Almost half of the Earth's surface affected by light pollution
Light pollution is increasing around the world. A research team is calling for better technical means to continuously measure the phenomenon.
In many places, it no longer gets really dark due to artificial light. A problem for people and the environment, warn researchers.
(Image: Sander van der Werf/ Shutterstock.com)
Almost half of the Earth's surface is affected by light pollution caused by artificial lighting. This is the result of a study by the international research team "Nightwatch Consortium". The scientists warn that the night sky must be preserved for future generations. However, this requires more technical progress.
Light pollution has increased: 80 percent of the total population now lives under a light-polluted sky, the researchers write. The team has published its findings as part of a European Space Agency (ESA) project in an article in the journal "Nature Reviews Earth & Environment". It warns of the growing pressure on nocturnal ecosystems.
Annual increase of two to ten percent
Humans and animals are under the influence of light pollution. For example, artificial light impairs the migratory and reproductive behavior of animals - "even at the low illuminance levels of diffuse skylight", the scientists write. At the same time, there are technological gaps in nighttime Earth observation, explained the Brandenburg University of Technology (THB), which was involved in the study, in a press release.
"The research revealed that almost half of the Earth's surface is affected by light pollution due to artificial lighting, with artificial light sources outshining the natural darkness by up to several thousand times," says Andreas Jechow, Professor of Fundamentals of Ophthalmic Optics and Optical Instrumentation in the Department of Engineering at THB. "These findings are based on data from satellite images and star observations, which revealed an annual increase in global light emissions of at least two percent and possibly up to ten percent."
Changes "at an alarming rate"
Artificial light is changing the night sky and nocturnal ecosystems at an alarming rate. "In urban areas, light emissions from sources such as streetlights result in zenithal radiation that is 40 times greater than that of an unpolluted night sky," the team describes in the article. More than 50 percent of the light recorded by the satellites at night occurs in non-urban areas. Sources for this include transportation networks and resource extraction.
To preserve the night sky for future generations and protect nocturnal ecosystems, more technological progress is needed in this area. Currently, the day-night band sensor of the VIIRS satellite is used most frequently. This cannot detect blue light. However, this is crucial for assessing light pollution when switching to LED technology. "This means that the true extent of the increase in light pollution is still being underestimated with satellite data," says Jechow.
Technological innovations are essential
In addition, current monitoring techniques can only carry out a limited number of measurements and lack spectral and spatial resolution. However, these are needed for a serial analysis to track the trend in light pollution.
The team also points out the impact on the environment and financial consequences: 20 percent of global electricity consumption and six percent of CO₂ emissions are caused by indoor and outdoor lighting. The scientists advocate an operational Earth observation mission for nighttime light and compare this proposal with the Landsat or Sentinel program.
The study was led by Hector Linares Arroyo from the Stars4All Foundation, with the collaboration of THB and other researchers from Spain, the USA, Canada, the Netherlands, Ireland and Germany.
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