The Earth is ever more polluted by the artificial light

Photo: NASA
More than 80% of humanity lives under skies awash in artificial light, and a third of the population of the planet may never see the milky Way.

The Earth is more and more flooded with artificial light, a phenomenon exacerbated by the new technology of lamps, diode light emitting (LED), shows an analysis of observations of a satellite, confirming that a light pollution increasingly affects the health of humans, animals and plants.


The researchers, whose work is published Wednesday in the journal Science Advances, have determined that the lighting global has increased, both in quantity and intensity, of about 2 % per year from 2012 to 2016.


The increase of artificial light is produced almost everywhere on the globe, with regions of low informed previously where the luminescence is significantly more important, leading Christopher Kyba, a researcher at the Centre GFZ research of geophysics at Potsdam in Germany, the main author.


This study is the first to examine from space the effects of the ongoing transition in the world to LED lighting which is significantly less energy intensive.


The results indicate that the electricity savings resulting from this new technology are lower than expected.


Alarm bell


Given that the LED lamps produce the same amount of light with much less electricity, experts thought that the expenditure, particularly cities in the world devoted to the public lighting would be reduced.


But the researchers concluded that the energy savings thanks to LED technology have apparently been invested to install more outdoor lighting.


“There is a good potential for a true revolution of the lighting in order to both save energy and reduce light pollution, but only if we do not devote the savings to create even more light,” says Christopher Kyba.


In previous works, it was shown that the light emissions per head were three to four times higher in the U.s. than in Germany. This shows that it is possible to ensure the same level of prosperity and security with a use more restricted to the artificial light, argues the researcher.


But unfortunately, the judge does it, the brightness artificial will continue to increase at night in the world, with negative consequences on the environment and health.


Light at night can disrupt the circadian rhythm, the biological clock, which increases the risk of cancer, diabetes, and depression. It can also inhibit the dormancy of plants that allows them to survive the rigors of the winter.


“We hope that the results of this research will further pull the alarm as to the many consequences on the nature of the use of excessive artificial light at night “, noted Scott Feierabend, executive director of the international Association of black nights ” International Dark-Sky Association “.


Light Pollution underestimated


It points in particular to the fact that the LED lights emit lots of blue light that the instrument used in the NASA satellite for this study cannot detect.


Thus the study may have under-estimated the magnitude of the light pollution.


In addition, this light is diffused more in the earth’s atmosphere than other light sources of other colors which means that the satellite has not captured all of the intensity of the glow of cities at night that apparently were less brilliant than before the adoption of LED bulbs, ” says Christopher Kyba.


According to a new world atlas of light pollution published in 2016, more than 80 % of humanity lives under skies awash in artificial light, and a third of the population of the planet may never see the milky Way.


This card allows for the study of the artificial illumination as a pollutant with a potential impact on health and ecology, explained then the international team that developed it.


These scientists, led by Fabio Falci, a researcher of the Italian Institute of technology and the science of light pollution (ISTIL), explained that ” the light levels of the LED technology and its colours could lead to a doubling or even a tripling of the luminescence of the sky during the dark nights “.

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