Jan Freihardt

Last Name

Freihardt

First Name

Jan

ORCID

0000-0003-2096-0335

Organisational unit

03446 - Bernauer, Thomas / Bernauer, Thomas

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Publications 1 - 10 of 22

Assessing riverbank erosion in Bangladesh using time series of Sentinel-1 radar imagery in the Google Earth Engine
Freihardt, Jan; Frey, Othmar (2023)
Natural Hazards and Earth System Sciences
Riverbank erosion occurs along many of the Earth's river systems, affecting riverine populations by destroying agricultural land and housing. In this study, we detected past events of riverbank erosion along the Jamuna River in Bangladesh using time series of Sentinel-1 satellite radar imagery, ground-range-detected (GRD) data with a 12 d revisit cycle, available in the Google Earth Engine (GEE). Eroded land is detected by performing a land cover classification and by detecting land cover changes from vegetated areas before the monsoon to sand or water after the monsoon. Further, settlements are detected as persistent scatterers and classified as eroded if they are located on eroded land. We found that with Sentinel-1 data, erosion locations can be determined already 1 month after the end of the monsoon and hence potentially earlier than using optical satellite images which depend on cloud-free daylight conditions. Further, we developed an interactive GEE-based online tool allowing the user to explore where riverbank erosion has destroyed land and settlements along the Jamuna in five monsoon seasons (2015–2019). The source code of our implementation is publicly available, providing the opportunity to reproduce the results, to adapt the algorithm and to transfer our results to assess riverbank erosion in other geographical settings.
Trapped by climate change? (In)voluntary immobility in Bangladesh
Freihardt, Jan (2025)
Regional Environmental Change
While there has been a considerable conceptual discussion of trapped populations in the environmental migration literature, the empirical evidence on their existence is scarce. I examine why many people remain in environmentally vulnerable areas by analyzing newly collected survey panel data of 1515 household heads living along the Jamuna River in Bangladesh, an area affected by riverbank erosion and flooding. To examine whether immobility is voluntary or involuntary, I assess the migration aspirations and capability to move of those who did not migrate after environmental shocks occurred in their village. The majority (82%) of non-migrants can be classified as voluntary non-migrants, while 13% can be considered trapped and the remaining 5% as acquiescent non-migrants. Being affected by erosion significantly increases the likelihood that immobility is involuntary by 7.9 percentage points, while also lowering the socio-economic status of the affected population. Taken together, these results suggest that environmental change may indeed lead to the trapping of parts of the population in exposed areas by eroding their capability to move while simultaneously increasing their migration aspirations. The findings have important policy implications, as they raise a word of caution against prematurely labeling all populations staying in environmentally exposed areas as trapped without considering their migration aspirationsa majority may in fact be voluntary non-migrants.
Perceptions of environmental changes among a climate-vulnerable population from Bangladesh
Freihardt, Jan (2024)
Climatic Change
Effective climate change adaptation requires a thorough understanding of whether and how affected populations perceive climatic and environmental changes. Existing research has been inconclusive regarding the consistency of these perceptions compared to objective meteorological indicators. Moreover, no systematic comparison has been done for the perception of discrete environmental events such as floods or erosion. This study relies on novel panel survey data of approximately 1700 households residing along the Jamuna River in Bangladesh as well as on unique individual-level, satellite-based erosion data. It compares respondents' perceptions of environmental events, namely riverbank erosion, and three climate change indicators, specifically long-term temperature change and changes in precipitation during wet and dry seasons, to objective measurements using satellite imagery and climatic time-series data (CRU TS). I find that long-term temperature change is perceived more accurately than long-term changes in precipitation. Given that educational attainment and climate change literacy among the study population are low, this indicates that global temperature increases are felt even by remote populations who have never heard the term climate change. Erosion is strongly overestimated, especially by those respondents who had been personally affected by it. Since human behavior is guided by perceptions rather than objective data, this has important policy implications, underlining the importance of considering people's perceptions if the goal is to assist them in adapting to environmental changes.
Choosing to protect: public support for flood defense over relocation in climate change adaptation
Freihardt, Jan; Buntaine, Mark; Bernauer, Thomas (2024)
Environmental Research Letters
Policy makers worldwide face tough choices over how to prioritize public funding for adaptation to climate change. One particularly difficult choice is whether to opt for policies that promote relocation away from flood risks or infrastructure investments that protect against flooding. Local communities commonly prefer protective infrastructure, but it is less obvious that the general public will support this approach due to the growing costs. We study public opinion on these adaptation approaches using a choice experiment with nationally representative samples in the United States and Germany (n = 2400 each). We asked participants to prioritize federal funding between two hypothetical, equally sized communities differing in their adaptation strategy, flood frequency, lives and economic assets at risk, economic vitality, geographic distance, and political orientation. In both countries, we find surprisingly strong support for protective infrastructure over relocation policies among the general public, even under conditions where relocation could be an attractive alternative for addressing the growing costs of protective infrastructure and rebuilding efforts.
