by
Susan Cosier
science
tech
plentycurrent
Science and Tech
Business
Nature
Night
Light
The breathtaking annual
Perseid meteor shower in
Joshua Tree National Park.
photo by Wally Pacholka
Scientists are combatting light pollution in some
of the nation’s most pristine areas
Stargazing is best on the cold, dry nights
of winter, when the haze and smog that veil
the heavens much of the year give way to
crystal-clear skies. Yet in much of the US, it’s
increasingly difficult to make out any but
the brightest stars thanks to the prevalence
of outdoor lighting. That’s why scientists
are trying to keep some of our most pristine
locales in the dark.
The National Park Service (NPS) now considers protecting the night sky part of its mission to
preserve scenery. The agency’s Night Sky Team
is working to reduce light pollution at more than
50 parks. A four-person team of scientists measures the parks’ nighttime brightness, helps
rangers switch to dimmer lights, and develops
education programs for visitors. New government funding will allow the team to collect
data from more parks to better understand the
threats of light pollution. Chad Moore, an earth
scientist who formed the team in 1999, says
these efforts allow visitors to get something
they can’t get anywhere else: “an inspirational
view of the cosmos.”
But that view is in danger of being lost.
Light pollution can travel 200 miles and mask
easily recognizable constellations like the Big
Dipper; in fact, two-thirds of Americans can’t
see the Milky Way from their homes. Development around parks has been tainting previously unpolluted night skies. According to one
2006 analysis, since 1990, more than 1.3 million
people had moved into counties surrounding
six popular parks, including Everglades and Yellowstone. Some fear the problem will only get
worse. A 2001 study found that by 2025, even
deserts and other remote places will be bright—
meaning folks throughout the US will see at
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most 100 stars from their yards. And the glare
disrupts more than stargazing: It can distract
turtle hatchlings from finding the ocean, divert
birds from migratory paths, and alter amphibians’ hormone production.
Moore, however, says the situation isn’t so
dire. Some cities and states are already switching their outdoor fixtures to low-intensity and
shielded lighting, dimming the glow and saving
money. And when national park visitors view
the constellation-filled heavens, “they go home
unsatisfied with what they can see in their
backyards,” which could entice people to think
twice before adding outdoo r lights.
“This is a special resource, so we need to
do all we can to educate the public,” says
Bryan Faehner of the National Parks Conservation Association. “Then future generations
can experience it and be inspired.” ✤
Ask A Scientist
Is spring coming earlier due to climate change? Mike Dettinger, hydrologist at Scripps Institution of Oceanography
There are a number of ways of trying to figure out when spring arrives.
One measure is when the snow starts to melt. Another is precipitation;
studies have found that across most of the Northwest over to New
England, more rain falls now than snow. Other studies show there’s less
snow on the ground on April 1 now than there was in the 1950s. Most
rivers rise earlier, and some plants have been greening earlier. By all
these measures, we can say that spring is coming earlier.
There are few places where we could explain even half of the hastening of spring by natural forces alone. We’ve seen warmer springs
and earlier onset over the last 30 to 50 years, which makes sense,
because in that time we’ve dumped a lot more greenhouse gases
into the atmosphere than we did in the early 1900s. Whether these
trends accelerate or just keep eroding away at when spring arrives
will depend on how much people reduce greenhouse gas emissions.
Temperatures will rise and the arrival of spring will keep getting
earlier pretty much in proportion to the amount of greenhouse gases
going into the atmosphere.
—as told to Sarah Parsons
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