Environments

There is scientific consensus that human activities have been altering the atmospheric composition and are a key driver of global climate and environmental changes since pre-industrial times (IPCC, 2013). It is a pressing priority to understand the Earth system response to atmospheric aerosol input from diverse sources, which so far remain one of the largest uncertainties in climate studies (Boucher et al., 2014; Forster et al., 2007). As the second most abundant component (in terms of mass) of atmospheric aerosols, mineral dust exerts tremendous impacts on Earth’s climate and environment through various interaction and feedback processes. Dust can also have beneficial effects where it deposits: Central and South American rain forests get most of their mineral nutrients from the Sahara; iron-poor ocean regions get iron; and dust in Hawaii increases plantain growth. In northern China as well as the midwestern United States, ancient dust storm deposits known as loess are highly fertile soils, but they are also a significant source of contemporary dust storms when soil-securing vegetation is disturbed. Accurate assessments of dust emission are of great importance to improvements in quantifying the diverse dust impacts.

The interdisciplinary study of oceans and human health is an area of increasing global importance. There is a growing body of evidence that the health of the oceans and that of humans are inextricably linked and that how we interact with and affect our oceans and seas will significantly influence our future on earth. Since the emergence of modern humans, the oceans have served as a source of culture, livelihood, expansion, trade, food, and other resources. However, the rapidly rising global population and the continuing alterations of the coastal environment are placing greater pressure on coastal seas and oceans. Negative human impacts, including pollution (chemical, microbial, material), habitat destruction (e.g., bottom trawling, dredging), and overfishing, affect not only ecosystem health, but also human health. Conversely, there is potential to promote human health and well-being through sustainable interactions with the coasts and oceans, such as the restoration and preservation of coastal and marine ecosystems. The study of oceans and human health is inherently interdisciplinary, bringing together the natural and social sciences as well as diverse stakeholder communities (including fishers, recreational users, private enterprise, and policymakers). Reviewing history and policy with regard to oceans and human health, in addition to known and potential risks and benefits, provides insights into new areas and avenues of global cooperation, with the possibility for collaboratively addressing the local and global challenges of our interactions with the oceans, both now and in the future.

Towns and cities generally exhibit higher temperatures than rural areas for a number of reasons, including the effect that urban materials have on the natural balance of incoming and outgoing energy at the surface level, the shape and geometry of buildings, and the impact of anthropogenic heating. This localized heating means that towns and cities are often described as urban heat islands (UHIs). Urbanized areas modify local temperatures, but also other meteorological variables such as wind speed and direction and rainfall patterns. The magnitude of the UHI for a given town or city tends to scale with the size of population, although smaller towns of just thousands of inhabitants can have an appreciable UHI effect. The UHI “intensity” (the difference in temperature between a city center and a rural reference point outside the city) is on the order of a few degrees Celsius on average, but can peak at as much as 10°C in larger cities, given the right conditions. UHIs tend to be enhanced during heatwaves, when there is lots of sunshine and a lack of wind to provide ventilation and disperse the warm air. The UHI is most pronounced at night, when rural areas tend to be cooler than cities and urban materials radiate the energy they have stored during the day into the local atmosphere. As well as affecting local weather patterns and interacting with local air pollution, the UHI can directly affect health through heat exposure, which can exacerbate minor illnesses, affect occupational performance, or increase the risk of hospitalization and even death. Urban populations can face serious risks to health during heatwaves whereby the heat associated with the UHI contributes additional warming. Heat-related health risks are likely to increase in future against a background of climate change and increasing urbanization throughout much of the world. However, there are ways to reduce urban temperatures and avoid some of the health impacts of the UHI through behavioral changes, modification of buildings, or by urban scale interventions. It is important to understand the physical properties of the UHI and its impact on health to evaluate the potential for interventions to reduce heat-related impacts.