The world is in a precarious position at the moment. Our planet is experiencing a climate crisis. Scientists expect that its effects will become more plain in coming decades. In previous posts here, we explored how outdoor lighting and light pollution interact with environmental concerns. That includes topics such as climate change, corporate social responsibility, and the "Rights Of Nature".

The laws in many countries mandate the use of outdoor lighting because it serves the public interest. Lighting has demonstrated safety benefits and saves lives. But when lighting becomes excessive, light pollution can cause its own problems. As the world transitions to renewable energy, this can create new challenges. This post explores concerns on both sides of the issue and asks whether competing interests can be balanced in reasonable and effective ways.

Artificial light at night (ALAN) has several connections to environmental concerns. For one, lighting consumes electrical power. That has a significant climate impact via the burning of fossil fuels. Also, ALAN exerts pressure on species already experiencing environmental stress. That stress comes not only from climate change, but also from sources like habitat and biodiversity loss. Energy-efficient lighting like LED seems at first like a solution the first problem. But it can also contribute to making the second problem worse.

Its lower cost of operation has led to rapid adoption of LED technology in the past two decades. With this has come overconsumption of outdoor ALAN. Outdoor lighting is now perceived to be cheap and free of environmental consequences. There is evidence to suggest that had led to the installation of a lot of new and unnecessary lighting. It may have also eliminated any overall environmental benefit from the transition to LED. And it means more light in the nighttime environment, yielding further ecological stress.

In concept, the simplest solution to the climate crisis is to reduce humanity's energy consumption. But our recent history suggests that we're not going to do that. Instead, economists expect energy demand to grow coming years and decades. If so, the next-best approach is to 'decarbonize' the global energy generation portfolio. That requires finding sources of energy that aren't limited to an exhaustible fuel supply.

"Renewable" energy sources like solar, wind and geothermal harness the power of forces of nature. These forces are at work around us all the time, their energy is "free" and it yields no polluting byproducts.  We have used some, like the wind, to power our transportation for thousand of years. Yet until recently, we couldn't move that energy from where we captured it to where we wanted to use it.
Making the best use of renewables now involves constructing both facilities to collect the energy and the infrastructure needed to move it. For this reason, people who live in areas near renewable projects often oppose their construction. Often there are real concerns about the environmental impact of these facilities. When faced with the task of evaluating applications to allow them, governments have to make difficult choices. Sometimes they conclude that the benefits involved outweigh any adverse local impact. Those impacts can include light pollution.

There are certain "speciality" lighting applications that must evaluated in their own contexts. Lighting for specific public safety applications is among those applications. Wind farms, whether built on land or in bodies of water, are a particular concern.  Wind turbines are obstacles for both pilots and sailors in both daytime and nighttime. That's true whether they're in active operation or not. Countries have set rules for lighting windmills at night to reduce the chance of accidents. These rules often supersede other concerns in environmental impact assessments.

The principle underlying these rules is that certain safety concerns cannot be mitigated. As a necessary condition of permitting wind farms, they are seen as acceptable risks. These considerations have led governments to deny permission to build some projects. In other cases, the perceived benefits are too important not to permit renewable energy projects.

Neighbors often oppose wind projects on aesthetic grounds. Their concerns about property values are often labeled NIMBYism ("Not In My Backyard"). Yet there are also real concerns about the environmental impact of this lighting. Renewables projects are often built in remote locations. These are often ecologically sensitive places. Windmills can be hazardous to birds, for example, and in particular at night for migratory species. Very large wind projects involving hundreds or thousands of turbines could light up the night sky. This may happen even when the lighting employed is the smallest amount allowed by law.

So what is the real impact, and should we worry about it? Until recently there were essentially no scientific results to inform the debate. Salvador Bará (Universidade de Santiago de Compostela, Spain) and Raul Lima (Politécnico do Porto and the University of Coimbra, Portugal) just published the first significant work on this topic. They made a simple model of the visual impact of individual wind turbine lights. They used this model to compare their expected brightness to that of astronomical sources like bright stars and planets. It takes into account real-world influences like attenuation of light by the Earth's atmosphere .

