The future looks bright: light pollution rises on a global scale

WASHINGTON (Reuters) - The world is getting brighter, but scientists say that may not be a good thing.

Researchers said on Wednesday satellite data showed that Earth's artificially lit outdoor surface at night grew by about 2 percent annually in brightness and area from 2012 to 2016, underscoring concerns about the ecological effects of light pollution on people and animals.

The rate of growth observed in developing countries was much faster than in already brightly lit rich countries.

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Satellite images of Earth at night
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Satellite images of Earth at night
Earth's airglow is seen with an oblique view of the Mediterranean Sea area, including the Nile River with its delta and the Sinai Peninsula, in this October 15, 2011 NASA handout photograph taken by a crew member of Expedition 29 aboard the International Space Station. Some areas of the photo like the river and river delta appear as the brightest areas because of either man-made lighting (mostly incandescent) or man-made lighting reflected off nearby surfaces. The other areas appear to be illuminated naturally by moonlight, starlight, or back-scattered light from the atmosphere, according to NASA. Picture taken October 15, 2011. REUTERS/NASA/Handout (UNITED STATES - Tags: SCIENCE TECHNOLOGY) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS
A composite image released by NASA on April 12, 2017 showing the full western hemisphere at night. The principal challenge in nighttime satellite imaging is accounting for the phases of the moon, which constantly varies the amount of light shining on Earth, though in predictable ways. Likewise, seasonal vegetation, clouds, aerosols, snow and ice cover, and even faint atmospheric emissions (such as airglow and auroras) change the way light is observed in different parts of the world. This map of night lights is based on imagery from 2016. NASA Earth Observatory image by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Rom?n, NASA's Goddard Space Flight Center/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY
NASA satellite image shows the United States, Mexico and Canada at night in this composite assembled from data acquired by the Suomi NPP satellite in April and October 2012. The image was made possible by the new satellite's "day-night band" of the Visible Infrared Imaging Radiometer Suite (VIIRS), which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires, and reflected moonlight. REUTERS/NASA/Robert Simmon/NOAA/Department of Defense/Handout (UNITED STATES - Tags: ENVIRONMENT SCIENCE TECHNOLOGY TPX IMAGES OF THE DAY) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS
A NASA Earth Observatory image released December 5, 2012 shows Britain, Ireland and part of Western Europe as it appeared on the night of March 27, 2012. The image was acquired by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite. The image is based on data collected by the VIIRS "day-night band," which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe signals such as gas flares, auroras, wildfires, city lights, and reflected moonlight. REUTERS/NASA Earth Observatory/Handout (SCIENCE TECHNOLOGY ENVIRONMENT TPX IMAGES OF THE DAY) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS
North Korea (the dark area) and South Korea at night are seen in an undated NASA handout picture from the International Space Station. The clarity of the night image is possible thanks to the European Space Agency's NightPod, installed on the station in 2012, according to a NASA news release. It incorporates a motorized tripod that compensates for the station's speed of approximately 17,500 mph and the motion of the Earth below. REUTERS/ NASA/Handout via Reuters (OUTER SPACE - Tags: SCIENCE TECHNOLOGY) ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS
A NASA handout released December 5, 2012 of a composite image of Asia and Australia at night, assembled from data acquired by the Suomi NPP satellite in April and October 2012. The image was made possible by the satellite's "day-night band" of the Visible Infrared Imaging Radiometer Suite (VIIRS), which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires and reflected moonlight. REUTERS/NASA Earth Observatory/Handout (SCIENCE TECHNOLOGY ENVIRONMENT) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS
The locations of permanent lights in North America are seen in this October 23, 2000 handout image from NASA. This image of Earth?s city lights was created with data from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) which was originally designed to view clouds by moonlight. The brightest areas of the Earth are the most urbanized, but not necessarily the most populated. REUTERS/NASA/Handout. EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS.
***CAPTION CORRECTION*** UNITED ARAB EMIRATES - 19 SEPTEMBER 2016: Abu Dhabi, Dubai and Al Ain are illuminated from space by building and street lights in United Arab Emirates, 19 September 2016. Gaze down at the Earths sprawling surface from the International Space Station. Throughout 2016 astronauts aboard the ISS have been documenting the ever-changing face of the Earth, capturing vast deserts, isolated mountain regions and bustling cities. The grand space station orbits the Earth at an altitude of 205 and 270 miles, and goes round the planet an incredible 15.5 times each day. Even though Earth has a 40,075km circumference, each orbit of the earth only takes 92.65 minutes in the ISS. PHOTOGRAPH BY NASA /SPL / Barcroft Images London-T:+44 207 033 1031 E:hello@barcroftmedia.com - New York-T:+1 212 796 2458 E:hello@barcroftusa.com - New Delhi-T:+91 11 4053 2429 E:hello@barcroftindia.com www.barcroftmedia.com (Photo credit should read NASA / SPL / Barcroft Images / Barcroft Media via Getty Images)
***CAPTION CORRECTION*** NILE RIVER - 5 DECEMBER 2016: The Nile river is illuminated by city street lights and buildings, making it visible from the International Space Station in Nile River, 5 December 2016. Gaze down at the Earths sprawling surface from the International Space Station. Throughout 2016 astronauts aboard the ISS have been documenting the ever-changing face of the Earth, capturing vast deserts, isolated mountain regions and bustling cities. The grand space station orbits the Earth at an altitude of 205 and 270 miles, and goes round the planet an incredible 15.5 times each day. Even though Earth has a 40,075km circumference, each orbit of the earth only takes 92.65 minutes in the ISS. PHOTOGRAPH BY NASA /SPL / Barcroft Images London-T:+44 207 033 1031 E:hello@barcroftmedia.com - New York-T:+1 212 796 2458 E:hello@barcroftusa.com - New Delhi-T:+91 11 4053 2429 E:hello@barcroftindia.com www.barcroftmedia.com (Photo credit should read NASA / SPL / Barcroft Images / Barcroft Media via Getty Images)
SPACE - FEBRUARY 6: The Atlantic coast of the United States taken at night from the International Space Station on February 6, 2012 in Space. An Expedition 30 crew member aboard the International Space Station took this night time photograph of much of the Atlantic coast of the United States. Large metropolitan areas and other easily recognizable sites from the Virginia/Maryland/Washington, D.C. area are visible in the image that spans almost to Rhode Island. Boston is just out of frame at right. Long Island and the New York City area are visible in the lower right quadrant. Philadelphia and Pittsburgh are near the center. Parts of two Russian vehicles parked at the orbital outpost are seen in left foreground. PHOTOGRAPH BY NASA / Barcroft Media /Barcoft Media via Getty Images
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The researchers said the U.S. National Oceanic and Atmospheric Administration weather satellite data may understate the situation because its sensor cannot detect some of the LED lighting that is becoming more widespread, specifically blue light.

