Tag Archives: light pollution

LED light savings backfire spectacularly as light pollution increases dramatically

LEDs promised to bring a revolution in outdoor lighting and in a way, they did. It just might not be what we were hoping for.

Light pollution is almost ubiquitously associated with urbanization. Image credits: Wonderlane / Flickr.

When solid-state lighting options such as LEDs, OLEDs, and PLEDs were introduced, everyone hoped that they would reduce costs, energy usage, and the environmental impact of outdoor lighting. After all, these new systems consumed less and often have a longer lifespan than their conventional counterparts. But a new study has found that due to these reduced costs, many municipalities are actually using more and more lighting, creating a net effect that’s even worse than before. Not only are some places consuming more energy overall, but they are producing much more light, with potentially dramatic consequences on wildlife and our own health.

Better isn’t always better

Instead of reaping the benefits of lower costs, many municipalities recklessly took advantage of the new technology and installed more and more lighting posts, resulting in using even more energy than before.

“As a result, the world has experienced widespread ‘loss of the night,’ with half of Europe and a quarter of North America experiencing substantially modified light-dark cycles,” write the researchers in the new study, which was published today in Scientific Advances.

This growth is tightly correlated with the increase of the Gross Domestic Product (GDP), and the fastest growth occurred in developing countries. However, developed areas also tended to show an increase in light production.

“What’s more, we actually see only part of the light increase”, says Christopher Kyba whose research is done both at GFZ and the Leibniz Institute for Freshwater Ecology and Fisheries IGB.

What Kyba is alluding to is the fact researchers were expecting the measured light to go down dramatically, because the Day-Night-Band instrument which was used to gather the data doesn’t see wavelengths below 500 nanometers (human visible range is between 400 and 700 nm). LEDs output much more light below the 500 nm threshold than regular light bulbs, so even if light consumption remained the same, researchers were expecting to measure an overall luminosity, due to the measuring limitation. But they didn’t. If anything, they reported more luminosity than ever in many parts of the world.

“For that reason I expected that wealthy countries would appear to be getting darker (even if that wasn’t truly the case). Instead, we observed wealthy countries staying constant, or in many cases increasing,” Kyba told Gizmodo. “That means that even though some cities are saving energy by switching to LEDs, other places are getting brighter by installing new or brighter lamps (that need new energy). So the data aren’t consistent with the hypothesis that on the global scale, LEDs are saving energy for outdoor lighting applications.”

More light, more problems

Photograph of Calgary, Alberta, Canada, taken from the International Space Station on Nov. 27, 2015. Many areas on the outskirts are newly lit compared to 2010, and many neighborhoods have switched from orange sodium lamps to white LED lamps. Credits: NASA’s Earth Observatory/Kyba, GFZ.

Artificial light is, of course, crucial to modern society. It allows us to work at any time or in naturally dark environments and it offers possibilities for recreation and sports — it allows us to do what we want when we want it, no longer depending on the Sun’s natural cycle. However, too much light can be a bad thing, with several studies accusing it of compromising health and disrupting ecosystems.

In 2007, “shift work that involves circadian disruption” was listed as a probable carcinogen by the World Health Organization’s International Agency for Research on Cancer. Another recent study by Professor Steven Lockley at Harvard Medical School found that artificial light, even dimmed, can have significant effects on sleep disruption and melatonin suppression. Light pollution also poses a serious threat to wildlife — particularly to nocturnal wildlife. Despite all these warning signs, not much action has been taken to limit light pollution, and as urbanization spreads more and more, so too does light pollution.

Still, there are reasons to be optimistic. Unlike other types of pollution, light doesn’t require any dramatic action to reverse its effects. All you do is switch it off, and it’s gone (unlike say oil pollution, where even if you stop the pollution source, you still need to clean up the existing mess). Also, some places were less careless than others. Light emission per capita in Germany is three times lower than in the US, while the standard of living is just as much, if not significantly higher. This gives hope that prosperity doesn’t always mean going over the top with resource consumption, and a reasonable energy consumption (along with a reduction of light pollution) can be achieved — but only with responsible policies. Perhaps it’s time for such policies to emerge at a local, national, and even international level.

