Credit: P. Cinzano, F. Falchi (University of Padova), C. D. Elvidge (NOAA National Geophysical Data Center, Boulder). Copyright Royal Astronomical Society.
Dark nights: the global effort to tackle light pollution
31st August, 2010
The energy, financial and health costs of lighting up our homes and streets could be saved through better lighting and an end to wasteful illuminations
Darkness reigned at night until 200 years ago, when English inventors discovered how to make electrified carbon glow. The invention of the light bulb loosened the grip of darkness, gradually illuminating our world after sundown.
Now, bright billboards, stadiums, parking lots, roadways and buildings cast a collective glow into our atmosphere, and offer enough ambient light to make land visible from space at night.
But with all of our modern technology allowing us brighter evenings, we pay a price: artificially lightened nights change our environment in many ways, including disrupted ecological dynamics and an obscured landscape.
Living in around-the-clock light can harm our health, too: scientists are associating artificial illumination at night with breast cancer. Diminishing dark skies also means cultural loss - constellations are a part of our heritage, and astronomers depend on darkened skies to study our universe.
In a practical sense, light pollution wastes energy - and fossil fuels - as well as money, including taxpayers' money.
Like global warming, light pollution extends to the far reaches of the globe and affects us all. And, as with our attempts to slow climate change, uniform efforts to illuminate more wisely are a gargantuan undertaking, and one of low priority in many regions. Still, scientists and advocates around the world are wising-up to light pollution and figuring out how to solve this global quandary. With a problem as amorphous as light pollution, can our global village find a way to protect dark skies?
How light is wasted
Satellite maps of the world at night reveal continents outlined in white, with clearly defined, glaring metropolises. Much of Europe, the eastern US and eastern Asia appear thick with lights.
'What you’re seeing is light directed upwards, which is foolish because the whole point of light is to help us get around,' says Peter Strasser technical director at the International Dark-Sky Association (IDA), the largest international non-profit that keeps tabs on light intensity. In contrast, wide swathes of Africa and Australia emit nearly no light.
From ground level, city streets are often bright enough for newspapers to be read after midnight. But in regions such as Yellowstone National Park in Wyoming, night brings a rare pitch darkness; lift your eyes and that darkness makes for optimal stargazing.
Most live in darkness
Some two-thirds of the global population and 99 percent of the continental US and European Union live in areas where the night sky is considered polluted by light, according to a 2001 study by Italian astronomist Pierantonio Cinzano of the University of Padova, in his world atlas of sea-level artificial night-sky brightness.
Much like urban river pollution, light pollution’s sources are hard to pinpoint. In a classic tragedy-of-the-commons, millions of light bulbs contribute to a region’s atmospheric aura.
We light up roads and walkways at night to make our living spaces safer and to advertise our businesses. But too much light escapes to the sky, say dark-sky advocates. The worst culprits are poorly directed and poorly designed streetlights, such as the antique-style acorn lights that direct more light upward than downward.
'It makes no sense to light up the undersides of airplanes when you’re trying to light up the street,' says Strasser. Other problem sources are powerful security and stadiums lights, floodlights that illuminate historic buildings and the far-reaching lights of shopping centers.
In addition to wasted light, squandered energy costs us millions. In the US alone, some $1.7 billion is wasted each year by unnecessary, excessive and poorly designed lighting, according to the IDA. Powering wasted light releases 38 million tons of carbon dioxide into the atmosphere each year.
The damage of artificial light
Scientists who study light pollution say that in addition to wasting resources, excess artificial light harms wildlife - and us.
Living things have evolved to take cues from light. Most famously, beachside lights attract newly hatched sea turtles - which by nature travel towards the moon over the water - to our inland human illuminations.
|The International Dark Sky Association wants to name 200 dark-sky places by 2020|
Likewise, bright building lights disorient migrating birds, which then crash into the sides of buildings. The toll is in the millions, but may be closer to one billion bird mortalities each year by collision with buildings in the US alone, according to a 2006 paper by Dr Daniel Klem of Muhlenberg College in Pennsylvania, whose research on the subject spans four decades.
Brighter nights alter ecosystems in ways we’re still learning about, too. Light pollution in urban areas reduces algal consumption by zooplankton at night, because zooplankton need darkness to move about and consume surface algae, according to a study by Marianne Moore, associate professor at Wellesley College in Massachusetts. This suppression could contribute to algae blooms, known to worsen water quality.
Breast cancer links
The hazy glow of light pollution harms humans too, by disrupting our circadian systems. 'That’s how we evolved: by light and dark,' says Dr Richard Stevens, a professor and cancer epidemiologist at the University of Connecticut Health Center. 'We are designed for 12 hours of dark and 12 hours of light.'
