Light pollution sparks community action

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“Can you see the star sequence or Milky Way?” Community answers to simple questions like this are helping researchers combat light pollution.

Rapid urbanization, growing use of energy-saving light-emitting diode (LED) for street lighting and limitations of scientific instruments to accurately measure light pollution have forced researchers to seek community participation to collect data.

Recent studies have confirmed that the growing use of LED lights has increased light pollution to the extent that 36 percent of the world’s population could not see the Milky Way from their home in 2014, including 60 percent of Europeans and 78 percent of the US population.

Christopher Kyba from the GFZ German Research Centre for Geosciences in a study published in Nature Astronomy on Friday reveals that as cities change their street lighting from orange sodium vapor lamps to white LEDs, the color of the night sky also varies.

“This can fool many existing instruments into thinking that areas are getting darker when a human would actually say it got brighter,” Kyba told CGTN.

Apps, organizations collect data from stargazers

Researchers have launched several apps like “The Globe at Night” project that started in 2006 and produced the most extensive dataset about the dark sky. The app asks participants to evaluate a series of eight stars they can see with the naked eye.

One app “The Loss of the Night” designed to complement The Globe at Night, asks participants to draw the sequence of individual stars and report their visibility. “The accuracy of the observation can be evaluated by checking whether the decisions are self-consistent. Experienced participants can make precise observations” Kyba said.

Apart from apps, organizations such as the International Dark-Sky Association (IDA) are helping reduce skyglow through community awareness and policy advocacy.

IDA and China are limiting light pollution

China's Dark Sky Park is located in the core areas of Ngari's Dark Sky Reserve. /Xiaohua Wang Photo

Last year, the China Biodiversity Conservation and Green Development Foundation (CBCGDF) started a project to create a dark sky reserve in a bid to preserve the visibility of starry nights. The initiative is aimed at curbing light pollution while also raising awareness about it.

The reserve spreads over 2,500 square kilometers in area at Ngari, southwest China's Tibet Autonomous Region, which borders India and Nepal.

There are only 12 dark sky reserves that have been accredited by the International Dark-Sky Association.

They include Aoraki Mackenzie (New Zealand), Brecon Beacons National Park (Wales), Central Idaho (US), Exmoor National Park (England), Kerry (Ireland), Mont-Mégantic (Québec), Moore's Reserve (England), NamibRand Nature Reserve (Namibia), Pic du Midi (France), Rhön (Germany), Snowdonia National Park (Wales) and Westhavelland (Germany).

Kyba’s previous study had revealed China light pollution as the global average. Despite the massive growth of Chinese cities, the country managed to contain its annual increase in the area lit artificially below 2.1 percent and its brightness below 1.9 percent.

The fastest growth in night light is happening in developing regions of Asia, Africa, and South America. On the contrary, illumination in brightly lit the US, the Netherlands, Spain, and Italy has stabilized.

Researchers suggest communities report cases of light pollution to create a database that can complement scientific findings on the issue.

“The advantage of human observations is that they by definition correctly take into account the changing color of the sky," Kyba said.