although there are outstanding issues. First, the overwhelming majority of reviewers are from developed countries, although evidence suggests participation by developing country reviewers increased between the Fourth and Fifth Assessments. Second, earlier sections of chapters are more densely reviewed than later ones. This is true even when executive summaries are removed from analysis. In consequence, some sections on specialised topics may escape in-depth review. Thirdly, those review comments which are received make a valid and valuable contribution to the scientific development of chapters. We suggest how outstanding issues could be addressed, including through enhanced reviewer recognition, a wider role for review editors, adherence to mandated page lengths from early in the process, reviewer training, and consistency in reporting to allow systematic evaluation. Making such changes will result in more transparent, consistent and representative processes delivering reviews which effectively contribute to the credibility and legitimacy of future Global Environmental Assessments and, ultimately, their recognition and contribution.
Ambitious climate mitigation policies face social and political resistance. One reason is that existing policies insufficiently capture the diversity of relevant insights from the social sciences about potential policy outcomes. We argue that agent‐based models can serve as a powerful tool for integration of elements from different disciplines. Having such a common platform will enable a more complete assessment of climate policies, in terms of criteria like effectiveness, equity and public support. This article is categorized under: Climate Models and Modeling > Knowledge Generation with Models The Carbon Economy and Climate Mitigation > Policies, Instruments, Lifestyles, Behavior Policy and Governance > Multilevel and Transnational Climate Change Governance
The European Commission has proposed a carbon border adjustment mechanism (CBAM) that would apply the carbon price prevailing in the EU emissions trading system to import-related emissions. We conducted a survey to study perceptions of an EU CBAM among German key stakeholders from industry, civil society, and research in July 2021. We find that substantial support for CBAM exists as well as the expectation that the mechanism will eventually be introduced. We identified divergent views on key design options among stakeholder groups. Stakeholders from industry generally favour the continuation of free allocation of emissions allowances, rebates for exporters from the EU, coverage of only scope 1 emissions, and use of revenues for domestic spending. Stakeholders from civil society prefer phasing out free allocation, coverage only of imports, an emissions scope including all indirect emissions, exempting low-income countries and countries that do implement non-price-based climate policies, and the use of revenues to finance green transformation in low-income countries. Respondents from research would generally rather see free allocation being phased out, emissions coverage of scope 1 and 2, exemptions for low-income countries and countries that do implement non-price-based policies with comparable effects in relevant sectors and a transfer of revenues to support clean technologies in low-income countries and green technologies in the EU. Our survey design allows us to identify three cross-stakeholder group clusters, one containing stakeholders who are comparably more hesitant towards CBAM, a second one with respondents most in favour of introducing CBAM, as well as a “middle ground” cluster which contains views that are often in between the other two. We also compare the survey responses to the design of the Commission’s CBAM proposal to identify the most likely points of political disagreement.
To prevent the rapid spreading of the COVID-19 pandemic, the Egyptian government had imposed partial lockdown restrictions which led emissions reduction. This served as ideal conditions for a natural experiment, for study the effect of partial lockdown on the atmospheric aerosol chemistry and the enhanced secondary inorganic aerosol production in a semi-desert climate area like Egypt. To achieve this objective, SO2, NO2, and PM2.5 and their chemical compositions were measured during the pre-COVID, COVID partial lockdown, and post-COVID periods in 2020 in a suburb of Greater Cairo, Egypt. Our results show that the SO2, NO2, PM2.5 and anthropogenic elements concentrations follow the pattern pre-COVID > post-COVID > COVID partial lockdown. SO2 and NO2 reductions were high compared with their secondary products during the COVID partial lockdown compared with pre-COVID. Although, PM2.5, anthropogenic elements, NO2, SO2, SO4²⁻, NO3⁻, and NH4⁺ decreased by 39%, 38–55%, 38%, 32.9%. 9%, 14%, and 4.3%, respectively, during the COVID partial lockdown compared with pre-COVID, with the secondary inorganic ions (SO4²⁻, NO3⁻, and NH4⁺) being the dominant components in PM2.5 during the COVID partial lockdown. Moreover, the enhancement of NO3⁻ and SO4²⁻ formation during the COVID partial lockdown was high compared with pre-COVID. SO4²⁻ and NO3⁻ formation enhancements were significantly positive correlated with PM2.5 concentration. Chemical forms of SO4²⁻ and NO3⁻ were identified in PM2.5 based on their NH4⁺/SO4²⁻ molar ratio and correlation between NH4⁺ and both NO3⁻ and SO4²⁻. The particles during the COVID partial lockdown were more acidic than those in pre-COVID.
