Artificial light at night: a global disruptor of the night-time environment

Abstract

Light pollution is the alteration of the natural levels of darkness by an increased concentration of light particles in the night-time environment, resulting from human activity. Light pollution is profoundly changing the night-time environmental conditions across wide areas of the planet, and is a relevant stressor whose effects on life are being unveiled by a compelling body of research. In this paper, we briefly review the basic aspects of artificial light at night as a pollutant, describing its character, magnitude and extent, its worldwide distribution, its temporal and spectral change trends, as well as its dependence on current light production technologies and prevailing social uses of light. It is shown that the overall effects of light pollution are not restricted to local disturbances, but give rise to a global, multiscale disruption of the night-time environment. This article is part of the theme issue ‘Light pollution in complex ecological systems’.

Light pollution in complex ecological systems

“…It is important to recognize that as humans, we are not only responsible for light pollution but also integrated within the network of its effects on ecosystems ( figure 2 ). The introduction of artificial lighting, as highlighted by Bara & Falchi [ 11 ], has opened up the ‘nocturnal niche’ for human activities, offering benefits such as increased productivity, safety and convenience. However, alongside these advantages, artificial lighting also has direct negative effects on humans, including disruptions of the circadian rhythm, sleep disturbances and an increased risk of certain diseases like cancer [ 58 ].…”

“…The pollution of the night sky was recognized for the first time by astronomers in the first half of the twentieth century [ 9 ] as it started to interfere with their celestial observations and this phenomenon soon attracted the attention of a wider audience [ 10 ]. While artificial light at night (ALAN) is crucial for the everyday life of humans, Bara & Falchi [ 11 ] point out that only a tiny fraction of reflected light is used for human vision, while the rest pollutes the environment. With an estimated annual average increase of 9.6% (estimated based on citizen science data), light pollution is one of the most pressing drivers of current global change [ 12 ], and it has become increasingly clear that the loss of the night has serious psychological, health, socio-economic and ecological consequences.…”