Imaging Satellites to Monitor the Environmental Impact and Energy Costs from Nighttime Light Pollution
Imagine a better world where you can walk outside and look up to the starry Milky Way Galaxy. A vast majority of us will never experience this or will only see the sparkling canvas overhead a few times in our life at most.
Background. According to the 2016 groundbreaking “World Atlas of Artificial Night Sky Brightness,” 80 percent of the world’s population lives under skyglow and in the United States and Europe; 99 percent of the public can’t experience a natural night. Skyglow occurs when light is emitted or reflected upward and scattered off molecules or aerosols in Earth’s atmosphere and is re-directed toward the ground. By 2050, almost 70% of homo sapiens will live in urban areas and 2.5 billion people could be added to global urban areas. Researches anticipate 90% of this increase will take place in Asia and Africa. Artificial light and skyglow after sunset is a significant contributor to climate change, global warming, and the adverse effects on terrestrial health, resources, and ecosystems.
Disrupting the ecosystem and animals. During the billions of years of evolution, prey species typically use darkness as cover and predators use light to hunt. Research scientist Christopher Kyba shares ``Near cities, cloudy skies are now hundreds, or even thousands of times brighter than they were 200 years ago. We are only beginning to learn what a drastic effect this has had on ecology.” Artificial lights tend to attract and disrupt the circadian rhythms of and have devastating effects on countless organisms including plants, corals, bats, insects, fish, turtles, marine invertebrates, primates, and many bird species. Every year humanity directly contributes to the death of millions of birds colliding with illuminated buildings and towers. “Probably more than half of the lights at night in most urban areas could be depowered”, mentioned by Kolemann Lutz, Founder at Frontier Space.
Increasing energy consumption. About 21 million tons of CO2 are emitted each year to power residential outdoor lighting in the U.S. with about 35% of all light wasted, resulting in a $3bn cost per year lost to skyglow (U.S. Department of Energy, 2011). After Los Angeles replaced 150,000+ streetlights with LEDs, the city saved roughly $8M dollars per year or more than 60% of energy costs. “Done well, LEDs could save the planet, in the sense of reining in light pollution”, mentioned by astronomer John Barentine, a member of the International Dark-Sky Association (IDA). IDA is a U.S. 501c3 nonprofit dedicated to preserving and protecting the natural nighttime environment through responsible outdoor lighting with 65-plus chapters, located in over 15 different countries. IDA hosts the International Dark Sky Week April 19–26 each year.
The resolution for Earth will stem from utilizing lower temperature light-emitting diodes (LEDs) indoors and outdoors, dimmers, motion sensors, and lighting fixtures that would shield light source to minimize glare, as well as a deeper sense of international collaboration. “Throughout North America and Europe, dark sky parks are on the rise, and festivals like Jasper’s Sky have gathered legions of amateur astronomers to the mountains. People are beginning to reconnect with the sparkling canvas that swirls overhead.”
A Solution from Geospatial Data. The global Earth Observation and remote sensing community have a fundamental role to play in quantifying the reduction of nighttime light pollution for the betterment of the health of billions of humans and animals throughout Asia, Africa, Americas, and the rest of the world. Installing quality outdoor lighting would curtail energy consumption by 60–70% while saving billions of dollars and millions of tons of carbon emissions. Specifically, light sources and illuminators closer to the infrared (IR) wavelength can be used to augment ambient light while reducing blue light. We are beginning to experience the use of infrared sources emitting near-infrared wavelengths around 700–1,000 nm for camping and lighting for national parks. If motion-activated lighting over particular locations is desirable, locals, cities, and governance might transition to better utilize the infrared spectrum at night in urban areas. “Over the past 5–10 years, we have likely experienced a 10–100x+ fold increase as a species in planet-wide utilization of the infrared spectrum on the ground, air, and space. Spacecraft in Low Earth Orbit can monitor light usage during the night time to help mitigate billions of dollars in unnecessary financial and environmental costs before lighting infrastructure emanating white light is installed in developing countries”, mentioned by Kolemann.
Imaging satellites are one of the most effective technologies and solutions to help quantify the luminosity of light pollution and shift to outdoor warmer lighting temperatures (3000K color temperature and below is recommended) to help mitigate the environmental impact. There is a global need to quantify the impact on CO2 intake and Oxygen output of plants from their disrupted photosynthesis cycles, stemming from artificial light during the night. This could potentially be generalized over large regions from observing illuminated pixels and nearby light sources with high-resolution imaging satellites with visible imaging radiometers. With machine learning and geospatial data from spaceborne and aerial platforms, we can quantify the amount of and cost savings from the installation of light posts with motion-activated sensors.
As cities adopt more environmentally friendly street lighting, low-power UV sensors on lamp posts with artificial or infrared light could help monitor the green biosignatures of flies, insects, etc. With the synthesis of object detection algorithms, we could count pixels of biosignatures of flies, moths, insects, etc. per day, week, and month and differentiate how many flies, insects, and other animals are attracted to artificial vs. infrared light. We could potentially generalize the environmental impact in ecosystems, as well as observe the positive/negative phototaxis, or bodily movement/velocity of motile organisms, as a proxy for improved navigational systems and the health of organisms.
County boards and cities have no excuse to continue spending millions of taxpayer dollars polluting our humans, plants, and environment with light in residential and parts of urban areas. A lot of street lamp posts in urban and rural centers probably do more harm to society than good because they disrupt the circadian rhythm and photosynthesis of animals and plants. With the help of remote sensing, communities could easily quantify the cost of light bulb replacement and removal. So the next time you are walking or driving by a lamp post think twice about their present-day purpose and value.
Christopher mentions, “Many U.S. communities are switching over to LED streetlights and the satellite is less sensitive to LEDs.” While space-based imaging radiometers offers a unique ability to evaluate the economic productivity of cities by observing reflectance of nighttime light spectra, there is a need to identify the nonessential, undesirable light sources and replace lighting with wavelengths closer to the infrared spectrum.
Local municipalities can adopt similar concepts to carbon-based tax incentives to reward businesses for emitting less blue light and transition to warmer color LEDs. Nations, cities, and communities could unite to incentivize low nighttime luminosity levels rather than being mostly utilized as an economic productivity metric. The values and beliefs toward light pollution that beckon from mankind allude to the notion that nighttime brightness is or would become an inaccurate means to evaluate the economic productivity of a given area.
If you were a tree, could you imagine trying to go to bed with a glaring light nearby all night? A light that is inhibiting your melanin production and deteriorating the melanin membrane protecting cells from UV radiation. Furthermore, there is also likely a direct correlation between artificial nighttime light and the development of leaves, branches, and tree lifespan that must be explored by the greater remote sensing community. Based on the early tree removal and abnormal production of leaves and branches, and possibly stunted height and root structure, there could be centuries worth of data from trees that we continue to neglect. Trees might even be inclined to grow in the opposite direction from nearby artificial white light.
The impact of not being able to view a starry night sky is underrated in our evolution above the biosphere, which is why I joined the International Dark Sky Association and encourage you to join and support them as well 0n the lifelong quest to take back our starry skies.
If we are able to truly make the sky dark again, we would look back on the mother planet that we reverse engineered away from becoming another runaway greenhouse similar to Venus. A time period we are living in where organizations and agencies united to better prioritize the environmental and humanitarian applications of geospatial data. We would share the stories with our grandchildren that would resonate well with and inspire our descendants to continue reaching for the stars.