D r K e l l i e P e n d o l e y
Director & Principal Scientist, Pendoley Environmental
Humans love bright light at night, it lets us work, play and have fun after the sun has set. However, this light can also be considered a pollutant when it is used to excess, or in places or at times when it is not wanted or needed. All over the world light pollution is increasing every year and is causing problems for humans and wildlife. Light pollution, sometimes called Artificial Light at Night (shortened to ALAN), can disrupt the natural night and day cycles in humans and wildlife and prevents us from seeing the stars overhead. Almost all life on earth has evolved over millions of years to follow daily cycles of darkness and sunlight, and seasonal cycles of long days in summer and short days in winter. With the invention of the electric light these natural cycles have let humans extend the day length at any time we wish.
Of all the animals on our planet, perhaps none are under more threat from light pollution than sea turtles. Sea turtles live in the ocean, but they lay their eggs at night on sandy beaches. After a few months the eggs hatch, usually at night, and to avoid being eaten by birds or crabs, hatchling sea turtles must find the ocean as soon as they leave the nest. Hatchlings have evolved to locate the ocean by crawling toward the brighter horizon caused by starlight and moonlight reflected off the sea surface and by crawling away from tall dark landward silhouettes of dunes and vegetation. Finding a dark beach to lay eggs on is getting harder for female turtles because of the increasing light pollution from cities, ports and industry. When hatchlings emerge from their nest on light polluted beaches they are confused and cannot find the ocean easily. Instead of reaching the safety of the ocean, the newborn sea turtles often crawl towards streetlights, or lighting from houses, shops, marinas, ports, campgrounds, hotels and even campfires on the beach, leading to danger and death. All over the world thousands of hatchling sea turtles die this way every year.
Turtles are not the only species affected by ALAN. Young shearwater birds learning to fly for the first time can crash into street lights when they confuse them with the moon, Tamar wallabies can have babies at the wrong time of year when there is not enough food for them to grow, and mountain pygmy possums can starve when the bogong moths they rely on for food are attracted to light and do not reach the possum habitat where they can catch and eat them. Humans are also affected by ALAN, lights from computer and phone screens can keep us awake late at night which causes many health problems associated with not being able to sleep well, including obesity, anxiety, depression, heart disease and cancer. Finally, ALAN also stops us from seeing the stars in the sky at night. In North America and Europe more than 80% of the people cannot see the Milky Way and Astronomers can no longer use their telescopes.
Luckily it is easy to stop these impacts from happening, it is as easy as switching lights off. Switching of the lights protects the night sky from light pollution which will protect human health and well-being, protect wildlife and habitat, and allows humans to see the stars as they have done for thousands of years. Volunteer organisations all over the world are working to tell people about light pollution and how to stop it and in Australia, the Australasian Dark-Sky Association (ADSA) can provide tools you can use to protect night skies for sea turtles and all wildlife.
There are five simple rules
for reducing your
Start with natural darkness and only add light if it is needed.
Use controls such as dimmers, motion sensors and timers to stop lights shining all night if they are not needed.
Use the lowest intensity lighting that you need, it is surprising how little light humans need to see properly at night.
Only light the area or object you want lit, make sure the light is shielded from above, directed onto the object to be illuminated and does not shine wastefully into the sky or onto a neighbour.
Use light with little or no blue light (orange and red lights are always better than white lights).