Climate Engineering and Abatement: A ‘flat’ Relationship Under Uncertainty

The potential of geoengineering as an alternative or complementary option to mitigation and adaptation has received increased interest in recent years. The scientific assessment of geoengineering is driven to a large extent by assumptions about its effectiveness, costs, and impacts, all of which are highly uncertain. This has led to a polarizing debate. This paper evaluates the role of Solar Radiation Management (SRM) on the optimal abatement path, focusing on the uncertainty about the effectiveness of SRM and the interaction with uncertain climate change response. Using standard economic models of dynamic decision theory under uncertainty, we show that abatement is decreasing in the probability of success of SRM, but that this relation is concave and thus that significant abatement reductions are optimal only if SRM is very likely to be effective. The results are confirmed even when considering positive correlation structures between the effectiveness of geoengineering and the magnitude of climate change. Using a stochastic version of an Integrated Assessment Model, the results are found to be robust for a wide range of parameters specification

Inequality and growth impacts of climate change—insights from South Africa

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 gross domestic product (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 this paper, we investigate the relationship between temperature and inequality in South Africa at the national and sub-national level. Our analysis reveals a significant ∪-shaped relationship between temperature and inequality indices, with inequality lowest at moderate temperatures (11 ◦C–18 ◦C) and increasing sharply as temperatures increase. We find that the optimal temperatures are lower for inequality measures than for income levels. This indicates that substantial increases in inequality are expected at higher temperatures compared to growth impacts. This effect is particularly noticeable for the poorer segments of the population, whose productivity and wages decline as temperatures increase, while the impact on the richer segments is less significant due to their greater adaptive capacity. In terms of mechanisms, we find that agricultural households are more likely to experience an increase in inequality due to warming. Our findings suggest that global warming has two adverse effects on hot countries: reducing average growth and increasing inequality. We compare the outcomes of the moderate RCP6.0 scenario to a reference scenario without warming and find that by the end of the century, the Gini coefficient in South Africa is expected to increase by 3–6 points, resulting in a potential welfare loss of approximately 50% when combined with the impact of warming on GDP (which alone can reach up to 43% by 2100 in South Africa). Our findings highlight the importance of investigating the distributional effects of climate change at the micro-level, particularly in low- or middle-income countries where vulnerable populations are more susceptible to its impacts

The social cost of carbon with intragenerational inequality and economic uncertainty

An analytical formula is presented for the Social Cost of Carbon (SCC) taking account of intragenerational income inequality, in addition to intergenerational income inequality, macro-economic uncertainty and rare disasters to economic growth. The social discount rate is adjusted for intra- and intergenerational inequality aversion and risk aversion. If growth reduces intragenerational inequality, the SCC is lower than with inequality-neutral growth, especially if intra- and intergenerational inequality aversion are high. Calibrated to the observed interest rate and risk premium, the SCC in 2020 is $125/tCO2 without considering intragenerational inequality,$81/tCO2 if intragenerational inequality decreases over time, as a continuation of historical trends suggests (based on Shared Socioeconomic Pathway (SSP) 2), and $213/tCO2 if inequality increases (SSP4). Intragenerational inequality has a similar order of effect on the SCC as accounting for rare macroeconomic disasters

The social cost of carbon with intragenerational inequality and economic uncertainty

An analytical formula is presented for the Social Cost of Carbon (SCC) taking account of intragenerational income inequality, in addition to intergenerational income inequality, macro-economic uncertainty and rare disasters to economic growth. The social discount rate is adjusted for intra- and intergenerational inequality aversion and risk aversion. If growth reduces intragenerational inequality, the SCC is lower than with inequality-neutral growth, especially if intra- and intergenerational inequality aversion are high. Calibrated to the observed interest rate and risk premium, the SCC in 2020 is $125/tCO2 without considering intragenerational inequality,$81/tCO2 if intragenerational inequality decreases over time, as a continuation of historical trends suggests (based on Shared Socioeconomic Pathway (SSP) 2), and $213/tCO2 if inequality increases (SSP4). Intragenerational inequality has a similar order of effect on the SCC as accounting for rare macroeconomic disasters

Discounting and the representative median agent

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. In a plausible special case the representative agent has the median income. With inequality aversion elasticity of 2 (1.5,1), the U.K. and U.S. SDR would be 1% (0.5%, 0.25%) lower than the standard Ramsey rule. This reects two decades of inequality-increasing growth and implies greater weight placed on future generations in public appraisal