As the climate warms, many areas of the world are experiencing more frequent and extreme weather events. Hurricanes carry some of the costliest short-term socioeconomic repercussions in economic losses and people displaced. There is, however, little quantitative evidence regarding medium- to long-term effects, nor factors moderating recovery. Here we show that areas affected by hurricanes of category 4 or 5 in the southern US between 2014 and 2020 generally do not demonstrate full recovery in the longer term. Utilizing Visible Infrared Imaging Radiometer Suite (VIIRS) nighttime light data as a proxy for economic activity and population density, we build a timeline of recovery via nighttime light radiance levels. We exploit the difference in the eligibility for aid from the Federal Emergency Management Agency (FEMA) to apply a quasi-experimental method to identify changes in nighttime light radiance attributable to hurricanes. We find that after three years, affected areas demonstrate a reduction in nighttime light radiance levels of between 2 and 14% compared to the pre-disaster period. Combining these results with machine learning techniques, we are able to investigate those factors that contribute to recovery. We find counties demonstrating smaller reductions in nighttime light radiance levels in the months following the hurricane are buoyed by the amount of FEMA aid received, but that this aid does not foster a longer term return to normal radiance levels. Investigating areas receiving FEMA aid at the household and individual level, we find age and employment more important than other demographic factors in determining hurricane recovery over time. These findings suggest that aid may be more important in motivating short-term recovery for public entities than for individuals but is not sufficient to guarantee complete recovery in the longer term.
City-level policies are increasingly recognized as key components of strategies to reduce transport greenhouse gas emissions. However, at a global scale, their total efficiencies, costs, and practical feasibility remain unclear. Here, we use a spatially-explicit urban economic model, systematically calibrated on 120 cities worldwide, to analyze the impact of four representative policies aiming at mitigating transportation GHG emissions, also accounting for their economic welfare impacts and health co-benefits. Applying these policies in all cities, we find that total transportation GHG emissions can be reduced by 28% in 15 years, compared with the baseline scenario. However, the consequences of the same policies vary widely between cities, with specific effects depending on the policy considered, income level, population growth rate, spatial organization, and existing public transport supply. Impacts on transport emissions span from high to almost zero, and consequences in terms of welfare can either be positive or negative. Applying only welfare-increasing policies captures most of the emission reductions: overall, they reduce emissions by 20% in 15 years. Our results highlight that there is no one-size-fits-all optimal policy to mitigate urban transport emissions but that cities can match their specific situation with a selection of mitigation policies: hence, we call for global climate mitigation models to better represent heterogeneity across cities.
Phasing out coal is a prerequisite to achieving the Paris climate mitigation targets. In 2018, the German government established a multi-stakeholder commission with the mandate to negotiate a plan for the national coal phase-out, fueling a continued public debate over the future of coal. This study analyzes the German coal debate on Twitter before, during, and after the session of the so-called Coal Commission, over a period of three years. In particular, we investigate whether and how the work of the commission translated into shared perceptions and sentiments in the public debate on Twitter. We find that the sentiment of the German coal debate on Twitter becomes increasingly negative over time. In addition, the sentiment becomes more polarized over time due to an increase in the use of more negative and positive language. The analysis of retweet networks shows no increase in interactions between communities over time. These findings suggest that the Coal Commission did not further consensus in the coal debate on Twitter. While the debate on social media only represents a section of the national debate, it provides insights for policy-makers to evaluate the interaction of multi-stakeholder commissions and public debates.