Rivers of Change: A Story of Eroding Villages
Freihardt, Jan (2024)
Rivers of Change takes you on a captivating photographic journey, delving into one of the quintessential questions of the 21st century: How will human societies adapt to the rapidly accelerating climatic changes? This book, born out of an extensive research project, amplifies the voices of communities in Bangladesh living on the frontline of dramatic environmental changes. It not only showcases their vulnerability but also unveils their resilience in the face of repeated environmental shocks, forcing them to confront a crucial decision: to stay or to go?
When the river breaks the land: Environmental (im)mobility among rural households in Bangladesh
Freihardt, Jan (2023)
Global climate change is among the most important and severe challenges the international community has ever faced. Existing evidence shows that climatic changes will have far-reaching repercussions for ecosystems and humans alike. For instance, projections expect climate change to induce mass population movements due to hazards like droughts, sea level rise, or extreme weather events, particularly in low-income countries with limited capacity to protect themselves and adapt to such climatic changes. However, these projections are largely based on extrapolations from the population at risk of experiencing adverse climatic events. The recent literature therefore highlights that projections on climate-related migration should account for the possibility that people can adapt to changing climatic conditions. This is particularly relevant for slow-onset environmental changes such as droughts, salinization, or erosion, which individuals and societies can anticipate and adapt to. This dissertation contributes to a better understanding of whether, when, and how environmental changes lead to human migration. Theoretically, I link environmental changes to individual-level migration decisions by applying the aspirations-capabilities framework. I argue that exposure to environmental changes can increase someone’s aspirations to move away, while such exposure also has the potential of eroding the capability to move. People will move if they have both the aspiration and the capability to move. If one of the two is lacking, people remain immobile. Importantly, this concept also allows to differentiate “involuntary non-migrants” who would like to move away but lack the capability to do so from “voluntary non-migrants” who could move away but do not want to. Empirically, I employ a novel, self-collected panel data set of around 1700 household heads residing along the Jamuna River in northern Bangladesh, an area affected by riverbank erosion and flooding during the yearly recurring monsoon season. Through a multi-stage clustered sampling design, I obtained a sample representative of the rural population in the case study region. In a quasi-experimental approach, I surveyed respondents at a similar baseline risk of being affected before the environmental changes occurred. By re-interviewing both affected and unaffected respondents after the environmental changes have materialized, and both those who migrated and those who stayed, I can link any differences I observe between affected and unaffected respondents to the environmental shocks. This causal link makes a major empirical contribution to the literature on environmental migration that overwhelmingly applies secondary or retrospective data. In the empirical chapter I, I examine how the populations along the Jamuna perceive environmental and climatic changes and I compare these perceptions to objectively measured data. I find that perceptions of long-term temperature changes are more in line with meteorological evidence than those of precipitation. This finding is remarkable given that most of the respondents do not know the term climate change. Further, respondents grossly overestimate the extent of erosion that has occurred in their village in the previous year. Since human behavior is shaped by their perceptions rather than by objective data, this underlines the importance of considering people’s perceptions rather than exclusively relying on natural scientific data. Chapters II and III study how affectedness by riverbank erosion and flooding influences migration aspirations and migration behavior, respectively. The results suggest that riverbank erosion has a significant positive impact on both aspirations and the likelihood of migration. The effect of flood affectedness, by contrast, remains largely insignificant. This can be linked to the important role of flooding for the livelihood cycle of riverine populations, while erosion only has negative and potentially very detrimental effects on livelihoods. Lastly, chapter IV studies immobility in the context of environmental changes. I show that a majority (83%) of those who stay put after the monsoon season qualify as “voluntary/acquiescent non-migrants”, while 17% of the non-migrants can be classified as “involuntary”. Environmental shocks increase the respondents’ migration aspirations while reducing their capability to move. Hence, they might lead to “trapped populations” – a term which describes individuals who would like to move away but cannot. This dissertation provides valuable insights of broader relevance into whether and how societies react, or could react, to slow-onset climatic changes such as sea-level rise, drought, and soil/water salinity. Moreover, the methodology developed in the project can be applied to other cases and thereby inform prediction models of future climate-induced migration. Similarly, the findings could be utilized by institutional actors at local, national, and international levels when seeking to identify policy options to increase the adaptive capacity of populations vulnerable to climatic changes – supporting both those who would like to move and those who prefer to stay put.
