Embedded Files
Light Pollution
With more artificial lights, the brightness of the night sky has increased by an average of 9.6 percent per year between 2011 and 2022.
With urbanisation and the rapid expansion of cities, both urban and rural spaces are constantly evolving and undergoing rapid transformations. This has meant a widespread incorporation of technology at every level within cities and as a result, artificial night lighting has become ubiquitous. This has raised concerns about 'light pollution' and its consequences, which include:
Glare – excessive brightness that causes visual discomfort
Skyglow – brightening of the night sky over inhabited areas
Light trespass – light falling where it is not intended or needed
Clutter – bright, confusing and excessive groupings of light sources
Light Pollution Impact on Humans
Numerous studies have shown that exposure to light after dusk can have detrimental impacts on all species - both human and non-human, sparking concerns about the rise of 'cities that never sleep'. While not all cities use artificial night lighting at the same scale, smaller cities and towns are increasingly trying to adopt more 'modern' urban landscapes that are brighter at night, and thus seen as more lively and prosperous, and as safe centers for entertainment and conviviality. While this investment in artificially lengthening the day has helped major cities like Hong Kong, Seoul, New York and San Francisco earn their reputations as centers of development and innovation, their residents also experience circadian rhythm disruptions, which are carcinogenic to humans. The American Medical Association recently issued concerns for human health effects because of widespread lighting with high blue content. Artificial night lighting can, therefore, expose more people to increased risks of developing cancer.
In fact, a study by the Asian Pacific Journal of Cancer Prevention shows that artificial light at night is significantly correlated with all forms of cancer, there is a strong connection between suppression of Melatonin which has led to increases in the rates of lung, breast, colorectal, and prostate cancers individually.
With the estimated light pollution growth of 6% a year, all of developed world may lose its dark skies by the end of the 21st century.
Light pollution: mid 1970's
Light pollution: 1997
Light pollution: 2025
Light Pollution Impact on Birds
Prolonged exposure to light also has negative impacts on animals, specifically birds. According to the Executive Secretary for the Convention on the Conservation of Migratory Species of Wild Animals (CMS), every year light pollution causes the death of millions of birds. Many of these are migratory birds such as ducks, geese, sandpipers and seabirds, especially those that migrate at night, and are therefore exposed to artificial light for extended periods of time as they fly over areas of urban development. There are several detrimental impacts caused by excessive exposure to such light emissions:
Bright light that floods the night sky may confuse migratory birds, drawing them to hazardous urban structures, causing them to exhaust their energy on unproductive flight, diverting them from efficient migratory routes, or leading them to collide with infrastructure.
Red light may interfere with birds' electromagnetic tracking, which is important to their navigation. Bad weather exacerbates this danger when water droplets refract light (red or otherwise) over a larger area at a time when birds are flying at lower altitudes.
Migratory shorebirds may use less preferable roosting sites to avoid lights and may be exposed to increased predation where lighting makes them visible at night.
Birds may starve when artificial lighting disrupts foraging, and fledgling seabirds may not be able to take their first flight if their nesting habitat never becomes dark.
The way light is described and measured has traditionally focused on human vision. To manage light appropriately for wildlife, it is critical to understand how light is defined, described and measured and to consider light from the wildlife’s perspective.
Animals perceive light differently from humans. Most animals are sensitive to ultra-violet (UV)/violet/blue light8, while some birds are sensitive to longer wavelength yellow/orange9 and some snakes, can detect infra-red wavelengths10. Understanding the sensitivity of wildlife to different light wavelengths is critical to assessing the potential effects of artificial light on wildlife.
To learn more about the specific ways light impacts migratory bird traffic and movement, the BirdCast team provides real-time data to track where and when traffic changes. BirdCast is a growing international Lights Out effort already underway, including in over 30 cities in North America, in proposing and implementing one solution that is as simple as flipping a switch.
Dark Skies and Lights Out
In light of these harmful impacts that exposure to artificial light has on avian species, many efforts are underway both within the US and the international community to ensure the safety and preservation of birds. The International Dark Sky Association and Lights Out movements have been formative in spreading awareness across communities about the dangers of light pollution. Both embrace measures to make buildings and homes, especially their windows, more bird friendly. And during nighttime hours, lights out campaigns offer a critically important opportunity to reduce/eliminate nocturnal and diurnal hazards created by artificial night lighting.
Visit the INTERNATIONAL DARK-SKY ASSOCIATION website and learn more about impacts of light pollution and what you can do about it.
Visit the Audubon website and learn more about the Lights Out Program and what you can do about it.
