Publications

Concerns have been raised that payments for ecosystem services (PES) may crowd out land users' non-monetary motivations to engage in conservation behavior. Especially once incentives are terminated, PES risk to be ineffective or even counterproductive. So far, research has produced mixed evidence. We present the first meta-analysis of studies that investigated crowding effects of PES through lab-in-the-field experiments with 2,894 real-world resource users taking 44,540 conservation decisions. On average, PES are successful in increasing conservation behavior and do not crowd out conservation behavior once incentives have been terminated. Although PES demonstrate greater effectiveness in settings where local resource users directly benefit compared to settings where third parties benefit, there is no evidence suggesting systematic differences in crowding effects between these two situations once PES have been terminated. Based on the available experimental evidence, the frequently voiced risk that PES crowd-out conservation, especially once payments are terminated, cannot be substantiated. However, methodological concerns regarding the internal and external validity of current experiments raise questions about the broader applicability of these findings. This paper outlines potential avenues for future research to address these challenges.

Economic games have emerged as promising tools for fostering sustainable resource management, yet their gender dynamics remain underexplored. We examine how women's participation relates to the effectiveness of game-based learning in 56 Indian communities facing water management challenges. These structured experiential learning environments allow participants to develop system understanding, problem-solving capacities, and collective action through active engagement. Our results suggest that greater female involvement is associated with improved water management outcomes two years after the intervention. Notably, the presence of female leaders correlated with broader participation among women, which in turn was linked to the development of more effective management rules. These findings indicate that gender-balanced participation may enhance the success of such interventions. Incorporating women in game-based learning has the potential to support long-term improvements in resource management, highlighting the importance of inclusive approaches.

Relational values emphasize the desirable characteristics of nature–society relationships. Unlike instrumental values, relational values have not yet been subjected to monetary quantification, although they may be relevant to environmental policymaking or climate change adaptation decisions which often rely on cost–benefit approximations. This paper explores the quantification of relational values within a contingent valuation scenario both in monetary (one-time donation) and non-monetary terms (Likert-scale, ranking) as well as using a measure that elicits the desired allocation of government budget for adaptation. We conduct two surveys within the context of adaptation projects, aiming to protect the traditional lifestyles of atoll islanders on the Solomon Islands and coastal communities in Bangladesh. In these surveys, we employ two valuation scenarios – one with explicit mention of relational value losses, and one without. Information on relational losses led to no increases in monetary or non-monetary valuation but to a slightly higher allocation of government budget in Bangladesh. We further assess and discuss the validity of our measures, also accounting for respondents' financial situation. Our findings suggest that emphasizing relational losses could significantly increase disaster management funding in Bangladesh, with a potential 55% budget increase based on our treatment effect. We further discuss the difficulties in quantifying relational values in a context with limited ability to pay and the importance of considering deliberative approaches for ensuring that all dimensions of human-nature relationships are adequately considered in adaptation policy decision-making.

Does competition affect moral behavior? This fundamental question has been debated among leading scholars for centuries, and more recently, it has been tested in experimental studies yielding a body of rather inconclusive empirical evidence. A potential source of ambivalent empirical results on the same hypothesis is design heterogeneity—variation in true effect sizes across various reasonable experimental research protocols. To provide further evidence on whether competition affects moral behavior and to examine whether the generalizability of a single experimental study is jeopardized by design heterogeneity, we invited independent research teams to contribute experimental designs to a crowd-sourced project. In a large-scale online data collection, 18,123 experimental participants were randomly allocated to 45 randomly selected experimental designs out of 95 submitted designs. We find a small adverse effect of competition on moral behavior in a meta-analysis of the pooled data. The crowd-sourced design of our study allows for a clean identification and estimation of the variation in effect sizes above and beyond what could be expected due to sampling variance. We find substantial design heterogeneity—estimated to be about 1.6 times as large as the average standard error of effect size estimates of the 45 research designs—indicating that the informativeness and generalizability of results based on a single experimental design are limited. Drawing strong conclusions about the underlying hypotheses in the presence of substantive design heterogeneity requires moving toward much larger data collections on various experimental designs testing the same hypothesis.

Rising sea levels are projected to affect millions of coastal inhabitants, as climate change is threatening livelihoods all over the world. Those in charge of policy in affected areas will have to weigh the costs and benefits of moving people and communities out of harm's way (retreat) versus accommodating and protecting them in situ (resist). Decision-making solely based on direct material benefits of a location neglects other value types that are crucial to accurately reflect the actual valuation of the land. Relational values arise from the human-nature relationship and have recently been recognized as an important source of valuation for land beyond material benefits. However, since relational values are difficult to determine, incorporating them in the decision-making presents a challenge. Our contention is that the implementation of deliberative and inclusive approaches, such as citizens' assemblies, can serve as an effective means of developing adaptation policies that incorporate relational values.