"Earth's night is getting brighter. And I actually didn't expect it to be so uniformly true that so many countries would be getting brighter," said physicist Christopher Kyba of the GFZ German Research Centre for Geosciences, who led the research published in the journal Science Advances.

With few exceptions, growth in nighttime light was observed throughout South America, Africa and Asia. Light remained stable in only a few countries. These included some of the world's brightest such as Italy, Netherlands, Spain and the United States, although the researchers said the satellite sensor's "blindness" to some LED light may mask an actual increase.

Australia's lit area decreased due to wildfires. Nighttime light declined in war-hit Syrian and Yemen.

Ecologist Franz Hölker of Germany's Leibniz-Institute for Freshwater Ecology and Inland Fisheries (IGB) said light pollution has ecological consequences, with natural light cycles disrupted by artificial light introduced into the nighttime environment. Increased sky glow can affect human sleep, he noted.

"In addition to threatening 30 percent of vertebrates that are nocturnal and over 60 percent of invertebrates that are nocturnal, artificial light also affects plants and microorganisms," Hölker said. "It threatens biodiversity through changed night habits, such as reproduction or migration patterns, of many different species: insects, amphibians, fish, birds, bats and other animals."

Kyba said nighttime lighting also obscures the stars that people have witnessed for millennia.

Experts had hoped the growing use of highly efficient LED lighting might lessen energy usage worldwide. The new findings indicate use of artificial lighting instead is growing, increasing energy demand.

"While we know that LEDs save energy in specific projects, for example when a city transitions all of its street lighting from sodium lamps to LED, when we look at our data and we look at the national and the global level, it indicates that these savings are being offset by either new or brighter lights in other places," Kyba said.

(Reporting by Will Dunham; Editing by Sandra Maler)

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