Urban Health: Evidence, Challenges, and Directions

Urbanization is one of the most important demographic shifts worldwide during the past century and represents a substantial change from how most of the world’s population has lived for the past several thousand years. The study of urban health considers how characteristics of the urban environment may affect population health. This paper reviews the empirical research assessing urban living’s impact on population health and our rationale for considering the study of urban health as a distinct field of inquiry. The key factors affecting health in cities can be considered within three broad themes: the physical environment, the social environment, and access to health and social services. The methodologic and conceptual challenges facing the study of urban health, arising both from the limitations of the research to date and from the complexities inherent in assessing the relations among complex urban systems, disease causation, and health are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/40323/2/Galea_Urban Health - Evidence, Challenges, and Directions_2005.pd

Diurnal to interannual rainfall δ^(18)O variations in northern Borneo driven by regional hydrology

The relationship between climate variability and rainfall oxygen isotopic (δ^(18)O) variability is poorly constrained, especially in the tropics, where many key paleoclimate records rely on past rainfall isotopes as proxies for hydroclimate. Here we present a daily-resolved, 5-yr-long timeseries of rainfall δ^(18)O from Gunung Mulu National Park, located in northern Borneo (4°N, 114°E) in the heart of the West Pacific Warm Pool, and compare it to local and regional climatic variables. Daily rainfall δ^(18)O values range from +0.7‰ to −18.5‰ and exhibit a weak but significant inverse relationship with daily local precipitation amount (R=−0.19, p<0.05), consistent with the tropical amount effect. Day-to-day δ^(18)O variability at Mulu is best correlated to regional precipitation amount averaged over the preceding week (R=−0.64, p<0.01). The inverse relationship between Mulu rainfall δ^(18)O and local (regional) precipitation amount increases with increased temporal averaging, reaching R=−0.56 (R=−0.72) on monthly timescales. Large, negative, multi-day rainfall δ^(18)O anomalies of up to 16‰ occur every 30–90 days and are closely associated with wet phases of the intraseasonal Madden–Julian Oscillation. A weak, semi-annual seasonal cycle in rainfall δ^(18)O of 2–3‰ bears little resemblance to seasonal precipitation variability, pointing to a complex sequence of moisture sources and/or trajectories over the course of the year. Interannual rainfall δ^(18)O variations of 6–8‰ are significantly correlated with indices of the El Niño Southern Oscillation, with increased rainfall δ^(18)O during relatively dry El Niño conditions, and vice versa during La Nina events. We find that Mulu rainfall δ^(18)O outperforms Mulu precipitation amount as a tracer of basin-scale climate variability, highlighting the time- and space-integrative nature of rainfall δ^(18)O. Taken together, our results suggest that rainfall δ^(18)O variability at Mulu is significantly influenced by the strength of regional convective activity. As such, our study provides further empirical support for the interpretation of δ^(18)O-based paleo-reconstructions from northern Borneo stalagmites as robust indicators of regional-scale hydroclimate variability, where higher δ^(18)O reflects regional drying