IUCN supports dark skies for nature conservation

David Welch, Chair, IUCN Dark Skies Advisory Group


While the movement to restore and protect skies from light pollution equates broadly with the world of astronomy, some ecologists and natural resource managers have been concerned about it for over a decade. The first park to have received dark sky recognition dates to 1999, when the Royal Astronomical Society of Canada accorded dark sky preserve status to Torrance Barrens Conservation Reserve, a protected area under the jurisdiction of the Ontario Ministry of Natural Resources. This spurred dark sky advocates to organize the Ecology of the Night Symposium in 2003, at which ecologists, aboriginal elders, health specialists, land managers and astronomers joined their voices tp acknowledge the impacts of light pollution, and the synergy that could come from uniting several disciplines to achieve a common objective.

Since then, the International Dark Sky Association has awarded many natural areas with dark sky status. Other astronomy-based organizations have done likewise, and a couple of protected areas have self-declared as dark sky parks through legislation. Follow the link to the “World list of dark sky parks” on this web site < dsag.darkskyparks.org > to see a list of the thirty-seven currently known dark sky parks and reserves. There is also a growing body of scientific literature on the impacts of light pollution on species and ecological relationships. This emerging awareness and management response by park agencies led the International Union for Conservation of Nature (IUCN) to establish a Dark Skies Advisory Group in 2009.

The IUCN was founded in 1948 as the world’s first global environmental organization, and is now the largest professional global conservation network. With more than 1,200 member organizations, including over 200 government and over 900 non-government organizations, it is the world’s leading authority on the environment and sustainable development. It may be best known as the organization behind the so-called “red-book” which lists threatened and endangered species. It also compiles information on protected areas, holds quadrennial world congresses on conservation and on parks, provides scientific and management advice, and coordinates capacity building opportunities for its members.

2012 motion at the World Conservation Congress

In September 2012 the IUCN held its World Conservation Congress in South Korea. DSAG took this opportunity to present to the general assembly a motion on light pollution and nature conservation. Here it is in full.


    Given that species and ecosystems function night and day, and that artificial light can interfere with organism and ecosystem functions;

    Understanding that the appreciation of cultural heritage sites in their authentic state, the enjoyment of landscape aesthetics, and a true wilderness experience may be diminished by outdoor artificial light, glare and sky glow;

    Recognizing that astronomy, both scientific and amateur, and night sky viewing by the general public are essential contributions to understanding and enjoying our natural world;

    Being aware that cultural traditions, mythology and ceremony throughout the world bear a close relationship to night sky phenomena; and

    Noting that energy efficiency, human health and personal safety are all enhanced by the use of proper lighting and diminished by excess lighting;

The World Conservation Congress, at its session in Jeju, Republic of Korea, 6–15 September 2012:


1    Calls upon environmental and natural resource management agencies to recognize that outdoor artificial light should be subject to effective standards in order to help restore and/or maintain the ecological integrity of natural areas and the commemorative integrity of cultural sites, to respect traditional beliefs related to the night sky, and to protect species and ecosystems everywhere;

2    Suggests that urban and non-urban infrastructure management authorities regulate and control outdoor lighting in the areas under their jurisdiction so as to achieve just the right amount, spectrum and timing of outdoor lighting necessary for public use and safety;

3    Encourages natural area managers and non-governmental organizations to promote awareness of dark sky values and the need for and methods of reducing outdoor artificial light;

4    Recommends that universities, science-funding agencies, and scientific institutions foster and support research into the nocturnal aspects of biological and ecological function;

5    Urges protected area management authorities to develop visitor activities that lead to public appreciation and understanding of nocturnal ecology and the night sky; and

6    Recommends that protected area and other conservation agencies seek out opportunities to cooperate with scientific and amateur astronomy organizations and aboriginal peoples on optimum outdoor lighting design, darkness monitoring, delivery of visitor activities, and outreach related to the night sky, the nocturnal aspects of ecosystems and the importance of the night sky to traditional cultures.”

You can also find this in English, French and Spanish at < http://portals.iucn.org/2012motions/ >. The motion is number 173. The motion was sponsored by the InterEnvironment Institute, USA, and co-sponsored by: Asociación Española de Entomología, Spain; Goncol Alapitvany (Foundation), Hungary; Parks Canada Agency; Sierra Club, USA; and Universidad para la Cooperación Internacional, Costa Rica. It was passed by 100% of the government agencies present and 98% of the non-government agencies present voting in favour.

These recommendations suggest courses of action for the protection of species and natural areas. They also recognize the affinity between natural and cultural heritage values and sites. As well, they advise that the astronomy community need not, and should not, go it alone when calling for light pollution abatement and the establishment of dark sky protected areas. At the end of the day, visitors to parks and reserves should be able to enjoy seeing unspoiled nature, authentic cultural heritage and a clear night sky, and, if not there to see them directly, to have the vicarious pleasure of knowing that such things exist. Please do your part by circulating this information to your colleagues interested in dark skies. Thank you.

