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- ItemOptimal carbon taxation and horizontal equity: A welfare-theoretic approach with application to German household data(Amsterdam : Elsevier, 2022) Hänsel, Martin C.; Franks, Max; Kalkuhl, Matthias; Edenhofer, OttmarWe develop a model of optimal taxation and redistribution under an ambitious climate target. We take into account vertical income differences, but also explicitly capture horizontal equity concerns by considering heterogeneous energy efficiencies. By deriving first- and second-best rules for policy instruments including carbon and labor taxes, transfers and energy subsidies, we investigate analytically how vertical and horizontal inequality is considered in the welfare maximizing tax structure. We calibrate the model to German household data and a 30 percent emission reduction goal and show that redistribution of carbon tax revenues via household-specific transfers is the first-best policy. Under plausible assumptions on inequality aversion, transfers to energy-intensive households should be about five times higher than transfers to energy-efficient households. Equal per-capita transfers do not require to observe households’ efficiency type, but increase equity-weighted mitigation costs by around 5 percent compared to the first-best. Mitigation costs increase by less, if the government can implement a uniform clean energy subsidy or household-specific tax-subsidy schemes on energy consumption and labor income that target heterogeneous energy efficiencies. Horizontal equity concerns may therefore constitute a new second-best rationale for clean energy policies or differentiated energy taxes.
- ItemBiodiversity research: Data without theory-theory without data(Lausanne : Frontiers Media, 2015) Rillig, Matthias C.; Kiessling, Wolfgang; Borsch, Thomas; Gessler, Arthur; Greenwood, Alex D.; Hofer, Heribert; Joshi, Jasmin; Schröder, Boris; Thonicke, Kirsten; Tockner, Klement; Weisshuhn, Karoline; Jeltsch, Florian[No abstract available]
- ItemThe impact of climate conditions on economic production. Evidence from a global panel of regions(Amsterdam [u.a.] : Elsevier, 2020) Kalkuhl, Matthias; Wenz, LeonieWe present a novel data set of subnational economic output, Gross Regional Product (GRP), for more than 1500 regions in 77 countries that allows us to empirically estimate historic climate impacts at different time scales. Employing annual panel models, long-difference regressions and cross-sectional regressions, we identify effects on productivity levels and productivity growth. We do not find evidence for permanent growth rate impacts but we find robust evidence that temperature affects productivity levels considerably. An increase in global mean surface temperature by about 3.5°C until the end of the century would reduce global output by 7–14% in 2100, with even higher damages in tropical and poor regions. Updating the DICE damage function with our estimates suggests that the social cost of carbon from temperature-induced productivity losses is on the order of 73–142$/tCO2 in 2020, rising to 92–181$/tCO2 in 2030. These numbers exclude non-market damages and damages from extreme weather events or sea-level rise. © 2020 The Authors
- ItemChanging seasonal temperature offers a window of opportunity for stricter climate policy(Amsterdam [u.a.] : Elsevier Science, 2022) Pfeifer, Lena; Otto, Ilona M.Environmental catastrophes, including the increased severity and frequency of climate extremes, can act as “windows of opportunities” that challenge citizens’ mental models and motivate them to engage in reflective processes, challenging their pre-conceived ideas. Less well understood is whether experiencing changing weather conditions, common in mid-latitudes, can have a similar effect and increase the citizens’ concerns about climate change and their willingness to accept more stringent climate policies. In this paper, we investigate the effects of changing seasonal temperature on the perceived seriousness of climate change and willingness to mitigate climate change. We use data from four yearly waves of a spatially explicit representative population survey in Germany and weather records from the postal code areas in which they live. To our knowledge, this study is the first analysis to link individual perceptions towards climate change and different mitigation options with seasonal temperature changes at specific locations in Europe. The analyzed perceptions were strongly influenced by socio-demographic characteristics and broader societal changes, as well as individual experiences of seasonal temperatures. The results show that experienced seasonal temperature change influences personal climate change concerns as well as the willingness to mitigate climate change, although with a weaker effect. The results indicate that it is the absolute temperature variation experienced that is important, rather than whether it is getting colder or warmer than usual. Considering the influences identified in this study can offer a window of opportunity for more stringent and targeted climate change policy.
- ItemCan Tanzania’s adaptation measures prevent future maize yield decline? A simulation study from Singida region(Berlin ; Heidelberg ; New York : Springer, 2021) Volk, Johanna; Gornott, Christoph; Sieber, Stefan; Lana, Marcos AlbertoCereal crop production in sub-Saharan Africa has not achieved the much-needed increase in yields to foster economic development and food security. Maize yields in the region’s semi-arid agroecosystems are constrained by highly variable rainfall, which may be worsened by climate change. Thus, the Tanzanian government has prioritized agriculture as an adaptation sector in its intended nationally determined contribution, and crop management adjustments as a key investment area in its Agricultural Sector Development Programme. In this study, we investigated how future changes in maize yields under different climate scenarios can be countered by regional adjusted crop management and cultivar adaptation strategies. A crop model was used to simulate maize yields in the Singida region of Tanzania for the baseline period 1980–2012 and under three future climate projections for 2020–2060 and 2061–2099. Adaptation strategies to improve yields were full irrigation, deficit irrigation, mulch and nitrogen addition and another cultivar. According to our model results, increase in temperature is the main driver of future maize yield decline. Increased respiration and phenological development were associated with lower maize yields of 16% in 2020–2060 and 20% in 2061–2099 compared to the 1980–2012 baseline. Surprisingly, none of the management strategies significantly improved yields; however, a different maize variety that was tested as an alternative coping strategy performed better. This study suggests that investment in accessibility of improved varieties and investigation of maize traits that have the potential to perform well in a warmer future are better suited for sustaining maize production in the semi-arid region than adjustments in crop management.
