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- ItemSocial tipping dynamics for stabilizing Earth's climate by 2050(2020) Otto, Ilona M.; Donges, Jonathan F.; Cremades, Roger; Bhowmik, Avit; Hewitt, Richard J.; Lucht, Wolfgang; Rockström, Johan; Allerberger, Franziska; McCaffrey, Mark; Doe, Sylvanus S.P.; Lenferna, Alex; Morán, Nerea; van Vuuren, Detlef P.; Schellnhuber, Hans JoachimSafely achieving the goals of the Paris Climate Agreement requires a worldwide transformation to carbon-neutral societies within the next 30 y. Accelerated technological progress and policy implementations are required to deliver emissions reductions at rates sufficiently fast to avoid crossing dangerous tipping points in the Earth's climate system. Here, we discuss and evaluate the potential of social tipping interventions (STIs) that can activate contagious processes of rapidly spreading technologies, behaviors, social norms, and structural reorganization within their functional domains that we refer to as social tipping elements (STEs). STEs are subdomains of the planetary socioeconomic system where the required disruptive change may take place and lead to a sufficiently fast reduction in anthropogenic greenhouse gas emissions. The results are based on online expert elicitation, a subsequent expert workshop, and a literature review. The STIs that could trigger the tipping of STE subsystems include 1) removing fossil-fuel subsidies and incentivizing decentralized energy generation (STE1, energy production and storage systems), 2) building carbon-neutral cities (STE2, human settlements), 3) divesting from assets linked to fossil fuels (STE3, financial markets), 4) revealing the moral implications of fossil fuels (STE4, norms and value systems), 5) strengthening climate education and engagement (STE5, education system), and 6) disclosing information on greenhouse gas emissions (STE6, information feedbacks). Our research reveals important areas of focus for larger-scale empirical and modeling efforts to better understand the potentials of harnessing social tipping dynamics for climate change mitigation.
- ItemExtending Near-Term Emissions Scenarios to Assess Warming Implications of Paris Agreement NDCs(Chichester : John Wiley and Sons Inc, 2018) Gütschow, J.; Jeffery, M.L.; Schaeffer, M.; Hare, B.In the Paris Agreement countries have agreed to act together to hold global warming well below 2°C over preindustrial levels and to pursue efforts to limit warming to 1.5°C. To assess if the world is on track to meet this long-term temperature goal, countries' pledged emissions reductions (Nationally Determined Contributions, NDCs) need to be analyzed for their implied warming. Several research groups and nongovernmental organizations have estimated this warming and arrived at very different results but have invariably concluded that the current pledges are inadequate to hold warming below 2°C, let alone 1.5°C. In this paper we analyze different methods to estimate 2100 global mean temperature rise implied by countries' NDCs, which often only specify commitments until 2030. We present different methods to extend near-term emissions pathways that have been developed by the authors or used by different research groups and nongovernmental organizations to estimate 21st century warming consequences of Paris Agreement commitments. The abilities of these methods to project both low and high warming scenarios in line with the scenario literature is assessed. We find that the simpler methods are not suitable for temperature projections while more complex methods can produce results consistent with the energy and economic scenario literature. We further find that some methods can have a strong high or low temperature bias depending on parameter choices. The choice of methods to evaluate the consistency of aggregated NDC commitments is very important for reviewing progress toward the Paris Agreement's long-term temperature goal.
- ItemGrounding Social Foundations for Integrated Assessment Models of Climate Change(Hoboken, NJ : Wiley-Blackwell, 2020) Mathias, Jean‐Denis; Debeljak, Marko; Deffuant, Guillaume; Diemer, Arnaud; Dierickx, Florian; Donges, Jonathan F.; Gladkykh, Ganna; Heitzig, Jobst; Holtz, Georg; Obergassel, Wolfgang; Pellaud, Francine; Sánchez, Angel; Trajanov, Aneta; Videira, NunoIntegrated assessment models (IAMs) are commonly used by decision makers in order to derive climate policies. IAMs are currently based on climate-economics interactions, whereas the role of social system has been highlighted to be of prime importance on the implementation of climate policies. Beyond existing IAMs, we argue that it is therefore urgent to increase efforts in the integration of social processes within IAMs. For achieving such a challenge, we present some promising avenues of research based on the social branches of economics. We finally present the potential implications yielded by such social IAMs. ©2020. The Authors. Earth's Future published by Wiley Periodicals LLC on behalf of American Geophysical Union
- ItemBetween Scylla and Charybdis: Delayed mitigation narrows the passage between large-scale CDR and high costs(Bristol : IOP Publishing, 2018) Strefler, Jessica; Bauer, Nico; Kriegler, Elmar; Popp, Alexander; Giannousakis, Anastasis; Edenhofer, OttmarThere are major concerns about the sustainability of large-scale deployment of carbon dioxide removal (CDR) technologies. It is therefore an urgent question to what extent CDR will be needed to implement the long term ambition of the Paris Agreement. Here we show that ambitious near term mitigation significantly decreases CDR requirements to keep the Paris climate targets within reach. Following the nationally determined contributions (NDCs) until 2030 makes 2 °C unachievable without CDR. Reducing 2030 emissions by 20% below NDC levels alleviates the trade-off between high transitional challenges and high CDR deployment. Nevertheless, transitional challenges increase significantly if CDR is constrained to less than 5 Gt CO2 a−1 in any year. At least 8 Gt CO2 a−1 CDR are necessary in the long term to achieve 1.5 °C and more than 15 Gt CO2 a−1 to keep transitional challenges in bounds.