Introducing a price floor in emissions trading schemes (ETS) theoretically stabilizes expectations on future carbon prices and thus fosters low-carbon investment. Yet, ex post evidence on high carbon prices is scant and the relevance of carbon pricing for investment decisions is frequently contested. We provide empirical ex ante evidence on how a price floor in the EU ETS would impact the size and portfolio of energy firms’ investments. Analyzing survey responses of high-level managers in 113 German energy and industry companies, we find that the level of the price floor is crucial. A low price floor trajectory only provides insurance against downward price fluctuations and would leave investments largely unchanged except for industries receiving electricity price compensation, which reduce their investments. A high floor, significantly increasing the price level beyond current expectations, leads to higher investment by the majority of firms, especially by green firms, while investment in fossil energy would partially be abolished. Our studies implies that price floors can be important design components of ETS. However, policymakers need to ensure that they are at sufficiently high levels to affect investment decisions in a meaningful way.
The ambitious climate targets set by industrialized nations worldwide cannot be met without decarbonizing the building stock. Using Germany as a case study, this paper takes stock of the extensive set of energy efficiency policies that are already in place and clarifies that they have been designed “in good faith” but lack in overall effectiveness as well as cost-efficiency in achieving these climate targets. We map out the market failures and behavioural considerations that are potential reasons for why realized energy savings fall below expectations and why the household adoption of energy-efficient and low-carbon technologies has remained low. We highlight the pressing need for data and modern empirical research to develop targeted and cost-effective policies seeking to correct these market failures. To this end, we identify some key research questions and identify gaps in the data required for evidence-based policy.
Municipalities are increasingly acknowledging the importance of urban form interventions that can reduce intra-city car travel in achieving more sustainable cities. Current academic knowledge for supporting such policies falls short in providing the spatial details required to plan specific interventions. Here, we develop an explainable machine learning framework to identify location-specific relevance of built environment for urban motorised travel, using a sample of 3.5 million car commutes over one year in Berlin and high-resolution urban form data. Results demonstrate that subcenters play a vital role in reducing commuting-related travel distance, giving support to the 15-minute city hypothesis. Observed threshold effects of induced CO2 emissions require low-carbon-policies targeted towards densifying the inner city while releasing peripheral low income communities from car dependence. This research provides a starting point for increasingly rich big data analyses of urban form for creating low-carbon and inclusive urban planning strategies.
Zusammenfassung Steuern und Abgaben auf Produkte oder Verbrauch mit gesellschaftlichen Folgekosten (externe Kosten) – sogenannte Pigou- oder Lenkungssteuern – sind ein gesellschaftliches „Win-Win-Instrument“. Sie verbessern die Wohlfahrt und schützen gleichzeitig die Umwelt und das Klima. Dies wird erreicht, indem umweltschädigende Aktivitäten einen Preis bekommen, der möglichst exakt der Höhe des Schadens entspricht. Eine konsequente Bepreisung der externen Kosten nach diesem Prinzip könnte in Deutschland erhebliche zusätzliche Einnahmen erbringen: Basierend auf bisherigen Studien zu externen Kosten wären zusätzliche Einnahmen in der Größenordnung von 348 bis 564 Milliarden Euro pro Jahr (44 bis 71 Prozent der gesamten Steuereinnahmen) möglich. Die Autoren warnen allerdings, dass die Bezifferung der externen Kosten mit erheblichen Unsicherheiten verbunden ist. Damit Lenkungssteuern und -abgaben ihre positiven Lenkungs- und Wohlstandseffekte voll entfalten können, seien zudem institutionelle Reformen notwendig.