- ItemWarming assessment of the bottom-up Paris Agreement emissions pledges([London] : Nature Publishing Group UK, 2018) Robiou du Pont, Yann; Meinshausen, MalteUnder the bottom-up architecture of the Paris Agreement, countries pledge Nationally Determined Contributions (NDCs). Current NDCs individually align, at best, with divergent concepts of equity and are collectively inconsistent with the Paris Agreement. We show that the global 2030-emissions of NDCs match the sum of each country adopting the least-stringent of five effort-sharing allocations of a well-below 2 °C-scenario. Extending such a self-interested bottom-up aggregation of equity might lead to a median 2100-warming of 2.3 °C. Tightening the warming goal of each country’s effort-sharing approach to aspirational levels of 1.1 °C and 1.3 °C could achieve the 1.5 °C and well-below 2 °C-thresholds, respectively. This new hybrid allocation reconciles the bottom-up nature of the Paris Agreement with its top-down warming thresholds and provides a temperature metric to assess NDCs. When taken as benchmark by other countries, the NDCs of India, the EU, the USA and China lead to 2.6 °C, 3.2 °C, 4 °C and over 5.1 °C warmings, respectively.
- ItemResponsibility Under Uncertainty: Which Climate Decisions Matter Most?(Amsterdam : Baltzer Science Publ., 2023) Botta, Nicola; Brede, Nuria; Crucifix, Michel; Ionescu, Cezar; Jansson, Patrik; Li, Zheng; Martínez, Marina; Richter, TimWe propose a new method for estimating how much decisions under monadic uncertainty matter. The method is generic and suitable for measuring responsibility in finite horizon sequential decision processes. It fulfills “fairness” requirements and three natural conditions for responsibility measures: agency, avoidance and causal relevance. We apply the method to study how much decisions matter in a stylized greenhouse gas emissions process in which a decision maker repeatedly faces two options: start a “green” transition to a decarbonized society or further delay such a transition. We account for the fact that climate decisions are rarely implemented with certainty and that their consequences on the climate and on the global economy are uncertain. We discover that a “moral” approach towards decision making — doing the right thing even though the probability of success becomes increasingly small — is rational over a wide range of uncertainties.
- ItemEurope’s renewable energy directive poised to harm global forests([London] : Nature Publishing Group UK, 2018) Searchinger, Timothy D.; Beringer, Tim; Holtsmark, Bjart; Kammen, Daniel M.; Lambin, Eric F.; Lucht, Wolfgang; Raven, Peter; van Ypersele, Jean-PascalThis comment raises concerns regarding the way in which a new European directive, aimed at reaching higher renewable energy targets, treats wood harvested directly for bioenergy use as a carbon-free fuel. The result could consume quantities of wood equal to all Europe’s wood harvests, greatly increase carbon in the air for decades, and set a dangerous global example.
- ItemGerman pig farmers’ perceived agency under different nitrogen policies(Bristol : IOP Publishing, 2021) Stuhr, Luisa; Bodirsky, Benjamin Leon; Jaeger-Erben, Melanie; Beier, Felicitas; Hunecke, Claudia; Collignon, Quitterie; Lotze-Campen, HermannAgricultural nitrogen (N) emissions represent the most substantial N source in Germany. Even though multiple policies have been introduced at the EU and German national level to reduce agriculturally sourced reactive Nitrogen (N), Germany is exceeding the target of the government's national sustainability strategy to limit N surpluses. To form a better view of the current N policy challenges, this paper seeks to identify what constrains family-managed pig farmers in Germany from adopting N-reduced farming practices. Our study applies a practice-based approach and reconstructs farmers' practice and individual perception of the possible capability to change practices (perceived agency) through problem-centred interviews. The study identifies different ideal types of farmers based on their reported farming practices and perceived agency: The first type feeling overburdened and weary of the current requirements, the second type acting based on routine and incremental improvement efforts, and the third type adapting early and inventing. However, regarding the perceived agency to adopt N-reduced farming practices our results show that all three farmer types report only low to little agency. Based on the findings, the study identifies type-specific and type-spanning constraining factors. To resolve farmers' perceived contradictions and inconsistencies which result in the unwillingness to accept further N reduction measures, we argue that policies need to address these factors. To enhance long-term paths for sustainable N-reduced farming practices, this study concludes that N policies need to shift towards outcome-oriented policies to create a collective and holistic understanding of the desired outcome while considering their embeddedness into regional and individual contexts.
- ItemFood Surplus and Its Climate Burdens(Columbus, Ohio : American Chemical Society, 2016) Hiç, Ceren; Pradhan, Prajal; Rybski, Diego; Kropp, Jürgen P.Avoiding food loss and waste may counteract the increasing food demand and reduce greenhouse gas (GHG) emissions from the agricultural sector. This is crucial because of limited options available to increase food production. In the year 2010, food availability was 20% higher than was required on a global scale. Thus, a more sustainable food production and adjusted consumption would have positive environmental effects. This study provides a systematic approach to estimate consumer level food waste on a country scale and globally, based on food availability and requirements. The food requirement estimation considers demographic development, body weights, and physical activity levels. Surplus between food availability and requirements of a given country is considered as food waste. The global food requirement changed from 2,300 kcal/cap/day to 2,400 kcal/cap/day during the last 50 years, while food surplus grew from 310 kcal/cap/day to 510 kcal/cap/day. Similarly, GHG emissions related to the food surplus increased from 130 Mt CO2eq/yr to 530 Mt CO2eq/yr, an increase of more than 300%. Moreover, the global food surplus may increase up to 850 kcal/cap/day, while the total food requirement will increase only by 2%–20% by 2050. Consequently, GHG emissions associated with the food waste may also increase tremendously to 1.9–2.5 Gt CO2eq/yr.