Urban heat stress: novel survey suggests health and fitness as future avenue for research and adaptation strategies

Extreme heat has tremendous adverse effects on human health. Heat stress is expected to further increase due to urbanization, an aging population, and global warming. Previous research has identified correlations between extreme heat and mortality. However, the underlying physical, behavioral, environmental, and social risk factors remain largely unknown and comprehensive quantitative investigation on an individual level is lacking. We conducted a new cross-sectional household questionnaire survey to analyze individual heat impairment (self-assessed and reported symptoms) and a large set of potential risk factors in the city of Berlin, Germany. This unique dataset (n = 474) allows for the investigation of new relationships, especially between health/fitness and urban heat stress. Our analysis found previously undocumented associations, leading us to generate new hypotheses for future research: various health/fitness variables returned the strongest associations with individual heat stress. Our primary hypothesis is that age, the most commonly used risk factor, is outperformed by health/fitness as a dominant risk factor. Related variables seem to more accurately represent humans' cardiovascular capacity to handle elevated temperature. Among them, active travel was associated with reduced heat stress. We observed statistical associations for heat exposure regarding the individual living space but not for the neighborhood environment. Heat stress research should further investigate individual risk factors of heat stress using quantitative methodologies. It should focus more on health and fitness and systematically explore their role in adaptation strategies. The potential of health and fitness to reduce urban heat stress risk means that encouraging active travel could be an effective adaptation strategy. Through reduced CO2 emissions from urban transport, societies could reap double rewards by addressing two root causes of urban heat stress: population health and global warming.Deutsche Forschungsgemeinschaft 10.13039/501100001659Peer Reviewe

Quantification of heat-stress related mortality hazard, vulnerability and risk in Berlin, Germany

Many studies have addressed the challenge of heat stress for human health in recent years. However, appropriate concepts and methods for quantifying heat-stress hazards, vulnerabilities and risks are yet under development. The objective of this study is to test the applicability of a risk concept and associated event-based risk-analysis method for quantifying heat-stress related mortality. The study reveals that about 5 % of all deaths between 2001 and 2010 in Ber­lin can statistically be related to elevated air temperatures. Most of the affected people are 65 years or older, while the mortality of people below 65 years shows only weak statistical correlation to air temperature. Mean daily air tempera­ture was best suitable for risk analysis. The results demonstrate that the novel approach for quantitative risk analysis delivers statistically highly significant results on the city scale when analysing heat stress on an event basis. Performing the risk analysis on a spatially distributed data basis for city districts would allow to account for spatial variations of ur­ban climates and demographic properties. Using indoor climate data is expected to provide new insight into heat-stress related mortality risks, particularly for highly vulnerable persons like elderly persons or patients residing in hospitals

Urban heat stress: novel survey suggests health and fitness as future avenue for research and adaptation strategies

Extreme heat has tremendous adverse effects on human health. Heat stress is expected to further increase due to urbanization, an aging population, and global warming. Previous research has identified correlations between extreme heat and mortality. However, the underlying physical, behavioral, environmental, and social risk factors remain largely unknown and comprehensive quantitative investigation on an individual level is lacking. We conducted a new cross-sectional household questionnaire survey to analyze individual heat impairment (self-assessed and reported symptoms) and a large set of potential risk factors in the city of Berlin, Germany. This unique dataset (n = 474) allows for the investigation of new relationships, especially between health/fitness and urban heat stress. Our analysis found previously undocumented associations, leading us to generate new hypotheses for future research: various health/fitness variables returned the strongest associations with individual heat stress. Our primary hypothesis is that age, the most commonly used risk factor, is outperformed by health/fitness as a dominant risk factor. Related variables seem to more accurately represent humans’ cardiovascular capacity to handle elevated temperature. Among them, active travel was associated with reduced heat stress. We observed statistical associations for heat exposure regarding the individual living space but not for the neighborhood environment. Heat stress research should further investigate individual risk factors of heat stress using quantitative methodologies. It should focus more on health and fitness and systematically explore their role in adaptation strategies. The potential of health and fitness to reduce urban heat stress risk means that encouraging active travel could be an effective adaptation strategy. Through reduced CO2 emissions from urban transport, societies could reap double rewards by addressing two root causes of urban heat stress: population health and global warming

Landnutzungsmodellierung und Bewertung von Ökosystemdienstleistungen unter Wachstums- und Schrumpfungsbedingungen : das Fallbeispiel Berlin