Aligning development and climate goals means Africa’s energy systems will be based on clean energy technologies in the long term, but pathways to get there are uncertain and variable across countries. Although current debates about natural gas and renewables in Africa are heated, they largely ignore the substantial context specificity of the starting points, development objectives and uncertainties of each African country’s energy system trajectory. Here we—an interdisciplinary and majority African group of authors—highlight that each country faces a distinct solution space and set of uncertainties for using renewables or fossil fuels to meet its development objectives. For example, Ethiopia is headed for an accelerated green-growth pathway, but Mozambique is at a crossroads of natural gas expansion with implicit large-scale technological, economic, financial and social risks and uncertainties. We provide geopolitical, policy, finance and research recommendations to create firm country-specific evidence to identify adequate energy system pathways for development and to enable their implementation. Discussions abound regarding the future of African energy systems, yet they typically overlook the different starting points and development objectives of each country. This Perspective highlights these differences and calls for more context-specific attention to define low-carbon energy pathways.
The 2022 report of the Lancet Countdown is published as the world confronts profound and concurrent systemic shocks. Countries and health systems continue to contend with the health, social, and economic impacts of the COVID-19 pandemic, while Russia's invasion of Ukraine and a persistent fossil fuel overdependence has pushed the world into global energy and cost-of-living crises. As these crises unfold, climate change escalates unabated. Its worsening impacts are increasingly affecting the foundations of human health and wellbeing, exacerbating the vulnerability of the world's populations to concurrent health threats.
In the past few decades, major public health advances have happened in Europe, with drastic decreases in premature mortality and a life expectancy increase of almost 9 years since 1980. European countries have some of the best health-care systems in the world. However, Europe is challenged with unprecedented and overlapping crises that are detrimental to human health and livelihoods and threaten adaptive capacity, including the COVID-19 pandemic, the Russian invasion of Ukraine, the fastest-growing migrant crisis since World War 2, population displacement, environmental degradation, and deepening inequalities. Compared with pre-industrial times, the mean average European surface air temperature increase has been almost 1°C higher than the average global temperature increase, and 2022 was the hottest European summer on record. As the world's third largest economy and a major contributor to global cumulative greenhouse gas emissions, Europe is a key stakeholder in the world's response to climate change and has a global responsibility and opportunity to lead the transition to becoming a low-carbon economy and a healthier, more resilient society.
A health-friendly, climate resilient, and carbon-neutral pathway would deliver major benefits to people's health and wellbeing in China, especially for older populations, while simultaneously promoting high-quality development in the long run. This report is the third China Lancet Countdown report, led by the Lancet Countdown Regional Centre based in Tsinghua University. With the contributions of 73 experts from 23 leading institutions, both within China and globally, this report tracks progress through 27 indicators in the following five domains: (1) climate change impacts, exposure, and vulnerability; (2) adaptation, planning, and resilience for health; (3) mitigation actions and health co-benefits; (4) economics and finance; and (5) public and political engagement. From 2021 to 2022, two new indicators have been added, and methods have been improved for many indicators. Specifically, one of the new indicators measures how heat affects the hours that are safe for outdoor exercise, an indicator of particular relevance given the boom in national sports triggered by the summer and winter Olympics. Findings in this report, which coincide with the UN Framework Convention on Climate Change 27th Conference of the Parties (COP27) hosted in Egypt (where much attention is being focused on adaptation for clinically vulnerable populations), expose the urgency for accelerated adaptation and mitigation efforts to minimise the health impacts of the increasing climate change hazards in China.
