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Hamburg Climate Futures Outlook 2021. Assessing the plausibility of deep decarbonization by 2050

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In the annual Hamburg Climate Futures Outlook, CLICCS researchers make the first systematic attempt to assess which climate futures are plausible, by combining multidisciplinary assessments of plausibility. The inaugural 2021 Hamburg Climate Futures Outlook addresses the question: Is it plausible that the world will reach deep decarbonization by 2050?
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... This study focused on the Hamburg metropolitan area. The Hamburg area is one of the few areas in Germany where the predicted impact of extreme weather events such as droughts and heat waves in even the most extreme IPCC scenarios is tempered compared to more southern and inland regions in Germany [36]. This gives us the opportunity to look at forest growth relatively unentangled from future climate scenarios. ...
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As various political initiatives have set goals to reach net-zero emissions by the mid-21st century, forests will play an important role as a carbon sink for sequestering unavoidable emissions. Forest management can take two approaches by either decreasing harvest and enlarging the forest carbon stock or increasing harvest to increase carbon uptake and create harvested wood products (HWPs). Currently, these two management options seem at odds with seemingly conflicting policy directives being written. We used the BEKLIFUH model to assess six management scenarios based on carbon offset potential taking into consideration forest carbon, HWPs and the material and energetic substitution effects. The results show that while conservation leads to a higher above-ground carbon pool, including HWPs, material and energetic substitution leads to more overall carbon offsets for management scenarios with more timber harvesting. With compromise being possible by selectively conserving old growth forests with a high biodiversity value. In conclusion, if the forest sector decouples GHG reporting from forest management and includes all the secondary effects of timber harvest, this new approach can lead to a different cost–benefit analysis for the choice between harvest vs. conservation. This could result in a paradigm shift to a future where biodiversity and carbon neutrality can coexist.
... However, while ensuing results are possible from a purely techno-economic viewpoint, they may not be plausible from a wider societal stance once further frictions stemming from behavioural effects, gradual innovation processes, and path-dependent technology diffusion are accounted for (Cherp et al., 2018;Mercure et al., 2019;Trutnevyte et al., 2019). For example, a recent report argued that 'limiting global surface warming below about 1.7 • C by 2100 is currently not plausible' due to such constraints (Stammer et al., 2021). Scenarios that explore non-idealised emission pathways are therefore often informed by narratives about societal developments such as the shared socio-economic pathways (SSPs) (O'Neill et al., 2014), yet seldom endogenised. ...
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Transforming global energy systems is critical for climate change mitigation and requires overcoming not only techno-economic, but also socio-technical hurdles. The main tools to analyse challenges in these two domains are integrated assessment models (IAMs) and transition theories or models, respectively. Despite a surging interest in integrative research that leverages complementarities in order to include social constraints into IAMs, both approaches are often confined to their own disciplinary background and practical integration studies of existing models are scarce. Here I demonstrate the feasibility of model integration by a bi-directional soft-link that merges the strengths of a neoclassical intertemporally optimising IAM with one global region, and a technologically and regionally highly resolved, evolutionary simulation model of S-shaped technology diffusion in the power sector. The new model iteratively converges to a stable equilibrium via two time-dependent coupling variables: carbon prices and renewable energy shares. The results for a 2 °C2∘ C scenario show that due to gradual technology diffusion, energy transition challenges are exacerbated and incur higher economic losses. I discuss the potential of coupling existing models as an option to combine insights from different disciplinary perspectives to energy transitions.
... Although many countries have pledged to reduce their emissions to net zero by 2050 or 2060, much stronger commitments are required-staying below 1.5°C requires almost halving emissions within 8 years (UNEP 2021;UNFCCC 2021;Climate Action Tracker 2021). The feasibility of current efforts is also problematic: Liu and Raftery (2021) argue that national goals will probably not be met, and analysis concludes that deep decarbonization by 2050 is not likely (Stammer et al. 2021). ...
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The Paris targets are based on assumptions that a global temperature increase of 1.5°C - 2°C above preindustrial levels will be safe, and that the climate can be stabilized at these higher temperatures. However, global average temperatures are already measurably impacting the Earth’s systems at 1.2°C above preindustrial levels. Many human and environmental systems cannot adapt to higher temperatures, which may exceed critical tipping points in physical climate and ecological systems. Compounding these risks is the likelihood that the international 2°C limit will be overshot due to political obstacles and systemic inertia from existing greenhouse gases, warming oceans, and the decades required to replace existing infrastructure. Moreover, the Earth energy imbalance may have to be reduced to approximately zero to stabilize the global climate (i.e., CO2 concentrations lowered to around 350 ppm.) Most IPCC mitigation scenarios assume that climate targets will be temporarily overshot, and require large-scale carbon dioxide removal [CDR] to subsequently lower temperatures. However, many CDR methods may not be politically and/or technologically feasible, and they will act too slowly to prevent dangerous overshoot. These issues raise serious doubts about the ability of current mitigation polices to ensure safe outcomes. They also indicate the need to investigate whether rapid climate cooling measures may be required to reduce the risks associated with high temperatures during the long time it will take to decarbonize the global economy and stabilize the climate. Given the uncertainty of future mitigation success, and the potentially existential costs of failure, there is now an urgent need to examine whether or not current efforts are credible, and if not, what mitigation measures will be required to prevent dangerous overshoot and ensure a safe, stable climate. In order to develop a feasible mitigation strategy, it will be necessary to prioritize research both on climate overshoot risks, and on the relative effectiveness, risks, costs and timelines of potential mitigation and adaptation approaches. Since large scale climate interventions will be needed to prevent dangerous global warming, all plausible options need to be investigated, including carbon dioxide removal methods and technologies for rapidly cooling global temperatures. This research is a prerequisite for evaluating the comparative benefits, costs and risks of using, or not using, various forms of mitigation and adaptation, and then developing a realistic overshoot risk management plan.
