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The Challenge of Light Pollution

By David Barrie, 18th December 2023

Our continuing failure to treat the natural world with sufficient respect is causing problems which grow more terrifying every day.

Understandably, climate change and the physical destruction of entire ecosystems attract most of our attention.

But we face another environmental threat – one which is insidious and fast-growing, yet still widely ignored.

Light pollution[1].

The world we inhabit was, until modern times, governed by strict astronomical rules. Day followed night, and night was dark – except when the moon was full. This celestial regime shaped the behaviour and biological rhythms of almost every living thing.

The coming of electric light changed everything. In many places true darkness now never comes. And while we may welcome that change because some of our deepest fears are associated with the dark, all that new light is causing immense environmental harm.

There is overwhelming evidence of the destructive effects of artificial light on the animals (and plants) with which we share the planet.

A bright outdoor light is on in the dark evening and you can see all the little bugs that are attracted to the light and flying around it.
Example of light pollution. Credit: CC BY-NC-SA 2.0

To give just a few examples, it is estimated that billions – yes, billions – of migratory birds die when they are drawn to brightly lit buildings. And even that number is dwarfed by the number of insects that suffer a similar fate. Then there are the thousands of doomed turtle hatchlings that are lured away from the sea by artificial light[2].

Light pollution is a significant factor in the massive problem of biodiversity loss.

Moreover, it is increasingly clear that by banishing darkness we are also damaging our own health and well-being. Exposure to artificial light at night is associated with a host of physical and mental disorders including diabetes, depression and breast cancer.[3]

We are suffering other, less tangible losses too. The darkness that once permitted everyone on the planet to see thousands of stars, as well as the glowing ribbon of the Milky Way – our home galaxy – has been obscured by the halo of artificial light that surrounds our towns and cities. The arrival of the LED has only made matters worse. Most people living today will never see the night sky in all its glory.

The facts are not in dispute.  In some countries (France, for example) governments are already taking practical steps to address the problems of light pollution. But our own government rejected an amendment to the recent Environment Act that would have added the reduction of light pollution as target.

A recent report jointly commissioned by the Lund Trust and the Pilgrim Trust (you can find it here) highlighted some of the main reasons for the lack of progress here in the UK.

Example of light pollution. Credit: CC BY-SA 2.0.

Low public awareness is a major factor, coupled with the common assumption that more light must be better, and a widely held (but questionable) belief that it always improves our security.

Few people realise that the worst effects of light pollution can be reduced or eliminated by taking a few simple, inexpensive steps, such as installing lights with warmer colours, shielding them so that light does not spill into the sky, or using motion sensors so that they only come on when needed.

The best solution of all – just turning unnecessary lights off – has the great additional benefit of saving both energy and money. Often it is enough to draw someone’s attention to the problems. I recently persuaded the Army to remove some extremely bright lights from a base in the middle of Chichester Harbour (an AONB and an SSSI) by having a conversation with the officer in charge.

The CPRE’s annual star count is helping people to become more aware of the problem of ‘skyglow’, and it’s good news that several Dark Sky Parks have been designated in the UK. Buglife (with the support of the Pilgrim Trust) lobbied for changes to the Environment Act.

But, while many charities take an interest in light pollution, few treat it as a priority, and, because their efforts are fragmented, progress in tackling it has been painfully slow. Even funders that call for high standards of environmental sustainability often overlook the need to reduce light pollution.

Much more needs to be done.

A bright street light is on in the dark evening and you can see all the little bugs that are attracted to the light and flying around it.
Example of light pollution. Credit: CC BY 2.0

So here are a few ideas:

  • Why don’t all grant-making environmental charities devise and adopt a code of conduct in relation to light pollution?
  • Why don’t these charities ask grant recipients to follow a similar code of conduct? Perhaps they could offer extra funding for this purpose.
  • A good way of raising public awareness would be to establish an annual prize in recognition of outstanding achievements in tacking light pollution. Who would like to take this on?
  • Above all, policy change is needed. Will one of our leading environmental charities launch a campaign to get the government to regulate light pollution?

Yes, it’s a big challenge, but it’s also an urgent one.

I very much hope that the funders who receive this bulletin will agree that the challenge of light pollution urgently needs to be addressed.  A meeting to discuss the options would be a good first step.

About the author

David Barrie is a Trustee at The Pilgrim Trust, and author of Incredible Journeys Exploring the Wonders of Animal Navigation. Find out more at


[1] Definition of light pollution: The excessive or poor use of artificial outdoor light which takes various forms – glare, which is direct light from the fixture; sky glow or the human-created brightening of the night sky; light trespass that occurs when light falls on areas not intended to be lit; and clutter, which occurs when lights are grouped in an excessive or confusing pattern.

[2] ‘Bird–building collisions in the United States: Estimates of annual mortality and species vulnerability’, The Condor, 116(1) : 8-23, by Loss, Scott R., Will, Tom, Loss, Sara S., and Marra, Peter P., Published by American Ornithological Society. URL

[3] ‘Effects of Light Pollution – Human Health -’, Dark Sky, URL, Published 8 September 2014, Updated 5 October 2023

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