Johannes Emmerling

RFF-CMCC European Institute on Economics and the Environment · SEME

We propose a robust risk management approach to deal with the problem of catastrophic climate change that incorporates both risk and model uncertainty. Using an analytical model of abatement, we show how aversion to model uncertainty influences the optimal level of mitigation. We disentangle the role of preferences from the structure of model uncer...

We derive a simple formula for the social discount rate (SDR) that uses the median, rather than average agent of the economy to reflect the consequences of consumption growth on income inequality. Under reasonable assumptions, the difference between the growth of median and mean incomes is used to adjust the wealth-effect in the standard Ramsey rul...

Hopes are high that removing fossil fuel subsidies could help to mitigate climate change by discouraging inefficient energy consumption and levelling the playing field for renewable energy. In September 2016, the G20 countries re-affirmed their 2009 commitment (at the G20 Leaders' Summit) to phase out fossil fuel subsidies and many national governm...

Equity (or, its counterpart, inequity) plays a fundamental role in the evaluation of social welfare in different dimensions. In this paper, we revisit the concept of inequity – in the sense of unequal distributions – across individuals, time, and states of the world using a unified framework that generalizes the standard expected discounted utilita...

We present a novel way to disentangle inequality aversion over time from inequality aversion between regions in the computation of the social cost of carbon. Our approach nests a standard efficiency based estimate and an equity weighted estimate as special cases. We use two integrated assessment models (FUND and RICE) to present quantitative estima...

Concerns have been raised against using carbon pricing for fighting climate change, as these might disproportionally affect lower-income households and thus increase inequality. However, the distributional implications of climate policies will depend on policy design and their capacity to reduce climate change impacts. To quantify the interaction b...

Negative emissions technologies are attracting the interest of investors in the race to make them effective and profitable. When deployed at scale, they will be financed through public funds, reducing the fiscal space for a socially inclusive climate transition. Moreover, if the private sector owns negative emissions technologies, potentially large...

Energy models are used to study emissions mitigation pathways, such as those compatible with the Paris Agreement goals. These models vary in structure, objectives, parameterization and level of detail, yielding differences in the computed energy and climate policy scenarios. To study model differences, diagnostic indicators are common practice in m...

The impact of climate change on economic growth has been the subject of numerous studies in recent years, with macro-econometric analyses estimating the effect of rising temperatures on GDP growth rates at the country-level. However, the distributional impact of warming on inequality and poverty at the micro-level remains relatively unexplored. In...

Geoengineering, including solar radiation management (SRM), has received increasing scrutiny due to the rise of climate extremes and slow progress in mitigating global carbon emissions. This climate policy option, even as a possibility, can have consequential implications for international climate governance. Here, we study how solar engineering af...

In recent years, the decarbonisation of international shipping has become an important policy goal. While Integrated Assessment Models (IAMs) are often used to explore climate mitigation strategies, they typically provide little information on international shipping, which accounts for around 0.75 GtCO 2 /yr. Here, we perform the first multi-IAM an...

Economic analyses of global climate change have been criticized for their poor representation of climate change damages. Here we develop and apply aggregate damage functions in three economic Integrated Assessment Models (IAMs) with different degrees of complexity. The damage functions encompass a wide but still incomplete set of climate change imp...

Energy models are used to study mitigation pathways compatible with the Paris Agreement goals. These models vary in structure, objectives, parameterization, and level of detail, which yield differences in the computed mitigation pathways. To interpret model differences, diagnostic indicators are already common practice in many scientific fields, e....

Climate adaptation actions can be energy-intensive, but how adaptation feeds back into the energy system and the environment is absent in nearly all up-to-date energy scenarios. Here we quantify the impacts of adaptation actions entailing direct changes in final energy use on energy investments and costs, greenhouse gas emissions, and air pollution...

Negative emission technologies are attracting the interest of investors in the race to make them effective and profitable. When deployed at scale, negative emissions will need to be financed through carbon tax revenues or issuing other taxes. Financing negative emissions could thus reduce the fiscal resources needed for a socially inclusive transit...

Projections of energy intensity are important for the assessment of future energy demand, future emission pathways, and the costs of climate policies. We estimate and simulate energy intensity based on a conditional convergence approach, and show how based on the results the long-run minimum of energy intensity attainable can be estimated. We consi...

International migration is closely tied to demographic, socioeconomic, and environmental factors and their interaction with migration policies. Using a combination of a gravity econometric model and an overlapping generations model, we estimate the probability of bilateral migration among 160 countries in the period of 1960 to 2000 and use these fi...

Delaying climate mitigation action and allowing a temporary overshoot of temperature targets require large-scale carbon dioxide removal (CDR) in the second half of this century that may induce adverse side effects on land, food and ecosystems. Meanwhile, meeting climate goals without global net-negative emissions inevitably needs early and rapid em...

Mitigation pathways exploring end-of-century temperature targets often entail temperature overshoot. Little is known about the additional climate risks generated by overshooting temperature. Here we assessed the benefits of limiting overshoot. We computed the probabilistic impacts for different warming targets and overshoot levels on the basis of a...

