Among the countless effects of anthropogenic activities, perhaps one of the lesser known problems is the diminishing number of our dark sky preserves - facing threats from land-use practices to air pollution.
From allowing animals to naturally hunt and move around in the dark, helping scientists observe the space beyond us, simply offering a camping experience under an unadulterated view of the night sky, dark sky preserves serve various purposes. That is why the International Dark Sky Association (IDA) has been working worldwide, promoting the importance of these natural resources and offering support in conserving them.
The Campaign to Conserve Pieces of the Dark Sky
The IDA traced its origins to 1988, when astronomers David Crawford and Tim Hunter observed the rising challenges of monitoring celestial bodies because the night sky has become too bright. This phenomenon is technically known as excessive skyglow and is caused by the dispersed light (usually from artificial sources) that remains trapped in the atmosphere. It led the two to create the nonprofit incorporated in 1988, with the mission "to preserve and protect the night time environment and our heritage of dark skies through quality outdoor lighting."
Dark sky preserves are usually locations surrounding a natural park or an observatory, with controlled or restricted light pollution. A 2018 article from the Royal Astronomical Society of Canada (RASC) presents guidelines in outdoor lighting for these preserves, considering various factors such as wildlife response and sensitivity to artificial light at night, or ALAN. The stricter standards have considered the skyglow from surrounding urban areas, which was assessed by the RASC, guiding their guidelines.
Since then, the IDA has worked to recognize and accredit Dark Sky locations around the world and standardize terminologies relating to these areas to guide conservation efforts. Dark Sky Preserves are classified as either a reserve (ISDR), park (ISDP), and sanctuary (ISDS). There are also international dark sky communities and urban night sky places.
The Far-Reaching Effects of Artificial Light
A significant body of research has examined the effect of artificial light at night on natural life - from humans, animals, and even plants. One example is a 2017 article from PNAS, which reports how urban light installations adversely affect bird migration, especially those that migrate at night. While researchers suggested further studies to isolate the effect of ambient conditions, they demonstrated how artificial light disorients migrating birds, for example.
On the other hand, artificial light also hampers astronomical studies, which prompted Crawford and Hunter to protect natural darkness and conserve dark sky preserves. According to the International Astronomical Union, "the most obvious everyday manifestation of light pollution is in the increasing illumination of our night sky and the subsequent difficulties in observing astronomical objects from polluted locations." It also explains that light from artificial light sources that are poorly designed and incorrectly directed shines light into the sky, where it is scattered by air molecules and suspended aerosol particles.
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