Corporate social and environmental responsibility in India - assessing the UN global compact's role

"This report presents the results of a research project carried out as part of the postgraduate training course of the German Development Institute (GDI), Bonn, in close cooperation with the Centre for Social Markets, India, and with the support of Ashok V. Desai, Consultant Editor of the Telegraph, India. The report is based on studies of the literature and on empirical data collected in India’s main industrial districts of Delhi, Mumbai, Pune, Bangalore and Chennai from February to April 2006. The GDI research team would like to thank Sachin Joshi of the Centre for Social Markets and Ashok V. Desai for their strong scientific and technical support, without which this study would not have been possible. The research team would also like to express their thanks to the top officials of almost 40 Indian and foreign companies and 32 other stakeholders who spoke of their experience and responded to our questionnaire on CSR in India and the role of the UN Global Compact in particular. Last but not least, the authors are very grateful to experts from other Indian, international and German institutions who were kind enough to share their knowledge with us and so contributed to the writing of the report. However, the GDI team alone is responsible for the results presented here." (excerpt)Der vorliegende Beitrag untersucht die UN Global Compact-Initiative (UNGC), die im Jahr 2000 von dem damaligen UN-Generalsekretär Kofi Annan aus der Taufe gehoben wurde, unter besonderer Berücksichtigung der sozialen und ökologischen Aktivitäten in Indien. Der Global Compact, ein weltweiter Pakt, der zwischen Unternehmen und der UNO geschlossen wird, basiert auf zehn Prinzipien, die der Einhaltung bestimmter sozialer und ökologischer Mindeststandards dienen. Dies sind beispielsweise die wesentlichen Konventionen zur Einhaltung der Menschenrechte, Vereinigungsfreiheit, keine Zwangsarbeit, keine Kinderarbeit, Nicht-Diskriminierung, wesentliche Prinzipien, wie sie in den Rio-Konventionen zum Umweltschutz verfasst worden sind, sowie das Prinzip gegen alle Formen von Korruption. (ICD2

Exciton-polaritons in flatland : controlling flatband properties in a Lieb lattice

Funding: T.H.H., J.B., P.G., J.M., M.E., C.S., S.H., and S.K. acknowledge financial support by the German Research Foundation (DFG) under Germany’s Excellence Strategy–EXC2147 “ct.qmat” (project id 390858490). S.K., J.B., U.P., and O.A.E. acknowledge support by the German Research Foundation (DFG) within project KL2431/2-1. S.H. is furthermore grateful for support within the EPSRC Hybrid Polaritonics Grant (Grant No. EP/M025330/1). T.H.H. and S.H. acknowledge funding by the doctoral training program Elitenetzwerk Bayern Graduate School “Topological insulators.” T.H.H. acknowledges support by the German Academic Scholarship Foundation.In recent years, novel two-dimensional materials such as graphene, bismuthene, and transition-metal dichalcogenides have attracted considerable interest due to their unique physical properties. However, certain lattice geometries, such as the Lieb lattice, do not exist as atomic monolayers. Fortunately, a range of physical effects can be transferred to the realms of photonics by creating artificial photonic lattices emulating these two-dimensional materials. Here, exciton-polaritons in semiconductor microcavities offer an exciting opportunity to study a part-light, part-matter quantum fluid of light in a complex lattice potential. In this Rapid Communication, we study exciton-polaritons in a two-dimensional Lieb lattice of buried optical traps. The S and Pxy photonic orbitals of such a Lieb lattice give rise to the formation of two flatbands which are of greatest interest for the distortion-free storage of compact localized states. By using a well controlled etch-and-overgrowth technique, we manage to control the trapping as well as the site couplings with great precision. This allows us to spectroscopically monitor the flatness of the flatbands across the full Brillouin zone. Furthermore, we demonstrate experimentally that these flatbands can be directly populated by condensation under nonresonant laser excitation. Finally, using this advanced device approach we demonstrate resonant and deterministic excitation of flatband modes in transmission geometry. Our findings establish the exciton-polariton systems as a highly controllable, optical many-body system to study flatband effects and for distortion-free storage of compact localized states.Publisher PDFPeer reviewe