Photo: Daniel Blaufuks
Light pollution is also harming our environment. Some 30 per cent of vertebrate species, and more than 60 per cent of invertebrates are nocturnal and many more are crepuscular (active at dusk and dawn). All are threatened by our increasing use of light at night. As an Italian scientist told me, “We have levels of light hundreds of times higher than the natural level during the night. What would happen if we modified the day and lowered the light a hundred times?” His point is that “you cannot modify light half the time without consequences.”
A few examples of these consequences include impacts to birds, sea turtles and insects. Most birds actually migrate at night, and light pollution confuses them and draws them into danger. Birds collide with lights, circle lights until they die of exhaustion, or are drawn into cities and collide with buildings. Similarly, sea turtles have evolved over hundreds of millions of years to hatch on beaches at night and to crawl toward the brightest light on the horizon.
For hundreds of millions of years, the brightest lights were the natural lights of the moon and stars over the ocean, but now the brightest lights are often the hotels and streetlights—and so the baby turtles crawl away from the ocean and to their death. Finally, lights draw insects to their deaths in huge numbers. A new light set in a previously dark area draws insects toward it, and in so doing eliminates them from the ecosystem. Because so many other species rely on insects as food, when the insects die the entire food chain is harmed. We are only beginning to understand how damaging light pollution is for the environment, but one thing is for certain: life on earth evolved with bright days and dark nights, and every living thing needs darkness for optimal health.
Why brighter is not always better
But don’t we need all this light for safety and security? In fact, while some light can help us be safer and more secure, more light does not automatically mean more safety. Unfortunately, we think it does; so we use unnecessary amounts of light at night, and we use light in ways that actually make us less safe and secure.
It’s important to understand that light is not the problem – it’s how we use it that’s the problem. Think, for example, of the way bright lights make it harder for our eyes to see at night. This can often happen when we are driving, which can increase the danger of an accident. Also, bright lights cast shadows where criminals can hide − they can see us as we walk down the street but we can’t see them in the shadows. And finally, bright light creates the illusion of safety, so that we think we are safe when actually we might not be.
No one is saying we should not have artificial light at night. But too often our use of light at night is irresponsible and wasteful. What we really need is thoughtful and intelligent lighting that helps us to see at night, rather than simply blasting light everywhere.