Push, don't nudge: behavioral spillovers and policy instruments

Policy interventions are generally evaluated for their direct effectiveness. Little is known about their ability to persist over time and spill across contexts. These latter aspects can reinforce or offset the direct impacts depending on the policy instrument choice. Through an online experiment with 1,486 subjects, we compare four widely used policy instruments in terms of their ability to enforce a norm of fairness in the Dictator Game, and to persist over time (i.e., to a subsequent untreated Dictator Game) or spill over to a norm of cooperation (i.e., to a subsequent Prisoner's Dilemma). As specific policy interventions, we employed two instances of nudges: defaults and social information; and two instances of push measures: rebates and a minimum donation rule. Our results show that (i) rebates, the minimum donation rule and social information have a positive direct effect on fairness, although the effect of social information is only marginally significant, and that (ii) the effect of rebates and the minimum donation rule persists in the second game, but only within the same game type. These findings demonstrate that, within our specific design, push measures are more effective than nudges in promoting fairness

Solar geoengineering may lead to excessive cooling and high strategic uncertainty

Climate engineering-the deliberate large-scale manipulation of the Earth's climate system-is a set of technologies for reducing climate-change impacts and risks. It is controversial and raises novel governance challenges [T. C. Schelling, Climatic Change, 33, 303-307 (1996); J. Virgoe, Climatic Change, 95, 103-119 (2008)]. We focus on the strategic implications of solar geoengineering. When countries engineer the climate, conflict can arise because different countries might prefer different temperatures. This would result in too much geoengineering: the country with the highest preference for geoengineering cools the planet beyond what is socially optimal at the expense of the others-a theoretical possibility termed "free-driving" [M. L. Weitzman, Scand. J. Econ., 117, 1049-1068 (2015)]. This study is an empirical test of this hypothesis. We carry out an economic laboratory experiment based on a public "good or bad" game. We find compelling evidence of free-driving: global geoengineering exceeds the socially efficient level and leads to welfare losses. We also evaluate the possibility of counteracting the geoengineering efforts of others. Results show that countergeoengineering generates high payoff inequality as well as heavy welfare losses, resulting from both strategic and behavioral factors. Finally, we compare strategic behavior in bilateral and multilateral settings. We find that welfare deteriorates even more under multilateralism when countergeoengineering is a possibility. These results have general implications for governing global good or bad commons

Timing of Mitigation and Technology Availability in Achieving a Low-Carbon World

This paper analyzes the economic and investment implications of a series of climate mitigation scenarios, characterized by different levels of ambition for long-term stabilization goals and transitional pathways. Results indicate that although milder climate objectives can be achieved at moderate costs, stringent stabilization paths, compatible with the 2°C target, might require significant economic resources. Innovation and technology are shown to be able to mitigate, but not structurally alter, this trade-off. Technologies that allow capturing CO2 from the atmosphere are shown to be important for expanding the feasibility space of stringent climate policies, though only if deployed at a scale which would represent a tremendous challenge. In general, the analysis indicates that the timing of mitigation is an important factor of cost containment, with early action being desirable. It also elaborates on the set of mitigation strategies and policies that would be required to achieve climate protection at maximum efficiency

On the Use of Nudges to Affect Spillovers in Environmental Behaviors

Environmental self-identity is considered a promising lever to generate positive spillovers across pro-environmental behaviors: existing evidence shows that it is positively correlated with pro-environmental choices and that it can be easily manipulated, by reminding individuals of their past pro-environmental actions. However, it remains unclear whether it can be successfully used for environmental policy making. In two online, incentive-compatible experiments, we manipulate participants' environmental self-identity and test whether this leads to increased donations to an environmental charity. Additionally, we investigate the interaction between self-identity priming and two commonly used behavioral policy tools: social information (Study 1, N = 400) and goal commitment (Study 2, N = 495). Our results suggest caution in leveraging environmental self-identity to promote pro-environmental behaviors, provide indications on how to target policies based on self-identity primes, and offer novel evidence on the interaction between different behavioral policy tools

Limited emission reductions from fuel subsidy removal except in energy exporting regions

Hopes are high that removing fossil fuel subsidies could help to mitigate climate change by discouraging inefficient energy consumption and levelling the playing field for renewables1–3. In September 2016, the G20 countries re-affirmed their 2009 commitment (at the G20 Leaders’ Summit) to phase out fossil fuel subsidies4,5 and many national governments are using today’s low oil prices as an opportunity to do so6–9. In practical terms, this means abandoning policies that decrease the price of fossil fuels and electricity generated from fossil fuels to below normal market prices10,11. However, whether the removal of subsidies, even if implemented worldwide, would have a large impact on climate change mitigation has not been systematically explored. Here we show that fossil fuel subsidy removal would have a small impact on global energy demand and carbon dioxide emissions and would not increase renewable energy use by 2030. Subsidy removal would reduce the carbon price necessary to stabilize greenhouse gas concentration at 550 parts per million by only 2–12 per cent under low oil prices. Removing subsidies in most regions would deliver smaller emission reductions than the Paris Agreement (2015) climate pledges and in some regions global subsidy removal may actually lead to an increase in emissions, owing to either coal replacing subsidized oil and natural gas or natural-gas use shifting from subsidizing, energy-exporting regions to non-subsidizing, importing regions. Our results show that subsidy removal would result in the largest CO2 emission reductions in oil- and gas-exporting regions, where reductions would exceed their climate pledges and where subsidy removal would also affect fewer people below the poverty line than in lower-income regions

Bring digital twins back to Earth

We reflect on the development of digital twins of the Earth, which we associate with a reductionist view of nature as a machine. The projects of digital twins deviate from contemporary scientific paradigms in the treatment of complexity and uncertainty, and does not engage with critical and interpretative social sciences. We contest the utility of digital twins for addressing climate change issues and discuss societal risks associated with the concept, including the twins' potential to reinforce economicism and governance by numbers, emphasizing concerns about democratic accountability. We propose a more balanced alternative, advocating for independent institutions to develop diverse models, prioritize communication with simple heuristic‐based models, collect comprehensive data from various sources, including traditional knowledge, and shift focus away from physics‐centered variables to inform climate action. We argue that the advancement of digital twins should hinge on stringent controls, favoring a nuanced, interdisciplinary, and democratic approach that prioritizes societal well‐being over blind pursuit of computational sophistication. This article is categorized under: Climate Models and Modeling > Earth System Models Climate Models and Modeling > Knowledge Generation with Models Climate, History, Society, Culture > Disciplinary Perspective