Case Studies of Dark Skies Cities: What Has Neen Done So Far?
As part of the International Dark Sky Places (IDSP) Program many communities, parks, and protected areas around the world have adopted efforts and initiatives to preserve and protect dark sites through responsible lighting policies and public education. The case studies presented below reflect the potential and possibility for Berkeley to learn from some of its neighbors and to adopt similar practices as well.
USA Case Studies
Cupertino, CA
April 6, 2021 within the city municipal code, Cupertino adopted a Dark Sky policy: Cupertino Municipal Code Section 19.102.040 Outdoor Lighting Requirements. This change in code requires:
Outdoor lighting must be fully shielded fixtures, directed downward to meet particular needs away from adjacent properties and rights-of-ways to avoid light trespass.
Maximum light intensity on a site shall not exceed a maintained value of ten foot-candles, when measured at finished grade.
All light sources shall have a maintained correlated color temperature of 3,000 Kelvin or less.
All outdoor lighting must be fully extinguished or be motion sensor operated by 11:00 p.m. or when people are no longer present in exterior areas, with exceptions.
Lighting design standards must ensure that lighting fixture design complement the building and landscape design.
Prohibited lighting includes outdoor blinking, flashing, or rotating lights, flood lights, spotlights, and others as applicable.
Since then, Cupertino undertook a study to showcase the effectiveness and positive reception of the municipal code changes, and reported study findings at a city council meeting on October 18, 2022. A main project goal was sustainability, reinforcing a transition to LED based infrastructure - 2500 lights were modified, achieving energy savings and reduced emissions (LED lights are 50% to 70% more energy efficient, and less than half the emissions of comparable induction lighting).
In terms of budgeting, Cupertino drew up its findings both in terms of short term financial costs vs long term savings. It was estimated that the total conversion cost ranged from $1 million to $1.3 million which is not an unusual cost for a lighting project - erring more on the lower side. In the long term, the city expects to see significant reductions in lighting costs - $100,000 less annually for the first five years. This is because of LEDs having low maintenance costs. In 20 years, Cupertino expects to save $2 million with continued LED lighting as opposed to with the older induction lighting system, projected to cost $250,000 annually.
Alameda, CA
The East Bay city of Alameda introduced a Dark Skies Ordinance focused on preventing excessive lighting and glare on public roadways, and private properties. One rationale for these requirements is to “minimize light that can be attractive, disorienting, and hazardous to migrating and local birds.” The ordinance applies to new, replacements, or additions to exterior lighting, for any project that requires a building or electrical permit, but with a list of exemptions including emergency lighting, holiday displays, construction lighting, and airport lighting.[41] The ordinance prohibits use of searchlights under most circumstances, aerial lasers, mercury vapor, and other very intense lighting.[42] It also provides standards for exterior lighting, such as shielding to prevent up-lighting (except for in a few exceptional circumstances), prevention of light trespass, correlated color temperature for LED lighting, security lighting use, and parking lot, park, and street lighting.
Alameda’s ordinance also requires speicif standards:
Shielding: all exterior lighting fixtures shall be fully shielded and lighting shall be directed downward
Light trespass: exterior lighting to be directed downward, away from property lines, to prevent excessive glare beyond the subject property
It covers many types of lighting:
security lighting
parking lot lighting
service station canopies
street and park lighting
Flagstaff, AZ
Flagstaff, AZ has been a leader in the US for its commitments to preserving the dark sky. In 1958, Flagstaff passed and implemented its lighting ordinance which prohibited the use of certain commercial searchlights such as unshielded parking lot lights, yard lights - and today it has expanded its ordinance into a robust set of guidelines and rules designed to minimize the use of excess lighting in a variety of ways.
In 2001, the city became the world’s first “International Dark-Sky Community” , a designation awarded by the International Dark-Sky Association (IDA). To be IDA recognised, Flagstaff has had to meet several baseline requirements such as:
quality comprehensive lighting code
community commitment to dark skies, quality lighting, and education
broad support for dark skies from wide range of community organizations
success in light pollution control
Within the community as well, because Arizona is home to many national parks and observatories, there is much organisation at the local level to keep dark sky efforts alive. This has been done extensively through coalitions between residents, local business owners and the Flagstaff Community Foundation funding grants that can help create an education campaign that produces brochures for home-owners, posters for stores that sell lights, and activity packets for local schools. So that efforts by local gas stations or grocery stores, or even on a more official level as seen with jails, glare-free lighting designs are rewarded with funding support. These coalitions go even further, building strong ties with the Chamber of Commerce and Arizona Public Service (APS) - the local electric utility supplier. Through this coalition, in 2001 APS and the city pledged $11,000 for the "Million Lumens Campaign," which modified a million lumens of lighting by year's end.