Assessing and communicating erosion risk
Freihardt, Jan (2020)
Climate change will increase the frequency and intensity of many natural hazards such as storms or fires. Governments and public officials have the duty to protect their citizens and to prevent these hazards from turning into disasters. To do so effectively, they first need a scientific assessment of the disaster risk, which they communicate to affected people in the second step. This thesis examined both steps, by assessing past events of riverbank erosion in Bangladesh using radar imagery, and by investigating how the resulting disaster risk information could aid in risk communication. I could show that analyzing radar imagery on the Google Earth Engine (GEE) can assess riverbank erosion shortly after the end of the monsoon, and hence earlier than it would be possible with optical imagery. I developed an interactive online tool allowing the user to explore where riverbank erosion has occurred along Jamuna River in the last five monsoon seasons (2015-2019). Further, the source code of this tool is made publicly available, providing an option to apply the algorithm in other geographical settings. This can be attractive for authorities in low resource settings, given that the GEE can be used free of charge. In the second part of this study, I conducted an online experiment in seven coastal US states to investigate how aerial photographs containing information on past events of coastal erosion can help to decrease framing effects inherent in disaster risk communication. I found no framing effects in a risky choice situation and a goal framing setup, casting doubt on the strength of framing effects in real world scenarios. Adding the aerial photographs to the textual description of the scenario made respondents more risk seeking and increased their stated behavioral intention to take preventive measures against coastal erosion. The overall awareness among respondents about the issue of coastal erosion was high, resulting in few risky choices and high levels of stated behavioral intentions. Further research is required on the nature of framing effects in more realistic scenarios and on how people read and interpret aerial photographs containing information on past disaster events. In addition, I will test the findings from the online survey in a large scale household survey in Bangladesh.
Environmental Change and Migration Aspirations: Evidence from Bangladesh
Koubi, Vally; Freihardt, Jan; Rudolph, Lukas (2022)
SocArXiv
The argument that environmental change is an important driving force of migration has experienced a strong revival in the climate change context. We examine whether and how different environmental stressors aspire people to move. The analysis relies on newly collected, cross-sectional survey data of 1594 households residing in 36 villages along the 250 kilometers of the Jamuna River in Bangladesh – an area affected primarily by floods and riverbank erosion. The results show that long-term environmental events, i.e., riverbank erosion, increase aspirations for internal, permanent migration, while short-term environmental events, i.e., floods, do not affect migration aspirations. These results suggest that depending on the type of environmental change, people might prefer migrating rather than staying put and thus, they entail important policy implications regarding the effects of climate change on future internal migration flows.
Citizen Science in Switzerland: Taking Stock and Ways into the Future
Swiss Expert Group for Citizen Science; Stämpfli, Tiina; Zumthurm, Tizian; et al. (2024)
Swiss Academies Reports
In den letzten Jahren hat sich das Verhältnis zwischen Wissenschaft und Gesellschaft stark verändert. So ist Citizen Science in den Fokus gerückt und konnte sich dynamisch entwickeln und ausbreiten, auch in der Schweiz. Der vorliegende Bericht der Schweizer Expert:innengruppe für Citizen Science wurde partizipativ und mit Feedback aus der Community erarbeitet. Die Publikation stellt zum einen die vielfältigen und zahlreichen Initiativen, Projekte und Tools rund um Citizen Science in der Schweiz vor. Zum anderen werden Ziele und Massnahmen für verschiedene Akteure zu den vier Themen Mehrwert und Wirkung, Finanzierung, Ausbildung sowie Kommunikation und Sichtbarkeit formuliert.
Environmental change and migration aspirations: Evidence from Bangladesh
Rudolph, Lukas; Koubi, Vally; Freihardt, Jan (2025)
Global Environmental Change
The argument that environmental stress is an important driver of migration has gained renewed attention amidst increasing climatic changes. This study examines whether and how two distinct environmental stressors influence migration aspirations among affected populations. Our analysis relies on two waves of original survey data of 1,594 households residing in 36 villages along the 250 km of the Jamuna River in Bangladesh, an area heavily impacted by floods and riverbank erosion. The results reveal that riverbank erosion – a long-term environmental event causing permanent destruction – increases aspirations for internal, permanent migration by about 15 percentage points, 4 to 6 months after the occurrence. In contrast, sudden and short-term events, like floods, which have a more temporary impact, do not affect migration aspirations. These results suggest that the type of environmental event shapes adaptation strategies, with migration emerging as a viable response to more severe and lasting events such as erosion. This entails important policy implications regarding the effects of climate change on future patterns of internal migration and highlights that most affected individuals prefer to adapt to environmental stress in situ or within close proximity.

Publications 1 - 10 of 22

Jan Freihardt

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