We estimate the impact of a large number of determinants of subjective well-being (SWB) across 143 countries, and project SWB across macro-regions for different socio-economic scenarios. We focus on the 23% of the variance in SWB that is explained by cross-country differences, as the remaining 77% is due to individual-specific factors. We estimate...

The consensus view amongst economists is that carbon prices, in order to be effcient, must be the same across the globe. But when there are inefficiencies in the allocation of capital so that consumers in different countries face different discount rates, we show that efficient carbon prices must be different across countries. This is a consequence...

The Paris Agreement does not only stipulate to limit the global average temperature increase to well below 2 °C, it also calls for 'making finance flows consistent with a pathway towards low greenhouse gas emissions'. Consequently, there is an urgent need to understand the implications of climate targets for energy systems and quantify the associat...

To limit global warming to well-below 2°C (WB2C), fossil fuels must be replaced by low-carbon energy sources. Support for this transition is often dampened by the impact on fossil fuel jobs. Previous work shows that pro-climate polices could increase employment by 20 million net energy jobs, but these studies rely on Organisation for Economic Co-op...

Benefit-cost analyses of climate policies by integrated assessment models have generated conflicting assessments. Two critical issues affecting social welfare are regional heterogeneity and inequality. These have only partly been accounted for in existing frameworks. Here, we present a benefit-cost model with more than 50 regions, calibrated upon e...

Estimates of climate change’s economic impacts vary widely, depending on the applied methodology. This uncertainty is a barrier for policymakers seeking to quantify the benefits of mitigation. In this Perspective, we provide a comprehensive overview and categorization of the pathways and methods translating biophysical impacts into economic damages...

Integrated assessment models (IAMs) have emerged as key tools for building and assessing long term climate mitigation scenarios. Due to their central role in the recent IPCC assessments, and international climate policy analyses more generally, and the high uncertainties related to future projections, IAMs have been critically assessed by scholars...

Integrated assessment models (IAMs) form a prime tool in informing about climate mitigation strategies. Diagnostic indicators that allow comparison across these models can help describe and explain differences in model projections. This increases transparency and comparability. Earlier, the IAM community has developed an approach to diagnose models...

The threat of climate catastrophes has been shown to radically change optimal climate policy and prospects for international climate agreements. We characterize the strategic behavior in emissions mitigation and agreement participation with a potential climate catastrophe happening at a temperature threshold. Players are heterogeneous in a conceptu...

Climate change affects human and natural systems unevenly. Solving it, by reducing greenhouse gases and adapting to climate impacts, will also be felt differently depending on levels of income and other dimensions of inequality. This leads us to ask: have the widely used integrated assessment models accommodated inequality considerations sufficient...

The COVID-19 pandemic has affected households across the globe due to the health impacts but also through indirect socioeconomic effects as a result of the additional stress on the health systems, implications of the lockdowns and other policy measures undertaken by governments. Moreover, there is evidence that these impacts are associated with soc...

The COVID-19 pandemic, lock-down restrictions and other measures that have been put in place have potentially far reaching implications for inequality within and between countries, for energy demand in different sectors, and for structural change and economic growth. These factors are highly relevant for climate action. In response to the COVID-19...

Allowing delayed climate mitigation actions and overshoot of temperature targets requires large scale negative carbon emissions that may induce adverse side-effects on land, food and ecosystems in the second half of this century. Meanwhile, meeting climate goals without net negative emissions inevitably needs the implementation of early and quick e...

The bottom-up approach of the Nationally Determined Contributions (NDCs) in the Paris Agreement has led countries to self-determine their greenhouse gas (GHG) emission reduction targets. The planned ‘ratcheting-up’ process, which aims to ensure that the NDCs comply with the overall goal of limiting global average temperature increase to well below...

Cost-effective achievement of the Paris Agreement's long-term goals requires the unanimous phase-out of coal power generation by mid-century. However, continued investments in coal power plants will make this transition difficult. India is one of the major countries with significant under construction and planned increase in coal power capacity. To...

International efforts to avoid dangerous climate change aim for large and rapid reductions of fossil fuel CO2 emissions worldwide, including nearly complete decarbonization of the electric power sector. However, achieving such rapid reductions may depend on early retirement of coal- and natural gas-fired power plants. Here, we analyze future fossil...

Many countries have implemented national climate policies to accomplish pledged Nationally Determined Contributions and to contribute to the temperature objectives of the Paris Agreement on climate change. In 2023, the global stocktake will assess the combined effort of countries. Here, based on a public policy database and a multi-model scenario a...

Many countries have implemented national climate policies to accomplish pledged Nationally Determined Contributions and to contribute to the temperature objectives of the Paris Agreement on climate change. In 2023, the global stocktake will assess the combined effort of countries. Here, based on a public policy database and a multi-model scenario a...

The entire agricultural supply chain, from crop production to food consumption, is expected to suffer significant damages from climate change. This paper empirically investigates the effects of warming on agricultural labor supply through variation in dietary intake in rural Uganda. We examine labor supply, food consumption, and overall social welf...

