An international team of researchers has presented a global map that details the impact of light pollution. One-third of world inhabitants are not currently able to view the Milky Way, due to city lights, including 60 percent of Europeans and 80 percent of Americans.

Cities should find new ways to reduce the incidence of light on the environment since bright skies may affect nocturnal organisms and their ecosystems. The “New World Atlas of Artificial Night Sky Brightness” was published on Friday in the Journal Science Advances.

World inhabitants can't see the Milky Way
A new global map named New World Atlas of Artificial Night Sky Brightness, shows that one-third of the world’s inhabitants are not currently able to view the Milky Way due to air pollution. Credit:

A team led by Fabio Falchi, researcher at the Italian Light Pollution Science and Technology Institute (ISTIL), found that four out of five people on Earth live in places where light considerably pollutes the sky.

At least one-third of the world’s inhabitants are not able to see the Milky Way, even when nights appear to be clear. The new atlas shows that a transition to LED technology is having a major effect on cities. If lighting levels are not revised, we will face a “3 fold increase in skyglow.”

“Light pollution is a global issue, and humanity has enveloped our planet in a luminous fog that prevents most of Earth’s population from having the opportunity to observe our galaxy. This has a consequent potential impact on culture that is of unprecedented magnitude,” said study authors.

Most of the world is affected by light pollution

255 million people in the United States cannot enjoy the Milky Way view. According to researchers, an estimated 99 percent of European and U.S. populations live under light-polluted skies. 

“This is a huge cultural loss with unforeseeable consequences in the future generations,” added Falchi.

Chad, Central African Republic, and Madagascar are the countries where the sky looks cleaner in the world. On the other hand, Singapore is the country most affected by light pollution. The eyes of inhabitants in the island city-state “cannot fully dark-adapt to night vision,” said the study.

More than half of inhabitants in the following countries live under “extremely bright skies,” including Kuwait (98 percent of people), Qatar (97 percent), United Arab Emirates (93 percent), Saudi Arabia (83 percent), Israel (61 percent), Argentina (58 percent).

When considering the G20 countries, Italy and South Korea are the countries most affected by light pollution, while Canada and Australia are the least. Data from cities was obtained by the American Suomi NPP satellite, said researchers in a press release issued on Friday.

A world atlas featuring levels of night-sky brightness had been published in early 2000s. The new updated map includes data from advanced tools. Citizen scientists have provided 20 percent of all data used to calibrate the atlas in countries outside North America and Europe.

Light pollution might interfere with astronomical observations

High levels of brightness caused by night lights may affect astronomical observations. According to Chris Elvidge, co-author and physical scientist for NOAA, the view gets scattered as “light hit molecules and particles in the atmosphere,” as reported by the Washington post.

Light pollution might also bring consequences in the fields of ecology, health, and energy added researchers in the Study. They propose that effects of this phenomenon cannot be reversed, so it is important to take action now.

Which are the solutions to reduce light pollution?

Researchers mentioned that there were available techniques to reduce light brightness in cities. Some countries have already implemented them, including Lombardia, Italy, Slovenia and two regions in Chile.

The optimum solution to lower the impact of light pollution would be to shield of luminaires, to only send light where is necessary, reduce light levels substantially in some areas, and limit the use of blue light, which has a major effect on circadian rhythms.

“Perhaps the current generation will be the final generation to experience such a light-polluted world, as light pollution is successfully controlled. Alternatively, perhaps the world will continue to brighten, with nearly the entire population never experiencing a view of the stars,” concluded the authors.

Adaptive lighting may also play a significant role to reduce night brightness. For instance, street lights can be set to adapt, depending on meteorological conditions, or to turn automatically off when no cars are passing.

Autonomous vehicles would collaborate in the change since they would not depend on street lights. Authors have criticized theories that relate increases in artificial light with decreases in street crime.

“This belief is not based on scientific evidence,” they added.

The new atlas has been described as a benchmark for governments, which want to evaluate if measures they apply to prevent light pollution are effective or not. Authors remarked that such a problem might be hard to solve, given that worldwide populations are increasing.

Light pollution expert Paul Bogard told that it is not always true that light is better. He mentioned that kids in the United States and Europe “have no idea what they are missing” and some of them would never be able to see the Milky Way.

Here is a video from the NASA’s Hubble Space Telescope featuring the center of the Milky Way:

Source: Science Advances