Where human settlements abut or intermix with wildlands, people may encounter animals that host zoonotic pathogens which can spillover to cause human disease. Known as the wildland-urban interface (WUI), this zone occupies around 5% of the Earth's surface and is home to 3.5 billion people. The rapid spread of SARS-CoV-2 has demonstrated the importance of understanding risk factors for disease among an increasingly urbanized population. However, the contribution of the WUI to zoonotic disease risk is poorly understood. Here, we show that low-level host richness occurs throughout most of the global WUI, and 20% of the human WUI population live in zones of particularly high zoonotic potential, where more than 20 host species could occur. Zones of high zoonotic potential are concentrated in low-middle-income countries (LMICs) across equatorial Africa, Brazil, Central America, and Southeast Asia where vulnerability is further elevated by widespread poverty, inadequate housing, and lack of easily accessible healthcare. Three of four people living in WUIs with high host richness (520 million people) are in LMICs. Of this population, 35% (183 million) live in and around cities in West, East, and South Africa. This means that WUI-based populations of LMICs may face the double threat of high zoonotic potential and vulnerability to disease. Our results identify global priorities for monitoring exposure to zoonotic diseases in the rapidly expanding WUI.

Over the next 30 years, the expansion of cities will threaten global biodiversity unless we change the way that they are built. Greener cities can become part of the solution to the global biodiversity crisis.

Significance Understanding the impacts of urbanization and the associated urban land expansion on species is vital for informed urban planning that minimizes biodiversity loss. Predicting habitat that will be lost to urban land expansion for over 30,000 species under three different future scenarios, we find that up to 855 species are directly threatened due to unmitigated urbanization. Our projections pinpoint rapidly urbanizing regions of sub-Saharan Africa, South America, Mesoamerica, and Southeast Asia where, without careful planning, urbanization is expected to cause particularly large biodiversity loss. Our findings highlight the urgent need for an increased focus on urban land in global conservation strategies and identify high-priority areas for this engagement.

An understanding of tropical hydroclimate variability, the associated drivers and how it is likely to change is a major scientific and societal challenge that is acutely hampered by short instrumental records. We present a 246year tree-ring drought reconstruction of the Standardised Precipitation Evaporation Index (SPEI) for monsoonal northern Australia for the end of the wet season (March-May; MAM). This reconstruction extends the instrumental record back by 150 years. Around one third of total annual rainfall falls during MAM, making it a crucial component of the monsoonal cycle. MAM is also the season most impacted by the differential decay process of Central Pacific (as opposed to Western Pacific) El Nino events that are linked with dry conditions over northern and northwestern Australia more generally. Our reconstruction therefore provides an opportunity to consider how central Pacific variability has modulated MAM hydroclimate in Australia's monsoonal north over the past two and a half centuries. We found that MAM hydroclimate extremes in the region have a strong, but asymmetric relationship with central Pacific sea surface temperatures (SSTs) and ENSO indices. Extremely wet MAMs in monsoonal north Australia were associated with cooler SSTs, above average rainfall across much of Australia, and often coincided with La Nina events. The spatial relationship between dry extremes and Pacific SSTs during dry events was generally, but weakly, consistent with the SST signature of central Pacific El Nino events. The association between reconstructed dry extremes in the monsoonal north and dry conditions across the rest of Australia is also less extensive and weaker than for wet events. Results suggest that more extreme wet events in the Australian monsoonal north likely reflect cool central Pacific SSTs and later termination of the Australian monsoon. Consecutive years with extremely dry MAMs became more frequent over the latter part of the 20th Century while the probability of an extreme dry MAM followed by an extreme wet MAM the next year peaked in the mid 20th Century and has since declined.

By 2030, an additional 1.2 billion people are forecast in urban areas globally. We review the scientific literature (n = 922 studies) to assess direct and indirect impacts of urban growth on habitat and biodiversity. Direct impacts are cumulatively substantial, with 290,000 km2 of natural habitat forecast to be converted to urban land uses between 2000 and 2030. Studies of direct impact are disproportionately from high-income countries. Indirect urban impacts on biodiversity, such as food consumption, affect a greater area than direct impacts, but comparatively few studies (34%) have quantified urban indirect impacts on biodiversity. The world is urbanizing. This Review assesses impacts of urban growth on habitat and biodiversity, finding direct impacts more in high-income countries while indirect impacts affect more land but are lesser studied.

Abstract It is well established that local environmental conditions directly impact human health. As the world population and land surface both become increasingly urban, understanding the health consequences of urban land use–driven environmental change is critically important. Understanding these relationships is a necessary condition in planning urban development in ways that may be co-beneficial for both the environment and human health. Environmental influences on health include but are not limited to air pollution and asthma, access to green space and mental and physical health, and water pollution and water-borne diseases. However, it is not only the local environment that affects health; the regional and global environments also contribute to health outcomes. This chapter explores the interdependencies between regional and global environments and human health, using urban land use as an analytical lens.

Spatial heterogeneity in the intensity of past disturbances has directly influenced the structure and composition of present-day forests around the world. In south-eastern Australia infrequent, high-intensity wildfires are a major part of the historical disturbance regime. While these fires are often assumed to produce even-aged stands, spatial heterogeneity in fire intensity due to highly variable topography may lead to more complex forest age structures. Our study describes the influence of disturbance on the age structure and dynamics of a mosaic of tall, open eucalypt forest, cool temperate rainforest and mixed species forest surrounding Bellel Creek in the Central Highlands of Victoria using dendrochronological techniques. We were particularly interested in the impacts of the 1939 Black Friday fire and its effects on forest age structure and subsequent stand development patterns. Within our study site tall open forest displayed two distinct age cohorts: (i) trees that established immediately after the 1939 fire and accounted for the majority of individuals in the forest, and (ii) scattered groups of older trees estimated to be approximately 200-250 years old. Cool temperate rainforest and mixed forest were also dominated by the post-1939 fire age cohort. However, a greater proportion of trees in these forest types survived the 1939 fire relative to the tall open forest. The impact of the 1939 fire on the growth of surviving trees was highly variable but generally short-lived. In most cases growth decreased after the 1939 fire, but generally returned to prefire levels within 1-3 years. Non-fire disturbances were limited to small-scale branch- and tree-fall events, although the extreme snowstorm of 1977 appears to have caused extensive damage to rainforest communities. Our study demonstrates the opportunities for dendroecological studies to reconstruct historical dynamics and disturbance patterns in Australian forests and provides important insights into variation in landscape-scale fire impacts and their effect on subsequent forest development patterns.