The importance of the discount rate in cost-benefit analysis of long term problems, such as climate change, has been widely acknowledged. However, the choice of the discount rate is hardly discussed when translating policy targets –such as 1.5 and 2°C– into emission reduction strategies with the possibility of overshoot. Integrated assessment model...

Holding the global increase in temperature caused by climate change well below 2 °C above pre-industrial levels, the goal affirmed by the Paris Agreement, is a major societal challenge. Meanwhile, food security is a high-priority area in the UN Sustainable Development Goals, which could potentially be adversely affected by stringent climate mitigat...

Growing concerns about climate change impacts on humans and ecosystems motivates exploring new strategies to complement traditional climate policies like mitigation and adaptation. Climate engineering via solar radiation management is one discussed option. However, climate engineering entails new risks, including its governance. Without sufficientl...

Future socioeconomic developments and climate policies will play a role in air quality improvement since greenhouse gases and air pollutant emissions are highly connected. As these interactions are complex, air quality indices are useful tools to assess the sustainability of future policies. Here, we compute new global annual air quality indices to...

In the version of ‘Supplementary Data 1’ originally published with this Article, the units for the ‘Capacity|Electricity|*’ variables in the ‘Non_Investment_Annual’ tab were incorrectly given as EJ/yr; they should have read GW. This has now been corrected. Also, some of the variables listed in the ‘Non_Investment_Variable_Defs’ were not required an...

Burgeoning demands for mobility and private vehicle ownership undermine global efforts to reduce energy-related greenhouse gas emissions. Advanced vehicles powered by low-carbon sources of electricity or hydrogen offer an alternative to conventional fossil-fuelled technologies. Yet, despite ambitious pledges and investments by governments and autom...

Low-carbon investments are necessary for driving the energy system transformation that is called for by both the Paris Agreement and Sustainable Development Goals. Improving understanding of the scale and nature of these investments under diverging technology and policy futures is therefore of great importance to decision makers. Here, using six gl...

The Paris Agreement—which is aimed at holding global warming well below 2 °C while pursuing efforts to limit it below 1.5 °C—has initiated a bottom-up process of iteratively updating nationally determined contributions to reach these long-term goals. Achieving these goals implies a tight limit on cumulative net CO2 emissions, of which residual CO2...

Abstract Projections of energy demand or intensity are important for the assessment of future emission pathways, and the potential and costs of climate policies. Moreover, they provide one of the most crucial calibration issues for energy-economy models. We estimate and simulate energy intensity based on alternatively a panel regression and a condi...

Climate change impacts are stochastic and highly uncertain and moreover heterogeneous across regions. That is, there is a potential to sharing this risk ex-ante across regions and hence to reduce the welfare-economic costs of these risks. We analyze how climate risks could be reduced via an insurance scheme at the global scale across regions and qu...

Climate engineering, and in particular solar radiation management (SRM), is attracting increasing attention as a climate policy option. However, its potentially strategic nature and unforeseen side effects provide major policy and scientific challenges. We study the role of SRM in a two-country model with the notable feature of deep uncertainty mod...

Carbon capture and sequestration (CCS) is considered a key technology for stabilizing climate change. However, leakage of CO2 from stored carbon can potentially undermine the value of carbon storage as a mitigation option. Thus, monitoring and verifiability of CO2 storage should be encouraged through policy provisions such as accounting and pricing...

The 2015 Paris Agreement calls for countries to pursue efforts to limit global-mean temperature rise to 1.5 °C. The transition pathways that can meet such a target have not, however, been extensively explored. Here we describe scenarios that limit end-of-century radiative forcing to 1.9 W/ m2, and consequently restrict median warming in the year 21...

We study the optimal consumption discount rate taking into account income inequality within a generation between countries. We show that if the dispersion of income decreases over time, the global consumption discount rate should under certain conditions be lower than in the case without inequality. Using actual growth predictions used in the conte...

The potential of climate engineering to substitute or complement abatement of greenhouse gas emissions has been increasingly debated over the last years. The scientific assessment is driven to a large extent by assumptions regarding its effectiveness, costs, and impacts, all of which are profoundly uncertain. We investigate how this uncertainty abo...

The mismatch between actions to combat climate change, which are based on voluntary national initiatives of limited effort, and the recognition of the importance of global warming is growing. Climate engineering via solar radiation management has been proposed as a possible complement to traditional climate policies. However, climate engineering en...

We derive a simple formula for the social discount rate (SDR) that uses the median, rather than average agent of the economy to reect the consequences of consumption growth on income inequality. Under reasonable assumptions, the difference between the growth of median and mean incomes is used to adjust the wealth-effect in the standard Ramsey rule....

The Paris Agreement has set stringent temperature targets to limit global warming to 2°C above preindustrial level, with efforts to stay well below 2°C. At the same time, its bottom-up approach with voluntary national contributions makes the implementation of these ambitious targets particularly challenging. Climate engineering –both through carbon...

Using panel data from the UK, we study the long-term effect of purchase decisions of automobiles on individuals' happiness. We find a significant and sizable decrease in individual happiness in the years after a car purchase. We develop a model of hedonic adaptation that can explain these results. Applying the model to the data indicates a strong d...