Life on our planet has evolved for millions of years in a rhythmic environment dictated by sunlight, moonlight and starlight. Consequently, organisms have developed adaptations to use light as a source of energy (eg photosynthesis), temporal information (eg circadian, circannual and circatidal rhythms) and spatial orientation (eg navigating using stars). However, the invention of artificial light, and specifically its widespread use in the outdoor and indoor environment, is increasingly recognised as a threat to these long-evolved biological processes .
In the last decade research on the ecological impacts of artificial light at night (ALAN) has blossomed. ALAN has been shown to affect genetic, physiological and behavioural responses of a wide-range of taxa . Perhaps the most recognised impact is that on insects, and particularly on phototactic species which are attracted to artificial light sources where they suffer from high mortality due to increased predation, collision or exhaustion . Effects on individual responses of insects have been recently highlighted to scale-up to population level consequences, providing one potential ecological mechanism to explain the insect apocalypse we are currently experiencing [4, 5].
Losing insects, among many other species that are known to be negatively affected by ALAN, has a cost for the healthy functioning of the natural environment, and consequently for the ecosystem services it provides . Several insect species provide us with essential services. For instance, pollinators are key to maintain plant diversity and productivity, including that of crops. Insects also perform decomposition and pest control, other essential ecosystem services. Moreover, insects are often a key resource for taxa higher up on the food web, such as vertebrates, which also provide essential services to our society. Thus, ALAN may have an economic cost through the erosion of the natural environment, but this has never been quantified .
The erosion of green and blue spaces has been shown to impact not only biodiversity, but also human well-being . These spaces, and particularly public ones in urban areas, represent the only regular daily opportunity for an increasing urban population to interact with nature. This interaction has been shown to have measurable physical and psychological benefits, and these benefits increase with increasing biodiversity . If ALAN negatively affects biodiversity, then it is conceivable to hypothesise that it will also have detrimental impacts on human well-being. Moreover, light pollution may also have direct effects on well-being, for instance because it can interfere with the appreciation of the nocturnal natural environment (eg stargazing), with sensory perception and with sleep quality . However, the indirect and/or direct relationship of ALAN with human well-being have been largely overlooked.
Despite the increasing evidence of the diverse impacts of ALAN, these impacts should be relatively easy to mitigate. Among effective mitigation strategies are: i) reducing the intensity of unnecessarily bright illumination, ii) shifting the colour spectrum towards red wavelengths, iii) turning off lights when and where they are not needed, iv) point illumination only where needed and never towards the sky . The current widespread conversion of old incandescent illumination to energy and cost-efficient LEDs offers the chance to implement smart mitigation strategies, but this is too often a missed opportunity . We argue that quantifying the net environmental and economic benefit of smart lighting will support policy-makers to legislate accordingly, and city councils to more widely adopt such strategies.
The aim of this project is to gain a holistic view of the effects of light pollution on biodiversity, ecosystem services and human well-being. Moreover, we also aim to quantify the effectiveness of alternative lighting strategies in reducing the environmental and socioeconomic costs of light pollution. Because of the transdisciplinary nature of the work, the student will be exposed to different research backgrounds and will interact with a diverse team of supervisors. This will offer the possibility to develop a highly relevant set of skills across ecology, environmental science and environmental economics. There will also be ample opportunities to develop the project in different directions by expanding the network of collaborators. For instance, additional economic and environmental benefits of minimising light pollution could be quantified, such as those derived by the reduced carbon footprint of producing and consuming less energy.