security from climate change are significant in some regions (SSA and SA) and policies that protect environmental stream flows compound that effect (Fig 2).