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The concluding chapter summarizes the main findings of the book, particularly its argument that the fragmentation and contestation of political discourse about climate change, and differences in the political space as the framework of relevant issue dimensions are key factors for explaining the divergence of climate policy-making in the EU and US. Contextualizing these findings with current political developments and addressing future research agendas, the final part highlights two points: first, the relevance of issue linkages and processes of re-framing climate action in relation to other fields of policy-making, as observed in the launch of programs for the economic recovery from the COVID-19 pandemic, and from shifts in the debate on climate and energy policy resulting from the war in Ukraine; and second, the current dynamic of politicization of climate governance, understood as a term for the expansion of relevant public debate in terms of its scope, visibility and contentiousness. The chapter concludes by discussing how a research agenda focused on discourse and framing can contribute to our future understanding of these two key dynamics of controversy on climate change governance.
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This article addresses the broader question of the special issue by reflecting on the coloniality of knowledge production in a context of global climate governance. We highlight key dynamics in which knowledge shapes climate policies and propose a decolonial approach at the nexus of academic knowledge production and policy formation by accounting for diverse ways of knowing climate justice. The article asks how to develop a decolonial approach to researching climate justice in order to identify the meaning-in-use of climate justice by affected people in what we describe as sensitive regions of the Arctic and the Mediterranean. To this end, the article proposes a research design that accounts for diverse ways of knowing and proceeds as follows: first, we will discuss how diverse ways of knowing are related to global climate governance and climate justice; second, we outline our practicebased research framework that addresses research ethics, decolonial approaches and norm contestation; and third, we discuss how our approach can inform not only the co-production of research in climate governance, but also current debates on climate justice.
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International surveys suggest people increasingly agree the climate is changing and humans are the cause. One reading of this is that people have adopted the scientific point of view. Based on a sample of 28 ethnographic cases we argue that this conclusion might be premature. Communities merge scientific explanations with local knowledge in hybrid ways. This is possible because both discourses blame humans as the cause of the changes they observe. However, the specific factors or agents blamed differ in each case. Whereas scientists identify carbon dioxide producers in particular world regions, indigenous communities often blame themselves, since, in many lay ontologies, the weather is typically perceived as a local phenomenon, which rewards and punishes people for their actions. Thus, while survey results show approval of the scientific view, this agreement is often understood differently and leads to diverging ways of allocating meaning about humans and the weather.
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The European Union’s Emissions Trading System (EU ETS) is complemented by a Market Stability Reserve (MSR). After a major revision of the EU ETS in 2018, the MSR effectively makes the supply of allowances responsive to demand. In this paper, we show that a cap-and-trade scheme with an endogenous cap such as the EU ETS produces a Green Paradox. Abatement policies announced early but realized in the future are counter-effective because of the MSR: they increase cumulative emissions. We present the mechanisms in a two-period model, and then provide quantitative evidence of our result for an annual model disciplined on the price rise in the EU ETS that followed the introduction of the MSR. Our results point to the need for better coordination between different policies, such as the ‘European Green Deal’. We conclude with suggestions to improve the workings of an endogenous cap, ahead of the MSR review scheduled for 2021.
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Science journalism has never been more important, but citizens must sometimes struggle to find independent, evidence-based information. At the same time, conditions for specialist science journalists are becoming more difficult. This chapter discusses these conundrums and what they portend for the future of science journalism. It first tracks the evolution of the field, noting the long history of popular science and the presence of science stories in the mass media for as long as these channels have existed. The chapter then moves to reflections on characteristics of 21st-century science news content and opportunities and challenges confronting science journalists in this age of digital media and gig economy. © 2021 selection and editorial matter, Massimiano Bucchi and Brian Trench; individual chapters, the contributors.
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In our condition as human beings, we have experienced a love-and-hate relationship with technology since the very beginning: from primitive humans (probably scared the very first time they saw fire) to 19th century Luddites to the recent conspiracy theories that link 5G to COVID-19, human beings have dreaded technology. But, for bad or for good, machines—which could be loosely defined from an etymological point of view as “structures of any kind created by humans”—have been, are, and probably will be an essential part in the history of mankind, thus playing a fundamental in the social evolution of human. This chapter attempts to shed some light and provide some insights into plausible conjectures by exploring future developments, either in the short and medium or in the long term, which might result from a synergistic context where exponentially-increasing technological innovation may lead to a radical change, an evolutionary paradigm shift in human life and civilization, by reaching toward a post-technological era characterized by consciousness of the noosphere.
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Der Tagungsband widmet sich vielfältigen rechtlichen Herausforderungen und Ansätzen für eine umweltgerechte und nachhaltige Stadtentwicklung. Die Schwerpunkte liegen dabei auf dem Feld des kommunalen Klimaschutzes sowie auf dem Verkehrssektor. So geht es neben den Handlungsfeldern, Rechtsinstrumenten und Perspektiven der Anpassung um kommunale und regionale Wärmeplanung als neues Rechtsinstrument. Im Verkehrssektor werden sowohl der Rechtsrahmen für eine Verkehrswende in den Kommunen als auch die kommunalen Gestaltungsmöglichkeiten zur Förderung der E-Mobilität ausgelotet. Schließlich wird die Frage erörtert, wie die Kommunen den Flächenverbrauch reduzieren können, bevor sich der Tagungsband dem urbanen Wassermanagement und der wassersensiblen Stadtentwicklung widmet. Mit Beiträgen von Cathrin Zengerling; Juliane Albrecht; Christian Maaß; Roman Ringwald; Friederike Pfeifer, Felix Nowack; Jana Bovet und Moritz Reese.