Light pollution, biodiversity & climate change

Creatures of the night - the Lyrid meteors of 2021 Apr 22, on the trail of a foraging bat. (Richard Bassom, Wessex Astronomical Society)
Creatures of the night – the Lyrid meteors of 2021 Apr 22, on the trail of a foraging bat. (Richard Bassom, Wessex Astronomical Society)

In 2002 February, during the Lighting and Landscapes Conference at Kew Gardens, landscape architect and planner Ian Phillips, now a member of both the South Downs National Park Authority and the Council of the Landscape Institute, said: ‘Too much lighting isn’t planned. It just happens.’ This perfectly summed up the state of artificial lighting in the UK at the time, and little has changed since. The BAA Commission for Dark Skies (CfDS) still uses the quotation, for example in its recently published handbook Blinded by the Light? (

When BAA members started campaigning against light pollution in 1989, the emphasis was on saving the night sky from encroaching skyglow. That campaign has been a long learning process, and today we realise that stray light has not only robbed most of the world’s population of a view of the Milky Way’s teeming stars; there is abundant evidence that the ‘24-hour lifestyle’, modern lighting practices and the continuing lack of control and legislation of lighting are negatively affecting both human health and that of the nocturnal environment in general. It has been estimated that skyglow and intrusive light impinge upon more than two-thirds of the world’s crucial natural habitats. Rural areas are losing their night to wasted light escaping from elsewhere.

The glow-worm population of this grassy bank in rural England has been eradicated by stray light from an industrial unit. (Robin Scagell)
The glow-worm population of this grassy bank in rural England has been eradicated by stray light from an industrial unit. (Robin Scagell)

Many studies show that wildlife and its natural environments are being badly affected; symposia and meetings on light pollution are increasingly dominated by this theme. Rates of light pollution continue to increase as the ubiquitous conversion to LED lighting is being mismanaged, and overbright, blue-rich types are allowed to proliferate; in the Far East and the Middle East, where light pollution is increasing most rapidly, a very high proportion of wildlife habitats are threatened. For example, the CfDS’ Saudi Arabian correspondent Abdulrahim Hakami has published research showing worrying declines in desert species such as foxes, birds and lizards, caused by light escaping from distant cities (

The current biodiversity crash is often ascribed to the negative effects upon wildlife, and especially insects, of habitat destruction, pesticides and other aspects of modern agriculture. However, it cannot be ignored that, since more than half the world’s species are nocturnal, turning night into twilight or broad blue-rich daylight can only be harmful to creatures of whatever size which have been evolving for millions of years in harmony with the circadian rhythm of day and night.

Dr Thomas Davies of Bangor University, Wales, is an interdisciplinary conservation ecologist with a special interest in human-environment relationships. He states that ‘the consensus among the scientific community is that skyglow is probably having very widespread impacts’. A prominent member of the Institution of Lighting Professionals, the UK’s premier organisation for those who manufacture and consult on lighting, said recently that members should rein in the current spread of blue-rich LED luminaires, and that stray light is the third most potent factor in biodiversity habitat degradation.

Ecology research scientist Dr Christopher Kyba of the Research Centre for Geosciences in Potsdam, Germany, warns that the advent of misused artificial light probably represents the most drastic change humans have made to the environments of nocturnal species. In towns and cities, increasingly excessive levels of lighting not only disrupt the sleeping patterns of humans but impact upon the survival chances of urban wildlife. Songbirds sing at night as lighting triggers their dawn response. They become exhausted, and feeding and breeding are affected.

Around the world on 2019 Mar 15, many thousands of school students went on strike. They were protesting about inaction on climate change. Too few of us are acting to reduce greenhouse gases. The independent Committee on Climate Change ( has warned that the step-up in action must be substantial in every sector if we are to reach our targets for cutting emissions. Both the French and Mexican governments have recently passed national all-embracing light pollution laws regulating the direction, brightness and spectral type of exterior lighting of all kinds. Other countries and regions have regulated lighting practices. Given the current urgent need to save energy as our planet warms, and the evidence that waste light is a contributory factor to the rapid decline in biodiversity, we should be urging our administrators, both local and national, to follow suit.

Light pollution is manifestly not just an astronomers’ problem. Tackling it will benefit living things worldwide, help to reverse the warming of our world and bring the wonders of the night sky to so many who have never seen them except on screens.

Bob Mizon, Coordinator, BAA Commission for Dark Skies

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