Bará and Lima found that windmill lights can be very bright at short distances. Up to 4 kilometers away, medium-intensity turbine lights can exceed the apparent brightness of the planet Venus. After the Sun and Moon, it is often the brightest natural object in the night sky. At 10 km away, the lights can still be brighter than the brightest stars. They can remain visible to the unaided eye to distances as far as almost 40 km. The authors concluded that "the visual range of wind farms at nighttime may be significantly larger than at daytime, a factor that should be taken into account in environmental impact assessments".

​So far this does not address the environmental effects of these lights. The researchers also looked at the amount of illumination on the ground that the lights can cause. Except at very close range, the intensity is low. As a benchmark, the authors used the expected light intensity on the ground from a starry night sky in the absence of the Moon. They found that even the brightest beacon lights on turbines yield these conditions out to distances of only a few hundred meters. Within 5 km the intensity is almost completely negligible. That said, it could still be harmful to wildlife very close to the windmills, whether on land or at sea.

What about the night sky? "Skyglow, in absolute terms, should not be very intense far away from the poles," Bará tells us. "The luminous intensity of the standard lamps used here at nighttime is 2000 candela, and this would make less than about 24,000 lumens per beacon, something like a couple of streetlights." Of course, if designers packed turbines into wind farms, the collective effect might be detrimental to the night sky.

​In a paper published last year, Bará and colleagues considered the effect of skyglow immediately near streetlights. They found that the contribution to skyglow from an isolated, single street light is small and localized close to the light. Small wind farms may thus have little impact on the night sky in their surroundings. But that's less likely as installations grow larger.

What can be done about all this? Clearly there is a climate need to shift energy production away from fossil fuels and toward renewables. Almost one-third of global electricity production now comes from renewables. That percentage is steadily increasing. Certain flavors of renewable energy, like solar, don't need facility lighting at night. But they're not suitable for every condition or situation. For example, electricity generated from solar cells drops to zero at night. To reduce uncertainties, experts recommend diversifying investments in types of renewables. This ensures that no one technology dominates in an area.

To the extent that wind energy is a good option in many parts of the world, there remains the question of where to put it. The social unacceptability of wind farms near populated places is unlikely to change. That leaves locations that may be especially sensitive from an ecological perspective. At the same time, transportation safety concerns will persist and even grow.

Technology may be able to help. For example, some wind farms are now equipped with Aircraft Detection Lighting Systems (ADLS). These systems sense the approach of aircraft within a predefined volume of space around and above wind farms by using low-powered radar. When an aircraft enters a predefined detection zone, the ADLS switches on bright lighting to make windmills visible to the pilot. Once the aircraft exits the detection zone, ADLS turns off the lighting automatically. ADLS can improve situational awareness of obstructions like windmills even in challenging weather. It is sometimes deployed in conjunction with Enhanced Vision Systems (EVS) equipment. EVS combines views from infrared and visible-light cameras to help pilots see through fog, snow, and other low-visibility conditions.

At the end of the day, we can't have it all. So we have to make accommodations. Situations arise where even our best technology can't fully mitigate dangers associated with wind energy projects. But where to locate these facilities remains a choice. Decisions should consider ecological sensitivity in relation to the amount of traffic and the need for lighting. In other words, it's a problem of many variables that has more than one solution. Sometimes the answer is to not build the project at all.

Dark-sky advocates have long wrestled with such tradeoffs. It is often the case that the most "wildlife friendly light" is the one that is never installed to begin with. And yet, better lighting practices exist in the real world alongside complex social and political influences. Lighting for safety remains among the most complex of them all. As the climate crisis becomes more acute, we are again confronted with often difficult choices. The right balance between competing risks serves both the interests of nature and society. That balance leads in a direction toward a world that is more sustainable in all its aspects.

We know a lot about the effects of light pollution on wildlife, the night sky, and in other areas but not as much about what it does to people. One can find some evidence for impacts having to do with physical health, wellbeing, and even social justice. Studies on mental health in particular are few, and most are about whether artificial light at night (ALAN) influences the occurrence of mental illness.

Meanwhile, as humans concentrate into cities, they become distanced from nature. Some scholars speculate on whether separation from nature can have an adverse effect. Might something similar exist having to do with loss of nighttime darkness and routine access to the night sky?

Social science has started to ask whether people experience a sense of grief or loss at environmental destruction.  The Australian philosopher Glenn Albrecht invented a word for it in 2005: solastalgia. Describing it as "the homesickness you have when you are still at home", Albrecht composed it from Latin and Greek words meaning 'comfort' and 'pain'/'suffering'/'grief'. It refers to both anxiety about the state of the environment both now and in the future.

