Light may be one of the most overlooked environmental threats to the Great Lakes, according to a project that recently mapped them.
Researchers with the Great Lakes Environmental Assessment and Mapping Project mapped environmental stressors to the Great Lakes, including light pollution.
Excessive lighting disrupts wildlife habits and habitats, said David Allan, a professor with the School of Natural Resources and Environment at the University of Michigan who led the project.
While light pollution has only a small effect on the ecosystems of the lakes themselves, it has great influence along the margins of the lakes.
“It affects movements of amphibians and mammals by causing disorientation, particularly during hazardous road crossings,” Allan said. “The biggest concern, of course, is bird collisions with illuminated buildings, and this is indeed a serious issue.”
Habitats are fundamentally altered by light pollution, according to Scott Kardel, spokesman for the International Dark-Sky Association, a light pollution activist group.
“It’s important to remember that anybody, plants, animals and humans, evolved in a world with a cycle of day and night,” he said. “Light pollution breaks that cycle. It essentially changes ecosystems in a variety of ways.”
In addition to the threat posed by tall, brightly-lit buildings to birds, predators that feed in the dark are forced to travel greater distances to find their hunting grounds, Kardel said. The effect is that any energy they gain from feeding is expended in travel to and from their prey.
There are a number of ways to limit light pollution, Kardel said.
“Some of the light at night is poorly directed,” he said, “it’s sent where it doesn’t need to go. A better job of directing it would limit the amount needed.”
An international awareness campaign targets light pollution as only astronomers can.
Reaching out to people everywhere, including the Great Lakes region, the GLOBE at Night project is attempting to build a global database of light pollution through citizen-science.
“In cases like this, no one scientist can get all the data they need,” said Connie Walker, an associate scientist and senior science education specialist with the GLOBE at Night program. “That’s the nature of citizen-science. It’s the best way to involve people in science and get a lot of data from a lot of places in a short amount of time.”
Here’s how it works
GLOBE at Night provides a series of night sky photographs on its website, each depicting different levels of light pollution. Light pollution is often measured in terms of magnitude, a scale used by astronomers since the ancient Greeks to describe the brightness of stars. The higher the magnitude, the dimmer the star appears to the earthly observer.
The GLOBE at Night program uses this same scale to gauge light pollution. Skies in which only bright stars, those with low magnitude ratings, are visible have greater light pollution than skies in which fainter stars can be seen. The brightest stars are ranked with a magnitude of one, and the faintest stars visible to the unaided eye are ranked as a seven.
“In a place like a national park, you can probably see magnitude six or seven stars,” Walker said, “in the suburbs it’s more likely that you’ll see magnitude three or fours. In cities you’ll probably only be able to see magnitude one stars.”
Light pollution has far-reaching consequences not only for astronomy, but also for wildlife and human health.
“Our program began out of astronomers’ concern to keep the night sky dark for research,” Walker said, “but it’s gone beyond that now. Light pollution has impacts on the natural environment, energy use, and human health.”
It is linked to sleep disorders and decreased melatonin levels in humans, he said. Sleep disorders arise from excessive light shining into homes, preventing restful sleep. Decreased melatonin levels have been connected to increased instances of prostate and breast cancer, particularly in night shift workers.
“There’s all these things we’re discovering about light pollution,” Walker said. “There’s a lot of researchers working around the world on this right now.”
Directing light where it was needed, rather than allowing it to be cast all around, would not only limit light pollution, but would also cut down on energy costs, he said.
These impacts are what drives Walker and GLOBE at Night to continue the program and build an accurate picture of light pollution around the world, including in the Great Lakes. The program is accepting data from participants through May 28.
“This goes beyond astronomy,” Walker said, “It has absolutely enormous environmental and health impacts.”