The study has been published in Science Advances.

Light pollution causes spring to come earlier

Our night lights may be confusing plants and in a way, making spring come earlier than it should, a new study has found.

Mexico City at night, with a brightly illuminated sky. Photo by Fernando Tomás.

We often talk about all types of pollution, but light rarely gets the spotlight. Most cities are very bright in the night, and this light can cause significant adverse effects on both human and animal bodies. However, the biggest sufferers could actually be the ones who rely on light the most: plants.

[You should know] Eight in ten Americans can’t see the Milky Way due to light pollution

If trees are exposed to light every night, then they start blooming faster, and this triggers a whole cascade of other effects. Many creatures base their lifecycles on trees.

“Our finding that the timing of bud burst of woodland tree species may be affected by light pollution suggests that smaller plants growing below the height of street lights are even more likely to be affected,” said Professor Richard ffrench-Constant of the department of the department of Biosciences based at the University’s Penryn campus. “Such results highlight the need to carry out experimental investigation into the impact of artificial night-time lighting on phenology and species interactions.”

This isn’t exactly unexpected news, but it once again shows that we don’t truly understand the effects of light pollution. Of course, switching lights off when they’re not needed is generally a good idea, but researchers also suggest that using other wavelengths could make a big difference.

Adrian Spalding of Spalding Associates in Truro is one of the leading experts on moths in Britain and he also believes that light pollution can have a massive effect on insects – both direct and indirect.

“This study shows the importance of collaborative research between business and academia to address our real concerns of the effect of lighting on plants and animals and the importance of managing light levels in our urban environment in a sustainable way.”

Journal Reference: Light pollution is associated with earlier tree budburst across the United Kingdom. .

The bright areas of the map show where stars and constellations are blocked. Credit: Falchi et al, Science Advances; Jakob Grothe/National Park Service, Matthew Price/CIRES/CU-Boulder.

Eight in ten Americans can’t see the Milky Way due to light pollution

The vibrant night’s sky that has enchanted countless generations is fading from memory. Eight in ten Americans and a third of the world live in areas where the luminous fog set by cities’ bright lights obscure the Milky Way, and even some of the brightest planets in our solar system.

Any eye-opening map

The bright areas of the map show where stars and constellations are blocked. Credit: Falchi et al, Science Advances; Jakob Grothe/National Park Service, Matthew Price/CIRES/CU-Boulder.

The bright areas of the map show where stars and constellations are blocked. Credit: Falchi et al, Science Advances; Jakob Grothe/National Park Service, Matthew Price/CIRES/CU-Boulder.

Chris Elvidge, a scientist with NOAA’s National Centers for Environmental Information in Boulder, Colorado, is a part of a team of researchers who charted the night’s sky against background light sources here on Earth. Using data like low-light imaging from the NOAA/NASA Suomi National Polar-orbiting Partnership satellite and thousands of ground observations, they were able to make a light pollution map which highlights which areas of the globe are now oblivious to the night’s sky.

“We’ve got whole generations of people in the United States who have never seen the Milky Way,” said Chris Elvidge, a scientist with NOAA’s National Centers for Environmental Information in Boulder, Colorado. “It’s a big part of our connection to the cosmos — and it’s been lost.”

The lights of a city drown out those coming from stars because they effectively make the atmosphere glow. Rays from bright city lights hit molecules in the air which reflect the light back down covering the city and its vicinities into a dome. Inside this dome, the noise is so significant that faint light sources like nebulae or distant galaxies can’t be seen anymore. Bright objects such as the Moon, the big planets, or some of the bright stars, are not affected by light pollution. You can see the different between a heavily light-polluted and low light-polluted night sky below.