Our ancestors used fire, and then gas lights, which only produced dim light that would be extinguished by bedtime. Now, Stevens says, many of us are living in light throughout the night.
Our bodies produce a hormone in total darkness, melatonin, which helps to regulate the immune system and fight disease. In 2009, Stevens led an ecological study in Israel that revealed a strong correlation between nighttime light levels and incidences of breast cancer. Women living in the brightest areas (defined by the ability to read outdoors at midnight) had a 73 per cent higher risk of developing breast cancer than those living in the darkest areas.
In 2010, Stevens conducted a study that looked at 164 countries and found similar results. Light affects the circadian system through the retina, not the skin, says Stevens, so blind women and women who sleep for a long time seem to be at lower risk.
Psychologically, intrusive lighting can cause poor sleep and annoyance. Light pollution also alters our dark-sky heritage on a global scale, to the point that many urban dwellers have never seen the Milky Way. Even suburban and rural areas are losing starry nights.
The Campaign to Protect Rural England argues that a pitch-dark night filled with stars is among the values that makes the countryside unique from urban areas. Unfortunately, rural England’s view of the star-filled sky is fading.
Finding dark-sky places
It wasn’t until the 1950s, after World War II, that lighting became a sign of prosperity and progress. That’s when uniform streetlights became widespread, bolstering the rise of light pollution.
Now, scientists and advocate groups are figuring out how to rein in our light obsession. Last November, the IDA honored two European parks for world-class stargazing: Galloway Forest Park in southwestern Scotland and Zselic Landscape Protection Area in southwestern Hungary. Two American communities also earned accolades for their darkened skies: Flagstaff, Arizona and Borrego Springs, California. The IDA hopes to recognise some 200 dark-sky places by 2020.
Other dark-sky groups around the globe are finding strength in numbers. In 2007, the Starlight Initiative - consisting of hundreds of scientists, non-governmental organisations, astronomers, councils and more - met in the Canary Islands, Spain, to draft a declaration stating the need to protect the darkness of the night sky as part of our shared global environment.
This year, the 3rd International Symposium for Dark-Sky Parks is being held in mid-September in Croatia.
Ways of cutting light waste
Groups that advocate for greater light control emphasise that they are not against outdoor lighting, but instead support smart, efficient lighting. Builders, engineers, highway administrators, corporations and governments will have to reduce wattages and rethink their approach to outdoor lighting. And since lighting is largely unregulated throughout most of the world, regional lawmakers could institute ordinances that outdate wasteful illuminations and require reasonable lighting.
A few laws are already in effect: In 2000, the Lombardy region of Italy passed a law that new light installations must not direct light above the horizontal. The Czech Republic enacted light pollution laws in 2002 to define light pollution and obligate Czech citizens and organisations to take light-pollution prevention measures.
Slovenia also has serious light pollution legislation, according to Andrej Mohar of Dark-Sky Slovenia. 'We had an eight per cent increase [in light pollution] in the last 15 years,' says Mohar. 'Three years after adoption of our legislation, we can measure 20 per cent less light pollution around Ljubljana, the capital.'
Rising crime fears
Talk of dimming our light pollution makes some uneasy, since we rely on artificial light at night. 'People are protective of light due to safety concerns and fear of crime,' says Emma Marrington, rural policy campaigner for the Campaign to Protect Rural England, so sometimes the mention of reducing light can raise criticism.
A guide by the New York State Energy Research and Development Authority states that 'it is clear that reductions in crime can be achieved by improvements in street lighting'.
However, 'there is a point of diminishing return - you can make a place too bright and if there’s a glare then that makes it more difficult for people to see,' says Debra Cohen of Community Oriented Policing Services, an office of the US Department of Justice.
An improperly lit home can actually aid criminals: bright lights create sharp, contrasting shadows or glare where intruders can hide. Lighting can also help criminals see what they are doing and spotlight potential targets or escape routes. Illuminated areas can also attract social activity, especially among young people, creating opportunity for crime.
Dark-sky advocates say that smarter lighting practices will diminish light pollution and increase safety: outdoor security lights should operate on motion sensors at a lower wattage, and only illuminate areas that need to be lit.
Streetlights should be shielded to diffuse glare from the bulb and should only cast light downwards. Signs and advertisements should be lit from the top down rather than bottom up. Stadium and sports lights should be directed down, not up or out. For little-used walkways, short lights with red bulbs can shed light on paths; once eyes adjust to the dark, seeing is easy.
Says Marrington: 'We believe that this problem [light pollution] can be solved with the right amount and type of lighting, where it is needed and when it is needed.'
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