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| Port of Spain at 7 pm |
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 (National Geographic). Light pollution is
excessive, misdirected, or obtrusive artificial (usually outdoor) light.
The
four components of light pollution are often combined and overlapping: Urban
sky glow, light trespass, glare and clutter.
Sky glow is the illumination
of parts of the night sky. The most common cause of sky glow is artificial
light that emits light pollution, which accumulates into a vast glow that can
be seen from miles away and from high in the sky. Sky glow from artificial
lights is common throughout the world and can be observed over most cities and
towns.
Light trespass, occurring when
streetlights or a neighbour’s security light directs unwanted lighting onto our
property or into our homes, contributes to a loss of natural darkness.
Glare is difficulty
seeing in the presence of bright light such as direct or reflected sunlight or
artificial light such as car headlamps at night. Specifically, discomfort glare
results in an instinctive desire to look away from a bright light source or
difficulty in seeing a task. Glare from unshielded lighting is a public-health
hazard, especially the older you become. When glare is so intense that vision
is completely impaired, it is sometimes called dazzle.
Light clutter refers to excessive
groupings of lights. This redundant lighting is found in many urban centres
which results in a clutter of lights that contribute to sky glow, trespass, and glare while destroying the ambiance
of our night-time environment. Our eyes, when dark-adapted, have good natural
capacity in low-light situations. But when nightscapes are over-lit, eyes never
have a chance to become dark-adapted, and areas adjacent to brightly lit areas become
impenetrable, reducing safety. Groupings of lights may generate confusion,
distract from obstacles (including those that they may be intended to
illuminate), and potentially cause accidents. Clutter is particularly
noticeable on roads where the street lights are badly designed, or where
brightly lit advertising surrounds the roadways.
This picture captured in Port of Spain embodies all the aforementioned aspects of light pollution, and when I took this picture it wasn't even 7 pm yet. Imagine that!
Light pollution has many effects on both human and animal populations. In
disrupting ecosystems, light pollution poses a serious threat in particular to
nocturnal wildlife, having negative impacts on plant and animal physiology. It
can confuse the migratory patterns of animals; alter competitive interactions
of animals, change predator-prey relations, and cause physiological harm. 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 behaviour, is a precisely timed biological behaviour. Leaving early may
mean arriving too soon for nesting conditions to be right. The rhythm of life
is orchestrated by the natural diurnal patterns of light and dark; so
disruption to these patterns impacts the ecological dynamics.
With
respect to adverse health effects, many species, especially humans, are
dependent on natural body cycles called circadian rhythms and the production of
melatonin, which are regulated by light and dark (e.g., day and night). If
humans are exposed to light while sleeping, melatonin production can be
suppressed. This can lead to sleep disorders and other health problems such as
increased headaches, worker fatigue, medically defined stress, some forms of
obesity due to lack of sleep and increased anxiety. And ties are being found to
a couple of types of cancer.
Increased
urban sky glow is responsible for the disappearance of the Milky Way from our
night skies. For professional astronomers, the increasing distance to prime
observing sites, well away from sources of air pollution and urban sky glow,
becomes more problematic as economic and environmental energy costs continue to
rise (IDA). Amateur astronomers, meanwhile, find prime observing spots
eradicated by commercial and residential development and must travel farther
from home for a clear view of the skies. Increasingly, the most important
equipment needed to enjoy the wonders of the night sky is an automobile with a
full tank of gas and a map.
The
adverse effects of light pollution extend well beyond astronomy. New research
suggests that light at night may disrupt circadian rhythms, the 24-hour cycle of
day and night that regulates biological function in all life on Earth. Paradoxically,
in addition to wasting resources, a night-time environment that is over-lit
results in lowered visibility: direct glare from improperly shielded fixtures
is often blinding. Light spilling into the sky does not light the ground where
we need it.
Light
pollution affects every citizen, especially within the Port of Spain
Corporation. It is a serious environmental concern that wastes money and resources
while jeopardizing wildlife, our environment, health, and human heritage.
Fortunately, concern about light pollution is rising dramatically around the
world. A growing number of scientists, homeowners, environmental groups
and civic leaders are taking action to restore the natural night. Each of us
can implement practical solutions to combat light pollution locally,
nationally, and internationally.
References:
Globe at Night. "What is Light Pollution?". Accessed May 20, 2014.
http://www.globeatnight.org/light-pollution.php
International Dark-Sky Association. "Introduction to Light Pollution - What's the Problem?"
Accessed May 20, 2014. http://www.darksky.org/assets/documents/PG1-light-
pollution.pdf
National Geographic. "Light Pollution". Accessed May 20, 2014.
http://ngm.nationalgeographic.com/2008/11/light-pollution/klinkenborg-text
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