Die heutigen politischen Entscheidungsträger müssen sich im Hinblick auf die begrenzte Belastbarkeit der Umwelt und die Grenzen menschlicher Belastbarkeit der Herausforderung stellen, die komplexen Wechselwirkungen zwischen menschlichem Handeln und der natürlichen Umwelt zu verstehen und zu gestalten. Dies ist besonders in städtischen Regionen, in denen die erhöhte Umweltbelastung evident ist, von hoher Relevanz, was am Beispiel des kontinuierlichen globalen Rückgangs von Ökosystemdienstleistungen in Folge der anhaltenden Verstädterung deutlich wird. Zukünftige politische Entscheidungen können nur zielführend sein, wenn sie integrativ in dem vielseitigen Ursache-Wirkungs-Gefüge städtischer Veränderungen betrachtet werden. Für solch ein Bestreben erscheint ein systemischer Ansatz, wie er in dieser Dissertation gewählt wurde, vielversprechend. Das Ziel dieser Doktorarbeit ist es, die wesentlichen Prozesse und Dynamiken, die charakteristisch sind für das komplexe System einer Stadt, in einem kombinierten Modellansatz abzubilden. Zu diesem Zweck wird ein demographisch angetriebenes Modell zur Berechnung der Wohnnachfrage und des Wohnangebotes mit einem räumlich expliziten Landnutzungsmodell verknüpft. Die Auswirkungen von Landnutzungsänderung auf die städtische Struktur, sowie auf das Angebot von Ökosystemdienstleistungen werden mit Hilfe von zum Teil neu entwickelter Indikatoren untersucht. Zusätzlich wird das Modell genutzt um das städtische Systemverständnis unter Verwendung von Szenariosimulationen voranzutreiben und szenariospezifische Auswirkungen auf die Stadtstruktur und das Angebot von Ökosystemdienstleistungen zu ermitteln. Die Szenarien basieren auf nicht-räumliche, demographische Veränderungstrends, z.B. Bevölkerungswachstum, -schrumpfung oder Überalterung; sowie räumliche Trends, z.B. durch veränderte Nachfragepräferenzen oder veränderten Planungsvorgaben. Das Untersuchungsgebiet stellt die Metropolregion Berlin dar. Dem kombinierten Modell wird aufgrund der verbesserten Anbindung von kausalen Triebkräften und der Nutzung eines fortschrittlichen Verfahrens zur Berechnung von Wohnstandortentscheidungen, eine überzeugende Reproduktion von Landnutzungsänderung nachgewiesen. Städtische Prozesse der Suburbanisierung und der Reurbanisierung können abgebildet werden, durch die Integration simultan ablaufender Wachstums- und Schrumpfungsprozesse in unterschiedlichen Wohnnutzungstypen. Mit Hilfe von verschiedenen Simulationsergebnissen wird nachgewiesen, dass die Zunahme der Bevölkerung, sowie die Alterung der Bevölkerung den Flächenverbrauch, die Fragmentierung der Landschaft und den Verlust an Ökosystemdienstleistungen deutlich erhöhen. Im Gegensatz dazu können diese Kenngrößen durch Bevölkerungsrückgang und der Veränderung von Wohnpräferenzen hin zu zentraleren Wohnlagen verringert werden. Darüber hinaus wird gezeigt, welche Landnutzungsänderungen sich besonders gut, bzw. besonders schlecht auf das Angebot von Ökosystemdienstleistungen und deren Verflechtungen (wie Synergien oder Trade-offs) auswirken. Die Doktorarbeit schlussfolgert mit der detaillierten Beschreibung der systematischen Verknüpfungen von menschlichen Entscheidungen, stadtstrukturellen Veränderungen und Umweltwirkungen, was schließlich in einer Wirkungskette städtischer Systemdynamiken mündet.Today’s political decision makers are challenged to tackle the complex interactions between human activities and the natural environment within the context of limited environmental and human resilience. This becomes especially important in urban regions, where environmental effects are particularly evident, as indicated for instance by a continuous global decline of ecosystem services (ES) due to the increase of urban areas. Future decision-making can only be effectively promoted if the multiple cause-effect relationships driving urban and ES change are understood. For this purpose, a systemic approach seems promising and was chosen in this dissertation thesis. The aim of this thesis is to provide a combined model approach that is able to reveal the currently observed urban processes and dynamics which characterize the complex urban system. To this end, a demographically-driven residential demand and supply model is linked to a spatially explicit land-use change (LUC) model. The effects of LUC on the urban pattern and ES provisioning are analyzed using partly newly developed indicators. Additionally, the chosen model approach should serve to increase understanding of the urban system. In order to accomplish this, varying scenarios were developed to determine their respective effects on the urban pattern and ES, including both aspatial demographic shift trends such as population growth, shrinkage and population aging, as well as spatial trends such as demand preference and planning shifts. The case study presents the Berlin metropolitan region. The combined model provides a very satisfactory reproduction of land-use change by improving the causal relations of LUC drivers within sophisticated residential choice mechanisms. It is able to reproduce the simultaneous growth and shrinkage in varying residential types, and includes the processes of reurbanization and suburbanization. Future simulations indicated that population growth and population aging—expedited by population shrinkage—increases land consumption, landscape fragmentation and ES loss. In contrast, population shrinkage and shifting preferences towards reurbanization can effectively reduce these same aspects. It could be shown which particular land-use transitions most significantly affect ES degradation or improvement, and how they relate to ES linkages in terms of synergies and trade-offs. The thesis concludes with a detailed description of systematic linkages regarding human decisions, the urban pattern and environmental effects, resulting in a functional chain of urban system dynamics and depicting the strength of the connection between the relevant system parameters