Mapping ecological risks from the colour spectrum of artificial nighttime lighting using astronaut images of the earth

Daily, lunar and seasonal cycles of natural light have occurred across the Earth's surface since the first emergence of life and are key features of the natural environment that have driven the development of biological phenomena from the molecule to the ecosystem. These natural patterns have, however, over the last 100 years come to be greatly disrupted through the introduction of artificial light into the nighttime environment. This disruption derives from a range of sources, including street lighting, advertising lighting, architectural lighting, security lighting, domestic lighting and vehicle lighting. Indeed, artificial nighttime lighting is already estimated to be experienced directly and indirectly (through skyglow - scattering by molecules or aerosols in the atmosphere of artificial nighttime light that is emitted or reflected upwards) by more than 20% of the global land area and to be growing at about 6% per year. Images of the earth at night acquired by satellites and manned space missions frequently illustrate the extent of the problem.

The introduction of artificial light into the nighttime environment has provided significant and substantial benefits to humankind. But, given that biological systems are fundamentally shaped by light, there have inevitably been a wide array of environmental impacts. Studies have highlighted consequences of artificial nighttime light for the physiology, foraging, daily movements, migratory behaviour, reproduction, and mortality of individual organisms, for the abundance and distribution of species, and for the composition and functioning of communities. However, the spatial pattern and variation over time of these effects remain poorly understood. In major part this is because whilst the responses are commonly dependent on the different wavelengths of artificial nighttime lighting (perceived as colour), data on how this varies at geographic scales has largely been lacking. This means that it is difficult to identify those areas in which the environmental impacts of artificial lighting are of greatest concern and where attention to optimizing the trade-offs between human benefits and environmental impacts should be focused. This is particularly significant at a time of large scale and rapid introduction of new lighting technology and use of 'smart illumination'; many street and other lighting systems are moving to 'whiter' lights, commonly using light-emitting diodes (LEDs), and central management systems are increasingly enabling more flexible approaches to the implementation of public lighting.

In this project we will resolve this problem, and determine the likely severity across Europe of an array of ecological impacts of artificial lighting of the nighttime environment using data from a novel and largely untapped source, the colour images taken using conventional SLR cameras by astronauts aboard the International Space Station.

Much contention surrounds the most appropriate levels of artificial lighting of the nighttime environment, and how best to deliver these. On the one hand, there is much evidence of negative environmental impacts, including on human health and wellbeing, and on wildlife. On the other hand, such lighting brings substantial human benefit, and even though effects on levels of crime and vehicular accidents are complex, there is widespread public perception that such effects are strongly beneficial. Indeed, proposals and attempts to cut levels of street lighting have often met with marked public opposition. This project is therefore clearly of value to two groups of non-academic stakeholders, the general public, and those more directly concerned with the provision of artificial nighttime lighting (government, lighting contractors & environmental NGOs).
(i) General public - the project provides an opportunity to use the case of artificial nighttime lighting to improve public understanding of the trade-offs that lie at the heart of many policy decisions, and to encourage a scientifically literate citizenry that understands the profound and rapid effects that arise from anthropogenic environmental changes. The research project will provide a tangible link between the environmental change created by artificial nighttime lighting and the responses of organisms, and we will take advantage of these data to develop teaching materials on the nature of science and policy, relating to environmental change impacts on biological systems, directed to secondary school students, and to work with cohorts of such students through a Teacher Affiliate program.
(ii) Government, lighting contractors & environmental NGOs - a number of governmental and non-governmental groups have a significant interest in improved understanding of the likely environmental consequences of artificial nighttime lighting, for purposes ranging from shaping their own public engagement programs to making better public lighting policy and on-the-ground management decisions. One of the challenges faced lies in the undoubted complexity of the issues and the associated uncertainties. In particular, the vital importance of the spectrum of lighting emissions for its environmental impacts is not well understood, and as a consequence, opportunities for mitigating impacts through changes in lighting policies may be missed. We will use the work of the research project to improve understanding of the role of the spectrum of artificial nighttime lighting change in the resultant environmental impacts, to explore together what this means for environmental policy and planning, and how best practice can most effectively be promulgated.