A very interesting and important article about a little studied or
discussed topic.
pankaj


Our Vanishing Night

Most city skies have become virtually empty of stars.

A starry night sky

*By Verlyn Klinkenborg*
http://ngm.nationalgeographic.com/2008/11/light-pollution/klinkenborg-text?sourc\
e=email_inside_20081106&email=inside

If humans were truly at home under the light of the moon and stars, we
would go in darkness happily, the midnight world as visible to us as it
is to the vast number of nocturnal species on this planet. Instead, we
are diurnal creatures, with eyes adapted to living in the sun's light.
This is a basic evolutionary fact, even though most of us don't think of
ourselves as diurnal beings any more than we think of ourselves as
primates or mammals or Earthlings. Yet it's the only way to explain what
we've done to the night: We've engineered it to receive us by filling it
with light.

This kind of engineering is no different than damming a river. Its
benefits come with consequences—called light pollution—whose effects
scientists are only now beginning to study. Light pollution is largely
the result of bad lighting design, which allows artificial light to
shine outward and upward into the sky, where it's not wanted, instead of
focusing it downward, where it is. Ill-designed lighting washes out the
darkness of night and radically alters the light levels—and light
rhythms—to which many forms of life, including ourselves, have adapted.
Wherever human light spills into the natural world, some aspect of
life—migration, reproduction, feeding—is affected.

For most of human history, the phrase "light pollution" would have made
no sense. Imagine walking toward London on a moonlit night around 1800,
when it was Earth's most populous city. Nearly a million people lived
there, making do, as they always had, with candles and rushlights and
torches and lanterns. Only a few houses were lit by gas, and there would
be no public gaslights in the streets or squares for another seven
years. From a few miles away, you would have been as likely to /smell/
London as to see its dim collective glow.

Now most of humanity lives under intersecting domes of reflected,
refracted light, of scattering rays from overlit cities and suburbs,
from light-flooded highways and factories. Nearly all of nighttime
Europe is a nebula of light, as is most of the United States and all of
Japan. In the south Atlantic the glow from a single fishing fleet—squid
fishermen luring their prey with metal halide lamps—can be seen from
space, burning brighter, in fact, than Buenos Aires or Rio de Janeiro.

In most cities the sky looks as though it has been emptied of stars,
leaving behind a vacant haze that mirrors our fear of the dark and
resembles the urban glow of dystopian science fiction. We've grown so
used to this pervasive orange haze that the original glory of an unlit
night—dark enough for the planet Venus to throw shadows on Earth—is
wholly beyond our experience, beyond memory almost. And yet above the
city's pale ceiling lies the rest of the universe, utterly undiminished
by the light we waste—a bright shoal of stars and planets and galaxies,
shining in seemingly infinite darkness.

We've lit up the night as if it were an unoccupied country, when nothing
could be further from the truth. Among mammals alone, the number of
nocturnal species is astonishing. Light is a powerful biological force,
and on many species it acts as a magnet, a process being studied by
researchers such as Travis Longcore and Catherine Rich, co-founders of
the Los Angeles-based Urban Wildlands Group. The effect is so powerful
that scientists speak of songbirds and seabirds being "captured" by
searchlights on land or by the light from gas flares on marine oil
platforms, circling and circling in the thousands until they drop.
Migrating at night, birds are apt to collide with brightly lit tall
buildings; immature birds on their first journey suffer disproportionately.

Insects, of course, cluster around streetlights, and feeding at those
insect clusters is now ingrained in the lives of many bat species. In
some Swiss valleys the European lesser horseshoe bat began to vanish
after streetlights were installed, perhaps because those valleys were
suddenly filled with light-feeding pipistrelle bats. Other nocturnal
mammals—including desert rodents, fruit bats, opossums, and
badgers—forage more cautiously under the permanent full moon of light
pollution because they've become easier targets for predators.

Some birds—blackbirds and nightingales, among others—sing at unnatural
hours in the presence of artificial light. Scientists have determined
that long artificial days—and artificially short nights—induce early
breeding in a wide range of birds. And because a longer day allows for
longer feeding, it can also affect migration schedules. One population
of Bewick's swans wintering in England put on fat more rapidly than
usual, priming them to begin their Siberian migration early. The
problem, of course, is that migration, like most other aspects of bird
behavior, is a precisely timed biological behavior. Leaving early may
mean arriving too soon for nesting conditions to be right.

Nesting sea turtles, which show a natural predisposition for dark
beaches, find fewer and fewer of them to nest on. Their hatchlings,
which gravitate toward the brighter, more reflective sea horizon, find
themselves confused by artificial lighting behind the beach. In Florida
alone, hatchling losses number in the hundreds of thousands every year.
Frogs and toads living near brightly lit highways suffer nocturnal light
levels that are as much as a million times brighter than normal,
throwing nearly every aspect of their behavior out of joint, including
their nighttime breeding choruses.

Of all the pollutions we face, light pollution is perhaps the most
easily remedied. Simple changes in lighting design and installation
yield immediate changes in the amount of light spilled into the
atmosphere and, often, immediate energy savings.

It was once thought that light pollution only affected astronomers, who
need to see the night sky in all its glorious clarity. And, in fact,
some of the earliest civic efforts to control light pollution—in
Flagstaff, Arizona, half a century ago—were made to protect the view
from Lowell Observatory, which sits high above that city. Flagstaff has
tightened its regulations since then, and in 2001 it was declared the
first International Dark Sky City. By now the effort to control light
pollution has spread around the globe. More and more cities and even
entire countries, such as the Czech Republic, have committed themselves
to reducing unwanted glare.

Unlike astronomers, most of us may not need an undiminished view of the
night sky for our work, but like most other creatures we do need
darkness. Darkness is as essential to our biological welfare, to our
internal clockwork, as light itself. The regular oscillation of waking
and sleep in our lives—one of our circadian rhythms—is nothing less than
a biological expression of the regular oscillation of light on Earth. So
fundamental are these rhythms to our being that altering them is like
altering gravity.

For the past century or so, we've been performing an open-ended
experiment on ourselves, extending the day, shortening the night, and
short-circuiting the human body's sensitive response to light. The
consequences of our bright new world are more readily perceptible in
less adaptable creatures living in the peripheral glow of our
prosperity. But for humans, too, light pollution may take a biological
toll. At least one new study has suggested a direct correlation between
higher rates of breast cancer in women and the nighttime brightness of
their neighborhoods.

In the end, humans are no less trapped by light pollution than the frogs
in a pond near a brightly lit highway. Living in a glare of our own
making, we have cut ourselves off from our evolutionary and cultural
patrimony—the light of the stars and the rhythms of day and night. In a
very real sense, light pollution causes us to lose sight of our true
place in the universe, to forget the scale of our being, which is best
measured against the dimensions of a deep night with the Milky Way—the
edge of our galaxy—arching overhead.


<http://ngm.nationalgeographic.com/2008/11/light-pollution/klinkenborg-text?sour\
ce=email_inside_20081106&email=inside>




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