Seeing the light: new moves to tackle night sky pollution
Light pollution has knock-on effects that impact whole ecosystems. From delaying wallaby pregnancies to mass-death of possums, light pollution is a threat to biodiversity that should be thought of as ‘the straw that breaks the camel’s back’ in ecosystems already under stress, says Dr Therésa Jones.
Even though artificial light at night has been identified as a key threat to biodiversity for almost a decade, it is perhaps the fastest growing form of environmental pollution, increasing at 6 percent per year globally. It has many complex negative effects on humans, other animals and plants, with growing research revealing both immediate and secondary effects that threaten ecosystems already under multiple environmental stresses.
Help from new guidelines and certification
Australia has recognised the growing importance of addressing light pollution impacts with a recent update to the Australian Standard for outdoor lighting (AS4282 2019), and the draft National Light Pollution Guidelines for Wildlife including Marine Turtles, Seabirds and Migratory Shorebirds. Consultation recently closed on the draft guidelines that were developed to address the conservation challenges posed by artificial light, which “can disrupt critical behaviours in wildlife, stalling the recovery of threatened species and interfering with a migratory species’ ability to undertake long distance migrations integral to its life cycle”. While the guidelines focus on providing “a framework for assessing and managing these impacts around susceptible listed wildlife,” they offer timely insights for appreciating the growing range of negative impacts on wildlife in general.
Responding to this urgent pollution threat, the Australasian Dark Sky Alliance (ADSA) has produced a Lighting Certification Program with three approval categories relating to levels of impact on night skies. ADSA ‘approved’ lighting has no upward light wastage. ADSA ‘prized’ certification is available to luminaries with a higher degree of performance in controlling reduction of sky glow. Finally, the ADSA ‘prized wildlife’ certification recognises an even more stringent control of light, including blue light content, for conditions where impacts on wildlife and ecologies are a vital consideration. WE-EF Lighting is the first company in Australia to have their luminaires certified.
Dr Therésa Jones is a behavioural ecologist and one of the directors of ADSA. She is a senior lecturer in evolution and animal behaviour with the School of BioSciences at the University of Melbourne and leads the Urban Light Lab. Jones spoke this month at the Australian Institute of Landscape Architects’ International Festival of Landscape Architecture to launch the ADSA approved certification which she has also worked on. Noting that human impacts on the environment are at the forefront of our minds, Jones also reflected that “light pollution is one of those pollutants that is talked about less often but we are becoming increasingly aware of.” While she sees that reducing our impacts is a necessity and could be as easy as flicking a switch, she also speaks of the need to educate everyone to be sensitive to wildlife needs, as well as our own, when choosing light sources.
In Jones’ five years experience of working in the relatively new field of light pollution impacts, she has come to appreciate that solutions need to be interdisciplinary. “Light pollution, probably more than any other pollutant, has such broad-ranging implications in terms of astronomy and human impacts, wildlife impacts, and even vegetation impacts,” she explains. The ADSA, is playing a vital role bringing experts from different fields together. Jones was approached by ADSA’s Marnie Ogg for a Dark Sky conference in September 2018 where she met a range of scientists, lighting designers, economists, people from medicine and others concerned about the impacts of light pollution.
There is no willdlife-friendly light
In developing the ADSA certification, Jones was thinking of how the discussion of light pollution might be reframed. “How might we think about it more broadly than: well, we dim the lights, we get rid of blue light, and that’s friendly to wildlife!” She was keen to change wording from terms like ‘wildlife friendly’ to ‘wildlife sensitive’. “There is no friendly lighting for wildlife at nighttime.” Or rather, she adds, the only friendly light is a changing moon, because animals have evolved to live with that. “In people’s minds, if something is ‘ecologically friendly’ then it’s fine, but this is not the case,” urges Jones. “We’re not saying it’s perfect, but we’re correctly saying it is more sensitive” and this is an important step.
Looking at animals, Jones has found a wide range of light-pollution impacts including behavioural and physiological changes. “Light at night is changing the behaviour of insects, so anything that feeds on an insect is going to be impacted – some in a good way,” admits Jones. “If you’re a bat and you like light then artificial light provides an insect sushi train for you – you can just pick them off as they go by!” But some bats are photophobic so light changes their behaviour. “If they can’t forage where they want to, they have to forage elsewhere or at a different time,” or potentially miss food entirely. “Plants can use blue light to photosynthesise so if you put that into the environment at night it suddenly changes everything for plants,” and also for when and how animals can use them.
Drawing on growing awareness of secondary effects and interconnectedness in ecological systems, citizen science is starting to play an important role in gathering data but also raising general knowledge of broad ecological issues. A moth tracker app tracks the mysterious migration of the Bogong moth which is a staple food for many animals including the endangered pygmy possum. Low numbers of moths have led to starving possums during breeding season. While Jones says that there “is a whole suite of things affecting the moths including drought and pesticides and there’s no direct evidence of light pollution effects on Bogong moths, but we need to think of light as the straw that breaks the camel’s back.”
Artificial lighting restricts or alters the movement of both predator species and prey, drawing them to different locations or changing times that they can hunt or forage. Birds singing at dawn to mark territory and find mates is happening earlier or mistimed. The flowering and germination of plants is affected and so are animals that rely on those plants. The ability to sleep or rest and share environments with other species is dictated by light levels. Extra light delays sexual maturity or otherwise alters reproductive cycles. Dr Kylie Robert led a La Trobe study which found that Tammar wallabies living in the presence of artificial light at night delayed when they gave birth, resulting in their offspring being born when their natural food sources were less available. This could have significant impacts on wallaby populations and further effects on their environments.
Real threats to biodiversity in cities
The effects of light pollution, especially when combined with the cumulative impacts of other forms of pollution, ultimately determine which species can survive in urban areas. Light pollution is an urgent problem given that “Australian cities support substantially more nationally threatened animal and plant species than all other non‐urban areas on a unit‐area basis.” Jones and the ADSA, supported by WE-EF are urging consideration of light pollution as a complex problem with at least some easy source solutions. “If you upset the balance of long-evolved systems enough you can tip it beyond the point it can manage or recover,” says Jones. Climate change and the massive risks of extinction we are facing have happened because we have reached a tipping point of accumulated small changes. Jones believes that light pollution is helping push us over the edge. “For 3.6 billion years life has evolved around the day-night cycle and now we’ve got nights that are weirdly bright. It’s going to do something.”