Since 2011, the city has introduced a detailed lighting code which covers the administration, procedures and enforcement of lighting permits and policies to ensure community compliance with dark sky maintenance. It also has a special set of guidelines for sign lighting which could be followed by the city of Berkeley as well; requiring all temporary signs must be non-illuminated and allowed permanent signs may be non illuminated, or illuminated by internal light fixtures, halo illuminated, or external indirect illumination, unless otherwise specified.
More recently, Flagstaff has been releasing a new report every year on how well the community has maintained its goal to be dark sky friendly. The report provides an in-depth look at how the community has adopted various practices and been impacted by them as well. Current regulations govern the kind of outdoor lights that the city classifies as acceptable; low pressure sodium and 590 nanometer amber LEDs. These are wildlife friendly and are fully shielded, which means minimal backlight and no uplight. Additionally, Flagstaff classifies lighting into three categories ranging from Class 1 (where most light is needed) to Class 3 where lighting is strictly decorative (such as at the base of a flagpole). The city also has lighting zones, with Zone 1 having the most stringent lighting regulations, and Zone 3, while still remaining dark sky friendly, permits some leeway in terms of shielding and lumen output. Noncompliance with these regulations carries a misdemeanour fine which gives residents an even greater incentive to follow these rules.
International case studies
State of Victoria, Australia
Outside the US, many countries make serious efforts to create urban spaces that support nonhuman species. One example is the state of Victoria, Australia, which falls within the East Asian—Australasian Flyway, where migratory shorebirds breed in parts of northeast Asia (eastern Siberia and China), as far west as the Taymyr Peninsula (in the Russian Far North) and as far east as Alaska (e.g. some bar-tailed godwits). Most of these birds migrate southward before the onset of winter, with the destination for many being the warmer feeding habitats of Australia. Within Victoria, the geographically and socially diverse Port Phillip and Western Port region (including the Melbourne metropolitan region) covers 1.3 million square hectares featuring 900 wetlands, three internationally significant Ramsar wetlands, and more than 1860 species of native flora and 600 species of native vertebrate fauna. This region is critically important to both native and migratory bird species, some of which travel thousands of kilometers to forage on Melbourne’s waters.
Victoria’s localities, along with advocacy groups such as the International Dark-Sky Association of Victoria, (IDAVic, a chapter of the International Dark-Sky Association or IDA), have supported bird life by enacting measures to address artificial night light pollution. As of 2023, a number of local Councils are upgrading to energy efficient lighting, and are considering LED street lights (2700- to 3000K).
Other major efforts taking place within Australia include a set of National Light Pollution Guidelines for wildlife being issued by the Australian Government’s Department of Environment and Energy, showcasing a potential for a national scale effort to address and prioritize nonhuman as well as human needs within cities. These guidelines reinforce the intrinsic value of conserving natural darkness, as well as clean air, water and soil, in so doing supporting critical behaviour and physiological processes central to the functioning of wildlife.
The guidelines aim to manage artificial light so that wildlife is not disrupted within, nor displaced from, important habitat; and are able to undertake critical behaviours such as foraging, reproduction and dispersal. Also recommended is the use of Best Practice Lighting Design to reduce light pollution and minimize the effect on wildlife (such as lighting only the intended object or area; keeping lights close to the ground, shielded and directed; and using adaptive controls, appropriate lighting, non-reflective, dark colored surface, reduced or filtered-out blue, violet and ultraviolet wavelengths). The guidelines also recommend Environmental Impact Assessments to estimate effects of artificial night light on listed species for which artificial light has been demonstrated to affect behaviour, survivorship or reproduction. For migratory birds specifically, the guidelines offer a wide range of management actions, which can be further explored here.
A few examples of progressive protective measures include:
Using motion sensors to turn lights on only when needed, for both pedestrian or street lighting within three kilometers of a seabird rookery.
Using flashing/intermittent lights instead of fixed beams, for example, small red flashing lights can be used to identify an entrance or delineate a pathway.
Using curfews to manage lighting, this is especially for areas where birds nest, and during the fledgling period by 7 pm as fledglings leave their nest early in the evening.
Prevent indoor lighting reaching outdoor environment, which can be achieved by using fixed window screens or window tinting on fixed windows and skylights to contain light inside buildings.