This paper presents novel evidence of no crowding out, of either motivations or donations, among those terminated from an ongoing program of payments for ecosystem services (PES) in Colombia. PES programs have risen in number. However, claims about perverse impacts after programs end could inhibit their growth. PES end for different reasons (planned duration, budget reduction, issues in implementation) and in different ways (some participants or all). An expressed concern for PES is that receiving payments lowers conservation, after PES end, if participants' intrinsic motivations for conservation are 'crowded out' by financial incentives. We test for crowding out by an ongoing program in which some but not all contracts were terminated. We see no evidence of crowding out, since neither the motivations nor the donations for the terminated farmers are significantly different than for non-PES land owners (and this is robust to matching on levels of assets, residence on farm past donation behavior, main economic activity, and participation in collective activities). Our results add evidence from an actual PES to literature questioning the relevance, importance and even sign of crowding effects.

Climate hazards destroy the livelihoods and assets of millions of people worldwide, but also spur solidarity within affected communities. We conducted a pre-registered incentivized online experiment with a sample of 769 UK residents to understand better solidarity behavior framed in the context of flooding. In the experiment, participants make costly adaptation decisions that reduce their own risk of endowment loss. Moreover, they can make solidarity transfers to affected partners if unaffected themselves. Participants are matched with a partner who takes adaptation decisions, too. We experimentally vary the adaptation costs of the partner to be either the same (control condition) or heterogenous (known or uncertain). In the control condition, participants show less solidarity with non-adapted partners than with adapted ones. On average, the heterogenous adaptation cost treatments do not significantly affect observed solidarity transfers. Explorative analyses indicate, however, that differences in transfers to adapted and non-adapted partners are mediated by one's adaptation behavior. Under known heterogenous adaptation costs, risk-averse players (who adapted themselves) show as much solidarity with adapted as with non-adapted partners. Overall, the results suggest that information about adaptation cost heterogeneity may promote solidarity after exogenous shocks when people cannot easily adapt proactively.

We study how economic, conflict, and environmental drivers of migration influence immigration acceptance in a receiving country. We carried out an online survey experiment in autumn 2015 with 686 student participants from the University of Innsbruck in Austria. In the survey experiment, respondents state their acceptance for a fictitious migrant from Chad where we vary the following causes of the migration decision: (1) violent conflicts, (2) environmental degradation due to global climate change, (3) environmental degradation due to local overuse, and (4) better economic prospects. We find that respondents support migrants who move because of climate change as much as conflict migrants. Acceptance is lowest for migrants who decide to leave for economic reasons, while it is slightly higher in the case of environmental degradation due to local overuse. Strikingly, a sizable share of respondents (25%) would even reject conflict migrants. Respondents who perceive a negative correlation between welfare, crime rates and job opportunities, and the presence of immigrants display lower immigration acceptance for all motives underlying the migration decision. In addition, we find heterogeneous effects depending on the respondents' gender and political affiliation. Respondents with right-wing party preferences disclose lower acceptance levels for all causes except conflict. Female respondents are more accepting of climate migrants and less of economic migrants than men. This paper informs the debate around the ongoing political and societal polarization in Europe and elsewhere on the acceptance of different types of migrants.

__Background:__ Many countries, such as Germany, struggle tovaccinate enough people against COVID-19 despite the availability ofsafe and efficient vaccines. With new variants emerging and the need for booster vaccinations, overcoming vaccination hesitancy gains importance. The research todate has revealed some promising, albeit contentious, interventionstoincrease vaccination intention. However, these have yet tobe tested for their effectiveness inincreasing vaccination rates. __Methods&results:__ We conducted apreregistered survey experiment with N=1,324 participants inGermany in May/June 2021. This was followed by aseries ofemails reminding participants toget vaccinated inAugust and concluded with afollow-up survey inSeptember. We experimentally assess whether debunking vaccination myths, highlighting the benefits ofbeing vaccinated, orsending vaccination reminders decreases hesitancy. Inthe survey experiment, we find no increase inthe intention tovaccinate regardless ofthe information provided. However, communicating vaccination benefits over several weeks reduced the likelihood ofnot being vaccinated by 9percentage points, which translates into a 27% reduction compared tothe control group. Debunking vaccination myths and reminders alone also decreased the likelihood, yet not significantly. __Discussion:__ Our findings suggest that ifsoft governmental interventions such as information campaigns are employed, highlighting benefits should be given preference over debunking vaccination myths. Furthermore, itseems that repeated messages affect vaccination action while onetime messages might be insufficient, even for increasing vaccination intentions. Our study highlights the importance oftesting interventions outside ofsurvey experiments that are limited tomeasuring vaccination intentions—not actions—and immediate changes inattitudes and intentions—not long-term changes.