In June 2023, the journal Science published an issue with a special section about light pollution. Some 50 years after the term first appeared in its pages, light pollution appeared on its cover. Six review papers presented a summary of what we know about this issue from scientific, social and legal perspectives.

In recent years, dark-sky activism and what is now called "community engagement" forged new connections among activists, researchers and others. Through this work I met Dr. Aparna Venkatesan, an astronomy professor and Co-Director of the Tracy Seeley Center for Teaching Excellence at the University of San Francisco.

Besides her passion for the the study of the early universe, Aparna is a tireless advocate for diversity, equity and includion (DEI) in science and society. We also share a keen interest in the social consequences of space policy, about which we co-wrote a paper published last year in Nature Astronomy.

We have had many discussions about these issues particularly since the dawn of the large satellite constellation era in 2019. We talked about all this in the broader context of loss of humanity's connections to the night sky. We also came to realize that the night sky makes up a kind of intangible cultural heritage, one worth protecting.

Aparna suggested a word that parallels solastalgia in its derivation and meaning. "Noctalgia" is a  neologism that combines roots for "night" and "pain" to suggest the sense of loss associated with the brightening of the night sky due to light pollution. In a broader sense, it encompasses any influence that changes the character of the night, including on the ground.

In August we published an 'e-letter' in Science reacting to the articles in the earlier special section and introducing noctalgia to the world. We also posted the e-letter to the arXiv, a repository of scholarly literature on astronomy and other subjects. The media picked up on the idea shortly after and ran with it. The amount of coverage surprised us (see here, here, here and here). Clearly noctalgia struck a chord.

Naming things can be an opening to talking about them with more honesty and authenticity. But we also hope that giving a voice to what some people now feel will help move them to take action. That action results from awareness that becomes a demand of society to take on and solve a problem. In turn, that relates to something called the 'issue attention cycle'.

Anthony Downs was an American economist who specialized in public policy and public administration. In 1972 he wrote an influential paper called "Up and Down with Ecology — the Issue-Attention Cycle". In it, he argued that to solve social and environmental problems they had to capture and maintain public attention. He also described a cycle of steps from identification of the problem to post-solution effects that can start the cycle over again. 

As people discover light pollution, awareness rises. According to Downs' theory, some of them will decide that a real problem exists. If it maintains prominence for long enough, a critical mass will form and people will begin demanding solutions from decision makers. Yet it's arguable that the global dark-skies movement is still climbing the "hill of awareness" and that we are not at the peak yet.

Even among those who become aware of light pollution, there's no guarantee that they will become part of this movement. Some who experience light pollution may write off the loss of the night as a consequence of progress and modernity. For example, people in developing economies may cite a need for outdoor lighting to enable safe transit at night and a nighttime economy. Given the colonial history in many such places, it's difficult to argue that they shouldn't have access to it. That's true even as we recognize the many ways that ALAN harms humans and nature.

Some people might be motivated to do something about light pollution once they give voice (and a name) to the loss they have experienced. But that presumes that they have something to lose in the first place. As the world continues to urbanize, fewer people grow up in places where they can see the stars at night. It remains to be seen whether people who never had access to dark night skies grieve something that to them was never 'lost' in the first place.

But that loss is especially acute for some people who have long suffered from deprivation. Indigenous, Aboriginal and First Nations people often live in places where the night sky is still accessible. In many instances, it looms large in their culture, folklore and religion. But these people often have little to do with creating the conditions that lead to light pollution. They also often have the least amount of political power in their countries and hence little ability to do anything about it. For many, the sense of loss is all too familiar.

There is an old saying about how the pace of change determines outcomes: Toss a frog into a pot of boiling water and it will leap out to save itself. But toss a frog into a pot of cool water, gradually warming it up, and the frog will swim around until it boils to death.

People often recognize the severity of problems at different points in time. Some are 'early adopters' of such ideas, while others are laggards that don't get on board until late in the game. And as our world changes, what society considers acceptable levels of risk may shift.