Wildfires have increased in the last years and, when caused by intentional illegal burnings, are frequently run out of control. Wildfire has been pointed out as an important source of polycyclic aromatic hydrocarbons (PAHs) and trace elements (TEs) — such as, As, Ni, and Pb — to environmental compartments, and thus may pose a risk to human health and to the ecosystem. In 2020, the Brazilian biome, Pantanal, faced the largest losses by wildfires in the last 22 years. Ashes from the topsoil layer in Pantanal were collected after these wildfires at 20 sites divided into the sediment, forest, PF, PS, and degraded sites. Toxicity and associated risks for human health were also evaluated. The areas highly impacted by wildfires and by artisanal gold mining activities showed higher concentrations for TEs and PAHs than the protected areas. Pb varied from 8 ± 4 to 224 ± 81 mg kg⁻¹, and total PAH concentration ranged between 880 ± 314 and 1350 ± 70 ng g⁻¹, at sites impacted by anthropogenic activities. Moreover, health risk assessments for TE and PAH indicated a potentially great risk for children and adults, via ingestion, inhalation, and dermal pathway. The carcinogenic risks exceeded reference values, for both TE and PAH, suggesting harmful conditions, especially for vulnerable groups, such as children and the elderly. Graphical abstract
Climate change is an ongoing topic in nearly all areas of society since many years. A discussion of climate change without referring to scientific results is not imaginable. This is especially the case for policies since action on the macro scale is required to avoid costly consequences for society. In this study, we deal with the question of how research on climate change and policy are connected. In 2019, the new Overton database of policy documents was released including links to research papers that are cited by policy documents. The use of results and recommendations from research on climate change might be reflected in citations of scientific papers in policy documents. Although we suspect a lot of uncertainty related to the coverage of policy documents in Overton, there seems to be an impact of international climate policy cycles on policy document publication. We observe local peaks in climate policy documents around major decisions in international climate diplomacy. Our results point out that IGOs and think tanks-with a focus on climate change-have published more climate change policy documents than expected. We found that climate change papers that are cited in climate change policy documents received significantly more citations on average than climate change papers that are not cited in these documents. Both areas of society (science and policy) focus on similar climate change research fields: biology, earth sciences, engineering, and disease sciences. Based on these and other empirical results in this study, we propose a simple model of policy impact considering a chain of different document types: The chain starts with scientific assessment reports (systematic reviews) that lead via science communication documents (policy briefs, policy reports or plain language summaries) and government reports to legislative documents.
Demand-side behavioural change interventions promote a reduction in car use, and shift to low carbon transport modes, thereby addressing economic, health and GHG emissions-related costs associated with car-dependent lifestyles. However, the relative effectiveness of such interventions in initiating transport behaviour change has not been evaluated systematically. Here, we conduct a systematic review and meta-analysis to evaluate the evidence on behavioural interventions in changing transport-related behavioural patterns. Relying on 37 literature reviews and 41 additional new studies, we identify more than 450 cases of behavioural interventions. Our analysis reveals that behavioural measures are effective in increasing the percentage growth of public transit and active transport mode use as well as decreasing car use at the personal level. However, their effectiveness in shifting commuters away from cars to more sustainable modes of transport at the aggregate level is limited. Our findings suggest that behavioural interventions have a role to play in reducing the health, economic and environmental costs of car-centric transportation systems. We find that, under the best-case scenario, behavioural interventions can contribute up to a 5% per cent reduction of global GHG emissions from urban transport, or about 150Mt CO 2 /yr, a notable but limited potential compared to the reductions necessary to meet sectoral goals. Critical analysis of studies in our review indicates that interdisciplinary researchers interested in these issues should take a more strategic and rigorous approach—better study designs, more representative samples, and consideration of infrastructure effects—to determine which interventions are most effective in tackling multi-faceted urban transport issues.
Scholars disagree about the plausibility of preference purification. Some see it as a familiar phenomenon. Others denounce it as conceptually incoherent, postulating that it relies on the psychologically implausible assumption of an inner rational agent. I argue that different notions of rationality can be leveraged to advance the debate: procedural rationality and structural rationality. I explicate how structural rationality, in contrast to procedural rationality, allows us to offer an account of the guiding idea behind preference purification that avoids inner rational agents. Afterward, I address two pressing challenges against preference purification that emerge under the structural rationality account.
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