<\/p>\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t\t\t\tWhy light pollution?\n\t\t\t\t\t\t

Light pollution is increasing globally, with an estimated 80% of the world's population currently living under a \u201clit sky\u201d - a figure closer to 99% in Europe and North America. The amount of artificial light on the Earth\u2019s surface is increasing by at least 2% annually, while the use of artificial light at night is substantially increasing all over the world. To understand why light pollution is a problem, we first need to understand what it is. <\/p>\t\t\t\t\t\t\t\t\t\t\t\n\t<\/section>\t\t\n\t\t\t\t\tWhat is light pollution?\n\t\t\t\t\t

According to CMS Resolution 13.5, \u201clight pollution refers to artificial light that alters the natural patterns of light and dark in ecosystems\u201d. Artificial light is used to illuminate streets, commercial, residential and industrial properties, particularly in cities. Although artificial light is often used for security or safety reasons, monuments, churches, bridges and other landmarks may be illuminated at night for aesthetic purposes. <\/p>

Light pollution and wildlife<\/b><\/p>

The increasing use of lighting has modified the natural environment dramatically impacting wild animals, plants and the functioning of entire ecosystems. There is a lack of information regarding how artificial light at night impacts most species. Research so far has largely focused on some species of birds, bats, marine turtles and insects. As they are nocturnal, bats are particularly susceptible to light pollution which can disrupt their foraging, commuting, drinking, roosting and migrating behaviors. Light pollution can affect adult female marine turtles when they come ashore to nest, and hatchling turtles may be unable to find their way to the sea or to disperse successfully to the open ocean under conditions where light pollution is present. Light pollution is implicated, alongside other drivers such as pesticide use, in the massive global decline in insects. The physiology, behavior and fitness of diurnal and nocturnal insects can all be affected, with knock-on effects on pollination and food webs.\u00a0\u00a0<\/p>

Further research is needed to investigate how light pollution impacts other groups of animals including fish, reptiles (other than turtles) and mammals (other than bats).<\/p>\n\t\t\tHow does light pollution impact migratory birds?\n\t\t

Light pollution can alter birds' behaviors, including migration, foraging and vocal communication. It also affects their activity levels and their energy expenditures. Migratory birds are particularly exposed to light pollution, especially those which migrate at night. Light pollution attracts and disorients nocturnally migrating birds, which may end up circling in illuminated areas. This unnatural light-induced behavior can mean they end up depleting their energy reserves and puts them at risk of exhaustion, predation and lethal collision.<\/p>\t\t\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\n\t\t

Satellite monitoring revealed that from 2012 to 2016,<\/p>

artificially lit outdoor areas increased by 2.2% per year<\/strong>. Recent studies show that this number could be much greater.<\/p>

Light pollution can change birds' migration patterns, foraging behaviors, and vocal communication.\u00a0<\/p>

Each year, light pollution contributes to the deaths of millions of birds from collisions with buildings and other infrastructure. Long distance migrants, such as the blackpoll warbler (Setophaga striata<\/i>), the Asian stubtail (Urosphena squameiceps<\/i>) and the oriental plover (Charadrius veredus<\/i>), may start and end their migrations in areas with relatively low levels of light pollution, but during migration they may fly over areas of intense urban development where they experience high levels of artificial light. Migrating birds can be attracted to lights, particularly when there is low cloud, fog or rain and they are flying at lower altitudes.<\/p>\t\t\n\t\t\t\t\tCities and light pollution\n\t\t\t\t\t