The loss of the night can prompt real, palpable grief in some people. But can noctalgia really prompt more people to take action on the problem of light pollution? We don't (yet) know whether the same is true of environmental problems more generally, or the role solastalgia plays. Meanwhile, people everywhere are straining under the weight of the many problems humanity faces. 'Crisis fatigue' is real, and it undermines efforts to solve those problems in definitive ways.

But solving the problem of light pollution turns out to be remarkably simple and cost-effective. We don't lack a technological solution — one is in hand right now. It enables us to light the world at night well for human needs while minimizing the negative effects all that light has on the environment. By reducing or eliminating wasted light, we could get a handle on the situation in short order.

Of more significance is that humanity desperately needs a win in the environmental realm. Were we to solve the problem of light pollution within a generation, the result might inspire confidence in out ability to take on bigger issues like climate change. But first, we have to finish climbing that 'hill of awareness' that moves people to action. If we do, it could be one of the defining environmental moments of the 21st century.

Summary: Most efforts to reduce light pollution to date have focused on the public sector. But as night skies continue to brighten around the world, private enterprise can play in protecting dark night skies. Corporate social responsibility (CSR) and environment, social, and governance (ESG) principles may be powerful — and thus far unappreciated — levers on the problem.

CSR and ESG are hot topics in the global corporate world. But what do they really mean? CSR establishes values and sets an agenda, while ESG turns that agenda into goals with measurable impact. In a sense, CSR makes up the "S" ("social") in ESG by operationalizing the vision that CSR establishes.

The actions of early 20th century industrialists like John D. Rockefeller and Andrew Carnegie exemplify CSR. They spent billions of dollars on social causes, the legacy of which remains with us to this day. ESG traces its roots to the South African anti-apartheid movement that began in the late 1950s. It only became well known in 2006 when the United Nations launched the "Principles for Responsible Investment."

CSR is qualitative due to the many nuances of measuring social impact. ESG criteria tend to consist of quantitative metrics. It provides a way for companies, investors and the public to check how well companies stick to the sustainability and corporate responsibility goals they set. The current understanding of ESG considers the environment a stakeholder in all businesses. No particular industry or sector is exempt.

This framework is not immune to criticism. A major disadvantage of CSR and ESG is that small businesses shoulder much of its costs. Some critics contend that they undermine the primary aim of business, which is to create (financial) value for shareholders. They can also draw unwanted scrutiny over ever aspect of a company's business. And in some cases, CSR/ESG initiatives can distract from the need for meaningful, systemic change. ​

​The corporate world now ignores CSR and ESG at its own peril. Corporate boards increasingly seek advice on how to pursue these ideas. Some now see environmental concerns as among the stakeholders that their business affects.

But much of the pressure to do so still comes from the outside. One recent survey found that almost three-fourths institutional investors do not trust companies to achieve their stated sustainability and ESG goals. Investors and regulators alike are applying pressure on companies. And it's becoming hard for them to hide the environmental and social harms associated with their activities.

What about forces operating inside organizations? There is some evidence that companies prioritizing CSR and ESG principles have increased employee productivity and reduced turnover. Other data suggest that consumers, especially younger people, prefer to buy from companies that exhibit a strong sense of social responsibility. Failing to recognize this can even cost companies more in the long run.

Light pollution is an environmental issue at its core. It involves many known and suspected hazards to plants, animals and even people. With each passing year, the weight of the evidence grows bigger. And because the world still produces some 80 percent of its electricity from fossil fuel sources, light pollution is also a climate issue.

Light pollution arguably harms businesses' environmental stakeholders, yet it costs little to nothing to undo the damage. Many businesses will find it even saves them money to reduce their artificial light at night emissions in both their supply chains and at their facilities. Companies that fail to take advantage of these savings may be seen — pardon the pun — in a bad light. It may lead to accusations that they only care about higher-profile environmental issues. In turn, that implies that their assessments of environmental stakeholder needs are inadequate.

Wherever companies operate, they extract profits from those territories and communities. As the social significance of climate change rises, it is a disadvantage when the public perceives a company is doing harm rather than good. Those that do considerable business with governments may find these concerns turn into requirements. Planning ahead to be able to react quickly to a changing business landscape conveys a clear advantage.

There is even a nexus among ESG, land use planning, the public regulatory regime, and dark skies. In countries like Wales and New Zealand, large territories are under management as International Dark Sky Reserves. Both the central governments and local councils in those places are proactive in framing light pollution as an environmental concern. ​