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The twinkling stars and the moon in the sky have mesmerised humans for ages. Star-studded skies have inspired generations of art, science and poetry. However, today, most of us live under pale, starless, light-polluted skies, unable to experience the scale of the universe and the perspective it provides. The rampant increase in artificial lighting has changed the way we see skies.
Light pollution and the usage of excessive lighting are growing environmental concerns. A study conducted in 2016 by Fabio Falchi, Christopher Kyba and other scientists found that more than 80% of the world's population lives under light-polluted skies, and light pollution can cause global ecological consequences.
Ecological concerns
Light pollution is excessive lighting that goes where it is not supposed to. It can cause a glow in the sky, washing away the stars. Its effects on the environment are far-reaching, but not spoken about much, especially in India. Life on earth depends on light-dark cycles. Night-time lighting disrupts circadian rhythm and causes lasting impacts on many flora and fauna.
The 13th Convention on Migratory Species in Gandhinagar, Gujarat, in 2020 noted “that artificial light is increasing globally by at least 2% per year” and “that there are many documented instances of the negative effect of artificial light on migratory species, including avoidance by marine turtles of nesting on beaches that are artificially lit, migratory shorebirds using less preferable roost sites to avoid lights, and disruption in foraging and fledgling for a number of seabirds”.
A 2014 study by the Wildlife Institute of India found that Olive Ridley sea turtle hatchlings in Odisha were disoriented by coastal lights on their way to the sea. Another study in 2015 by the scientists at Max Planck Institute for Ornithology in Germany showed that some songbirds started singing earlier in the presence of artificial lighting.
Fireflies are one of the most magical creatures on Earth. They glow in the dark to communicate, especially to find a mate. Fireflies depend on darkness to flaunt their flashes to find potential mates. Scientists have noted a global decline in firefly populations.
A study done by a Tufts University-led team published in 2020 regarded light pollution, habitat loss and pesticide use as the most serious threats. Artificial lights also interfere with the pollination patterns of plants and the feeding habits of nocturnal animals, leading to a decline in their population.
Light pollution also affects the ecosystem's ability to regulate the balance of species. For example, it can alter the natural predation patterns of nocturnal predators and prey, leading to imbalances in the ecosystem.
Striking a balance
Exposure to lighting at night puts our biological clock off. Artificial lighting suppresses the secretion of melatonin, the hormone that regulates our sleep-wake cycle. In India, where sleep deprivation is a major public health problem, the increase in light pollution is contributing to sleep disorders, stress and other health problems. Light pollution can also cause visual discomfort and glare, making it difficult for drivers to see the road and increasing the risk of accidents.
There are ways to light our spaces in a more environment-friendly manner. By shielding the lights, directing them to the intended area, using yellow, oranger lights and motion-activated lighting, and using only what’s required only when it is required and in the amount necessary, impacts of lighting on our environment can be minimised.
With the advancements in LED lighting technology, the colour temperature can be adjusted to reduce the intensity as needed. The American Medical Association recommends using street lighting with 2700 Kelvin or below. In 2018, the city of San Francisco retrofitted all their street lights to use LEDs that are shielded and of 2700 Kelvin colour temperature. Phoenix in Arizona did the same in 2016.
The ability to adjust the colour of the lighting has benefits for some wildlife. In Florida, studies show that sea turtles are not affected by the use of long wavelength lights (560 nm or greater — amber, orange, or red). The Sea Turtle Conservancy in Florida has been retrofitting bright lights with sea turtle-friendly lights and found that disorientations drop to zero with the retrofits. In the USA's Hawaiian island of Kauai, the usage of green lights has reduced problems for Newell's Shearwater (a seabird).
There are very few accessible dark sky locations in India. Most dark places exist within protected nature reserves with wildlife movement at night. The Ladakh government recently announced India’s first night sky sanctuary to promote astro-tourism. Such reserves, in order to be sustainable, must have best practices in place.
City lights
Light pollution in cities can be reduced by planning for dark sky-friendly lighting. Streetlights are the major source of light pollution. Shielding the lights, using lights with a colour temperature of 3000 Kelvin or below and reducing the intensity after midnight, installing motion sensors etc can help.
Many cities in the US have retrofitted their street lights to the guidelines set out by the International Dark Sky Association. Lighting laws need to be put in place to regulate levels of allowed lighting in billboards and other large lighting fixtures.
Light pollution is an easier environmental concern to solve. Every one of us can play a role in preserving darkness by only using what’s required and turning it off when not necessary.
(The author is a dark sky advocate, a member of the IUCN Species Survival Commission - Fireflies Specialist Group and a co-founder of Wild and Dark Earth)