- ItemThe world’s biggest gamble(Hoboken, NJ : Wiley, 2016) Rockström, Johan; Schellnhuber, Hans Joachim; Hoskins, Brian; Ramanathan, Veerabhadran; Schlosser, Peter; Brasseur, Guy Pierre; Gaffney, Owen; Nobre, Carlos; Meinshausen, Malte; Rogelj, Joeri; Lucht, WolfgangThe scale of the decarbonisation challenge to meet the Paris Agreement is underplayed in the public arena. It will require precipitous emissions reductions within 40 years and a new carbon sink on the scale of the ocean sink. Even then, the world is extremely likely to overshoot. A catastrophic failure of policy, for example, waiting another decade for transformative policy and full commitments to fossil‐free economies, will have irreversible and deleterious repercussions for humanity's remaining time on Earth. Only a global zero carbon roadmap will put the world on a course to phase‐out greenhouse gas emissions and create the essential carbon sinks for Earth‐system stability, without which, world prosperity is not possible.
- ItemFuture Hydroclimatic Impacts on Africa: Beyond the Paris Agreement(Hoboken, NJ : Wiley-Blackwell, 2019) Piemontese, Luigi; Fetzer, Ingo; Rockström, Johan; Jaramillo, FernandoProjections of global warming in Africa are generally associated with increasing aridity and decreasing water availability. However, most freshwater assessments focus on single hydroclimatic indicators (e.g., runoff, precipitation, or aridity), lacking analysis on combined changes in evaporative demand, and water availability on land. There remains a high degree of uncertainty over water implications at the basin scale, in particular for the most water-consuming sector—food production. Using the Budyko framework, we perform an assessment of future hydroclimatic change for the 50 largest African basins, finding a consistent pattern of change in four distinct regions across the two main emission scenarios corresponding to the Paris Agreement, and the business as usual. Although the Paris Agreement is likely to lead to less intense changes when compared to the business as usual, both scenarios show the same pattern of hydroclimatic shifts, suggesting a potential roadmap for hydroclimatic adaptation. We discuss the social-ecological implications of the projected hydroclimatic shifts in the four regions and argue that climate policies need to be complemented by soil and water conservation practices to make the best use of future water resources. ©2019. The Authors.
- ItemMeasuring Success: Improving Assessments of Aggregate Greenhouse Gas Emissions Reduction Goals(Chichester : John Wiley and Sons Inc, 2018) Jeffery, M.L.; Gütschow, J.; Rocha, M.R.; Gieseke, R.Long-term success of the Paris Agreement will depend on the effectiveness of the instruments that it sets in place. Key among these are the nationally determined contributions (NDCs), which elaborate country-specific goals for mitigating and adapting to climate change. One role of the academic community and civil society in supporting the Paris Agreement is to assess the consistency between the near-term action under NDCs and the agreement's long-term goals, thereby providing insight into the chances of long-term success. Here we assess the strengths and weaknesses of current methods to estimate the effectiveness of the mitigation component of NDCs and identify the scientific and political advances that could be made to improve confidence in evaluating NDCs against the long-term goals. Specifically, we highlight (1) the influence of post-2030 assumptions on estimated 21st century warming, (2) uncertainties arising from the lack of published integrated assessment modeling scenarios with long-term, moderate effort reflecting a continuation of the current political situation, and (3) challenges in using a carbon budget approach. We further identify aspects that can be improved in the coming years: clearer communication regarding the meaning, likelihood, and timeframe of NDC consistent warming estimates; additional modeling of long-term, moderate action scenarios; and the identification of metrics for assessing progress that are not based solely on emissions, such as infrastructure investment, energy demand, or installed power capacity.