People's willingness to engage in prosocial behavior can affect how vulnerable and resilient populations are to climate hazards. We study how different types of climate hazards, fast-onsetting cyclones and slowly rising sea-levels, might affect peoples' prosociality using incentivized behavioral tasks. We sample people who are at the forefront of climate change and either experienced Typhoon Haiyan in the Philippines (study 1; n=378) or are from sea-level rise hotspots (study 2; n=1047) in Solomon Islands, Bangladesh, and Vietnam. We experimentally manipulate the salience of these hazards through recall or informational videos. Results from study 1 show that increases in prosociality are (i) independent of whether supportive behaviors or conflicts are recalled, (ii) are not only targeted to a narrow in-group, and (iii) do not come with increases in antisocial behaviors. In study 2, we also find that people behave more prosocial when they are informed about the impacts of rising sea-levels. Our survey evidence suggests that people who already perceive the threat of displacement due to rising sea-levels are also more prosocial. Overall, peoples' responses to both types of hazards are geared towards collective action, which could strengthen their adaptive capacity to deal with climate risks.

Climate change is projected to increase the number of extreme weather events, which may lead to cascading impacts, feedbacks, and tipping points not only in the biophysical system but also in the social system. To better understand societal resilience in risky environments, we analyzed people's attachment to place, their willingness to take risks, and how these change in response to extreme weather events. We conducted a survey with 624 respondents at the forefront of climate change in Asia: the river deltas in Bangladesh and Vietnam. Our findings confirm that most people prefer staying. Yet crucially, we find that (i) self-reported experiences of climate-related hazards are associated with increased risk aversion and place attachment, reinforcing people's preferences to stay in hazardous environments; (ii) people with experiences of hazards are more likely aspiring to move to high-income destinations, arguably being beyond the reach of their capacities; and (iii) changes in aspirations to move abroad are connected to the changes in risk aversion and place attachment. The fact that preferences are associated with cumulative experiences of hazards and interact with aspirations to move to high-income destinations may contribute to our understanding of why so many people stay in hazardous environments.

Decentralization of water management in Namibia follows a community-based co-management approach, emphasizing the inclusion of women in local leadership. Building on a random sample of 32 water point chairpersons, 17 female and 15 male, and 384 villagers in rural northern Namibia, we document that women are equally represented as chairpersons and that they are significantly more educated and younger than their male counterparts. However, most of the female leaders come from the family of the traditional leader. We then show that opinions about the role of a leader (such as the belief that 'men make better leaders' or 'it is sometimes acceptable to take a bribe') do not differ between male and female leaders. However, their opinions differ significantly from those of the average villager. Thus, our assessment reveals that although men and women are equally represented in numbers, it has not necessarily led to the adoption of new ideas about and conceptions of leadership and gender roles in practice so far. We discuss how some aspects of the democratic blueprint are accepted while others are rejected, adapted, or transformed to fit local specificities.

This study tests the common conception that democratically elected leaders behave in the interest of their constituents more than traditional chiefs do. Our sample includes 64 village leaders and 384 villagers in rural Namibia, where democratically elected leaders and traditional chiefs coexist. We analyze two main attributes of local political leaders: procedural fairness preferences and preferential treatment of relatives (nepotism). We also measure personality traits and social preferences, and conduct standardized surveys on local governance practices and villagers' perceptions of their leaders' performance. Our results indicate that traditional chiefs are as likely to implement fair, democratic decision-making procedures, and are as unlikely to be nepotistic. Moreover, elected leaders and chiefs express similar social preferences and personality traits. These findings align with villagers' perceptions of most leaders in our sample as being popular and fair, and villagers' responses reveal a discrepancy between planned and de facto implementation of democratic institutions.

Time discounting – the degree to which individuals value current more than future resources – is an important component of natural resource conservation. As a response to climate change impacts in island communities, such as sea level rise, discounting the future can be a rational response due to increased stress on natural resources and uncertainty about whether future generations will have the same access to the same resources. By incorporating systematic responses of discount rates into models of resource conservation, realistic expectations of future human responses to climate change and associated resource stress may be developed. This paper illustrates the importance of time discounting through a theoretical agent-based model of resource use in island communities. A discount rate change can dramatically change projections about future migration and community-based conservation efforts. Our simulation results show that an increase in discount rates due to a credible information shock about future climate change impacts is likely to speed resource depletion. The negative impacts of climate change are therefore likely to be underestimated if changes in discount rates and emerging migration patterns are not taken into account.