Toronto, Canada
During the spring, some bird species fly from the United States, Mexico, the Caribbean or South America to reach summer breeding grounds in Canada. In the fall, they make the return journey. Many of these species migrate at night. Toronto is a major site along this route, in fact, the city was the first to raise awareness of the problem lights pose for birds in an urban center, starting in 1993 through the Fatal Light Awareness Program or FLAP - a registered Canadian charity widely recognized as the pre-eminent authority on the bird-building collision issue throughout the country. Since then, FLAP Canada has been using on-the-ground conservation, advocacy, policy development, research, awareness, education and outreach to reach millions of people. More specifically this has involved strategies such as running citizen science campaigns, volunteerism for bird recovery, rescue and rehabilitation, and by expanding their target audience by involving different stakeholders such as homeowners, the commercial industry and the government.
Toronto is also an active member of the Lights Out program, primarily targeting commercial and retail areas in the city. As part of this program, lights go out in city-owned buildings after work hours and on weekends. Moreover, the city’s Bird-Friendly Development Guidelines offer common-sense lighting practices for managing a tall building or a ground-level home. The rationale behind these guidelines is based on minimizing the negative effects of artificial lighting on both human and non-human species. It is also in line with the Toronto Green Standard which aims to improve the overall quality of life within the city through collaborative efforts between residents, planners, architects and urban designers.
Some of the main types of development that the city targets are highlighted below.
Low rise residential
Low rise residential
Use as little lights possible
Operate security lighting via motion detectors
Ensure shielded and downward facing light
Install fixtures that are Dark Sky certified
mid-high rise commercial
mid-high rise commercial
Install timers to minimize office lighting after hours via occupancy sensors
If light is needed, use of shutters or blinds, task lights to prevent spill of light
For external lighting use downward lights, as well as on building facades
Turning off signage after hours and observing limits on sign brightness and light trespass
Parks
Parks
Need to adopt fixtures that are full cutoff so that they light a pathway or sitting area without causing glare.
For park buildings, use full cutoff wall pack fixtures that are mounted at an appropriate height.
Sports lighting should also be designed to have minimum impact on surrounding areas
Birds and Berkeley’s Night Sky
Berkeley is located in the Pacific Flyway, which is one of four major migratory routes through the US. The city is also located on the San Francisco Bay, which is an aquatic environment that attracts waterfowl, shorebirds, and gulls. It has a high diversity of birds, with 201 species being observed in the Aquatic Park, located at an intersection of new developments, freeways, and Amtrak lines. Altogether, this combination of urban infrastructure plays a significant role in creating artificial lights that are harmful to the birds dependent upon this habitat.
Within the city itself there are 7850 street lights (see map on right). The most common style follows a variation of historical street light design without any shielding or downward facing light. The harm of maintaining such a design is that it allows for light to spread and spill over which threatens bird life and therefore needs retrofitting. Currently, the city does not regulate the kind of lighting that should be adopted for both public lighting (residential lighting, street and road lighting, gas station lighting, commercial district lighting), and institutional lighting (for civil buildings, historical monuments, etc.).
In 2014, the city converted bulbs for about 8000 street lights from high pressure sodium bulbs to LED for more efficiency and lower costs, and in 2019, the city faced issues with street lights experiencing elevated failure rates. However, there have been no recent efforts to address the overall design of street lights or the question of artificial night lighting more generally.
This streetlight map, based on data available on the City of Berkeley’s GIS portal captures the scale and presence of artificial light in the city. It shows that within the city’s core area, there are very few dark places. This is cause for serious concern considering the number of avian species that fly through the city and are already at risk. It also reflects the urgency for light structures to be retrofitted and reinstalled with downward lighting and shielding as the main priority.
Berkeley’s History of Dark Skies Strategies
A Dark Skies proposal was made to Berkeley’s City Council by the CEAC (Community Environmental Advisory Commission) in November 2019, based on the rationale that Berkeley become “a global leader in protecting the environment.” The proposal offers a straightforward and simple, yet effective set of solutions to reduce excessive and unwanted light pollution while conserving energy.
As part of the proposal, CEAC made a recommendation that the Berkeley Municipal Code Title 23C be amended by adding a new Chapter 23C.27 establishing bird safety requirements for new construction and significant renovations and a new Chapter 23C.28 establishing a dark skies ordinance, for review and approval.
The proposal was based on the fact that “unfettered outdoor lighting also poses known risks to birds, as well as generating unwanted light pollution. The City of Berkeley’s Downtown Area Plan, as well as Southside zoning regulations (BMC 23E.52.070.F.7), provide guidance or limitations on outdoor lighting, but no general policy exists citywide to prevent excessive light pollution from outdoor lighting.” Moreover, CEAC assessed the implications of a dark skies ordinance and concluded that the environmental benefits outweighed the burden imposed.