2021 motion at the World Conservation Congress

In 2021 the IUCN held the World Conservation Congress in France, postponed from 2020 due to the Covid pandemic. The following motion was presented to the general assembly. It was sponsored by: the Malaysian Nature Society; Ministère de l’Environnement, du Climat et du Développement Durable, Luxembourg; Ministère des Affaires étrangères et du Développement international, France; Ministère des Relations Extérieures et de la Coopération de Monaco; Muséum National d'Histoire Naturelle, France; Noé Conservation, France; and Reserves Naturelles de France. Compared to the 2012 motion it further emphasises nature conservation and public education. The motion was passed and appears here in full.


    Noting that artificial night lighting has expanded considerably worldwide generating light pollution that continues to increase by an estimated 2 to 6 % per year, and reducing darkness everywhere including in protected areas;

    Noting that the impacts of artificial light at night affect many biological groups, both flora and fauna, vertebrate and non-vertebrate, and affect the functioning of ecosystems and the free services that they provide to human societies, including pollination;

    Recalling that a large proportion of animals live partially or exclusively at night and a daily period of darkness is essential for all living organisms to alternate periods of rest and activity;

    Recognising that the outdoor lighting alters the chronobiology of living organisms and their synchronisation with their environment, in animals and plants, for example for trees by delaying the fall of leaves;

    Recognising that artificial lighting disrupts the orientation of many animal species with severe adverse effects (marine turtles, migrating birds, etc.) and reduces the quality of habitats and connectivity within landscapes, with consequences for the viability of populations;

    Recognising that artificial lighting affects trophic relationships between species, increasing foraging time available for diurnal species while diminishing it for nocturnal ones and reducing the cover of darkness for both predators and prey;

    Noting that artificial light obscures the anti-predator, luring and courtship signals of diverse bio-luminescent organisms including fireflies and glow-worms;

    Recognising that the impacts of light wavelengths on biological groups are very diverse (e.g. orientation, growth, phototaxis, circadian clock, activity modification) and that a biological group can be affected by several types of impact;

    Recognising that some wavelengths have more impact on biological groups than others;

    Noting that the outdoor lighting fleet is now either gradually being replaced or newly installed using light-emitting diode (LED) technologies that can lead to an increase in lamp intensity and a significant proportion of blue in their light spectrum that presents a risk for living organisms and increases sky glows, and that finally often results in an increase in the intensity of light together with the energy savings they provide;

    Recognising that awareness of light pollution is still low among most states, local authorities and private actors;

    Acknowledging that the purpose of some lighting is to protect human life, as well as property;

    Noting the importance of urban development and the number of places lit at night with no purpose and their contribution to energy waste and then to climate change; and

    Noting that a volume on dark skies and nature conservation in the IUCN Best Practice Protected Area Guidelines Series is being prepared by the Dark Skies Advisory Group of the Urban Conservation Strategies Specialist Group of the World Commission on Protected Areas;

The IUCN World Conservation Congress, at its session in Marseille, France:

1    Calls on the Director General to assist efforts of Members and Commissions to reduce light pollution;

2    Recalls that it is everyone’s duty to ensure the protection of the nocturnal environment;

3    Calls on all IUCN Members and agencies that manage land and water areas to develop, disseminate and implement engagement, education and outreach programmes to explain the harmful impacts of light pollution, the benefits of preserving natural darkness, and methods to reduce light pollution, with such programmes being directed at all appropriate stakeholders, including but not limited to, visitors, users, private and corporate residents;

4    Encourages authorities in charge of the planning and management of outdoor lighting to examine the utility of existing lighting and then i) to remove the unnecessary light points (i.e. those not necessary to ensure the safety of humans or property) and ii) to adapt the remaining lighting as closely as possible to the needs, incorporating several options:

      a    defining the useful illumination level, so as not to risk over-lightning, which may cause biodiversity perturbations;

      b    reducing the lighting time at night, in particular by switching off in the middle of the night;

      c    avoiding upward lighting by choosing a fixture with the light fully shielded and ground-level downward-directed;

      d    avoiding any illumination of a natural environment (unless safety is at stake);

      e    limiting the risk of glare for nocturnal species avoiding outdoor lights that exceed international agreed standards; and

      f    choosing wavelengths that have the least impact on terrestrial species according to the knowledge, which indicates to this day to favour amber lights with little blue;

5    Recommends that natural environments should not be illuminated in order to reduce or avoid pollution, unless safety is at stake;

6    Recommends that authorities identify, preserve and restore naturally dark infrastructure (i.e. ecological networks formed by cores linked by corridors which are both characterised by a natural level and periodicity of night-time darkness) to facilitate the functioning of healthy, species-rich nocturnal environments;

7    Recommends that agencies funding research support research and evidence synthesis on the effects of artificial night lighting on species and that research organisations and universities set up corresponding research programmes; and

8    Recommends that agencies raise awareness by collaborating with states, local authorities and private actors on educational programmes that address the effects of artificial night lighting and measures to reduce light pollution.