When we think of pollution, it’s not often that we consider light to be in that category. But in fact, artificial light is considered an environmental pollutant, as it throws off circadian rhythms and threatens nocturnal animals, plants and microorganisms. Now, an international study published in the journal Science Advances finds that artificial lights are increasing “loss of night,” with the effects particularly strong in certain nations.
In order to determine whether the use of outdoor light is continuing to grow exponentially, Christopher Kyba and colleagues analyzed data acquired by the Visible Infrared Imaging Radiometer (VIIRS), which is a satellite sensor with a spatial resolution of 750 meters. Through this analysis, they determined that the Earth’s artificially lit outdoor areas grew by over 2 percent (2.2%) per year from 2012 to 2016.
Data showed that these lighting changes were highly variable between countries – some nations greatly exceeded the global rate, while a few experienced decreases in radiance. Two of the countries that had these decreases are Yemen and Syria, which are currently in turmoil with widespread war.
In the world’s brightest nations (referring to light, not necessarily intelligence) such as the United States and Spain, the radiance levels remained stable. In South America, Africa, and Asia, most nations experienced growth in artificial light. Overall, these results show that the global demand for outdoor nighttime light has yet to be met. Furthermore, despite the increases in solid-state lighting (such as LEDs), short-term decreases in related energy consumption appear unlikely.
The researchers also note that the growth in nighttime light from 2012 to 2016 were a close match to the global rise in gross domestic product (GDP). They believe that this finding suggests that access to solid-state lighting does not decrease global energy consumption for outdoor light, which has been an international goal.
These increases – and projections of further increases – in artificial light have significance for everything from our economic policies to our environmental policies. While discovering what areas are experiencing the greatest effects is key, determining how to lessen these effects will be crucial.