CEAC's dark sky proposals have not yet been adopted, but it is worth mentioning that the proposed Chapter 23C.28 : DARK SKIES states that its proposed light policy aimed "to ensure exterior light fixtures are pointed downwards and turned off whenever possible, minimising light pollution, sky glow, and hazardous risks to birds, while ensuring adequate illumination for safety, security, and the enjoyment of outdoor areas, including travel on public roads."
If passed, the new lighting policy would to be applicable to any project that requires a building permit or electrical permit for:
A. New exterior lighting, including lighting fixtures attached to buildings, structures, poles, or self-supporting structures; or
B. Additions or replacements of existing exterior light fixtures, including upgrades and replacements of damaged or destroyed fixtures.
Moreover, the proposal covers new exterior lighting and additions or replacements of existing exterior light fixtures. These outdoor fixtures must:
Be no brighter than 3000 Kelvin
Be shielded and directed
Require motion sensors or timers
In addition, the ordinance prohibits light shows and beams during migration periods (Feb 15 to May 31, Aug 15 to Nov 30).
The proposal includes numerous types of lighting that are exempt from the proposed ordinance’s requirements. Exempt categories include:
Signs
Athletic field lights
Flag lighting
Holiday displays
Low-voltage landscape lighting used to illuminate fountains, shrubbery, trees or walkways
Many of these forms of lighting could be altered, resulting in safer night lighting practices. But the exemptions remain in the draft ordinance.
Our research provides support for the Dark Skies proposal. The value of implementing such an ordinance is that it could help the city of Berkeley join its neighbours in the East Bay: Oakland, Emeryville, Alameda and across the country become a Dark Sky city that protects both its resident birds and migratory visitors.
RECOMMENDATIONS
The city should retrofit its street lights and follow specific guidelines for new lighting models and designs.
All outdoor lighting should be fully shielded, so that direct illumination from a fixture is confined to the property boundaries of the source.
Time limits should be placed on outdoor and indoor commerical bulding lighting to limit the extent of artificial light exposure.
Low-Pressure Sodium (LPS) lamps, featuring high energy efficiency, long life, and spectral characteristics, should be the preferred illumination source throughout the City. Although the city has LED lights in place, LPS lamps have additional long term benefits.
See examples of poor and effective lighting below:
Shielded downward facing light structures and designs will help with minimising glare and light spillage which causes disorientation within birds. These designs are effective for both public (commercial and streets) and private (residential) usage.
reduce unnecessary exterior light
reduce unnecessary exterior light
reduce unnecessary interior light
reduce unnecessary interior light
2. Berkeley should adopt a categorization mechanism for lighting use, with varying regulations on shielding, lumen output (amount of light produced by a bulb) and time limits. Specific efforts for bird protection could include:
Reducing the number of street lights, this may be more feasible than expecting road lights to be turned off during the fledgling and migration periods. Additionally, to address human safety concerns, speed limits can be reduced and warning signals put in place during fledgling/ migration season.
Collectively, reduced road lighting and associated traffic controls and warning signals, combined with a strong bird rescue/rehabilitation program, can help to reduce the mortality rate of migratory birds.
3. The city should proactively monitor community compliance with bird safety requirements, as other bird-friendly cities do. Annual reports and studies can be carried out to measure the success and feasibility of light improvement projects, with the help of community members, local schools and universities, and students, increasing awareness and accountability and informing future goals and targets. These reports should look at:
Bird mortality, to establish with more certainty how many birds are dying each year in Berkeley
Causes of mortality: to accurately identify the main problem areas and what accounts for bird deaths (for example, disorientation caused by upward facing outdoor lighting, car lighting etc)
Effectiveness of measures introduced, to assess what works and what does not. There are many examples of cities that Berkeley can learn from but some policies may be more location specific.
4. Berkeley should take advantage of opportunities for collaborative research, with partners such as faculty and students from UC Berkeley and Berkeley City College as well as major environmental organisations. Effective planning that is inclusive of non-human species, accurate and up-to-date data and analysis on avian population dynamics and changing human attitudes toward birds, is crucial for developing long-term strategies for the design and implementation of bird safe lighting.
For example, awareness campaigns designed and implemented by college students (nearly 40% of the city’s population), can promote the adoption of bird safe lighting practices in homes and dorms, helping to curb the impact of residential artificial lighting.
Additional resources that Berkeley City Council may find helpful:
Alameda, CA, Ordinance No. 3232 (2019)
Bird-friendly Window and Lighting Standards – Sustainable Development Code
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