Image via Stackexchange

Image via Stackexchange

The atlas suggests that countries like the United States, Singapore, North Korea or Western Europe have the most extensive light pollution. Canada and Australia retain the darkest sky, owing to the vast portions of their landmass being uninhabited. The United States also has wide patches of open spaces, but half of the country is still too bright to see the Milky Way.


“In the U.S., some of our national parks are just about the last refuge of darkness — places like Yellowstone and the desert southwest,” said co-author Dan Duriscoe of the National Park Service. “We’re lucky to have a lot of public land that provides a buffer from large cities.”

Besides missing a stellar spectacle, light pollution also affects wildlife. The unnatural light confuses insects, birds and even sea turtles and can get them killed. Light pollution is also perilous to human health because it alters our natural sleep-wake cycles or the circadian rhythm.

One obvious solution is for municipalities to use more environmentally friendly lighting. Unfortunately, the night’s sky will likely be fogged even more as cities switch to LED lights which can be ten times more energy efficient, but also give out an even white light which is the most effective at blocking the Milky Way. These LED lights can be shielded to restrict their light emissions to their immediate surrounding area, though. It costs a bit more, so notify your representatives and town officials that this is something that’s important to the community.

Findings appeared in the journal Science Advances.

Light pollution impeding rainforest regeneration: Seed dispersing bats avoid feeding in light polluted areas

When you think about pollution, usually dirty chemical substances pop to mind; maybe some petroleum, or waste water – light pollution doesn’t usually take the first places. But a new study conducted by scientists from the German Leibniz Institute for Zoo and Wildlife Research Berlin (IZW) showed that light pollution can also have a significant effect.

What is light pollution, anyway?

batsWell, as the name pretty much explains it, light pollution is excessive, misdirected, or obtrusive artificial light. It is introduced by humans directly or indirectly, and it generally occurs in or near big cities – but this is not always the case. Light pollution is basically a side-effect, a by-product if you will of human development; where humans thrive, like for example in Europe, or the US or the developed parts of Asia, we start using more and more light, until it has a negative effect.

Working with Sowell’s short-tailed bats (Carollia sowelli), Daniel Lewanzik from the IZW first built simple flight cages, and then gave the bats a simple choice. He divided the cages into two compartments: one was naturally dark and the other was illuminated by a sodium street lamp, the most common form of street lighting in the world. Inside both parts of the cage, bats were offered some of their favorite snacks: pepper plants, nightshade and figs. The results were pretty clear: bats flew into the darker compartments twice more often than in the illuminated ones.

In a second experiment, Lewanzik illuminated pepper plants growing in the wild with a street light and measured the percentage of ripe fruit which bats harvested from plants in a dark location and from lit plants. Naturally, 100 percent of the naturally dark plants were harvested – it’s not like bats to give up on a tasty meal. However, only three quarters of the illuminated plants were harvested, which shows that even when offered the possibility of a feast, they sometimes still turn it down, if there’s light involved. Although insect-eating bats have been shown to avoid foraging in light-polluted areas, this is the first study to show that fruit-eating bats also avoid areas with light – and this is significantly more important, because bats play a key role in pollinating plants and spreading their seeds, especially the seeds of species that are first to recolonise cleared land.

“In tropical habitats bat-mediated seed dispersal is necessary for the rapid succession of deforested land because few other animals than bats disperse seeds into open habitats”, says Daniel Lewanzik, doctoral candidate at the IZW and first author of the study.

Basically, bats eat fruits and then defecate while flying, spreading the seeds all around. This is a very natural process, and it helps plants regenerate. If they avoid some areas, then those areas will regenerate considerably slower.

If we want to prevent this, there are some things we can do:

“The impact of light pollution could be reduced by changes in lighting design and by setting up dark refuges connected by dark corridors for light-sensitive species like bats,” Lewanzik says.

Full bibliographic informationLewanzik D, Voigt CC (2014): Artificial light puts ecosystem services of frugivorous bats at risk. Journal of Applied Ecology.