The Strange Scourge of Light Pollution — Transcript

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1. 0:00In January 1994, a 6.7-magnitude earthquake knocked out power in Los Angeles.
2. 0:05In the following hours, emergency services fielded an alarming number of phone calls
3. 0:09from people asking if the big silvery cloud hovering in the night sky somehow caused the
4. 0:14quake.
5. 0:15They were referring to the Milky Way.
6. 0:17Which is maybe a little sad on several levels, but not all that surprising.
7. 0:22About two-thirds of Americans, and half of all Europeans, can no longer see our own galaxy
8. 0:28in the night sky.
9. 0:29Why?
10. 0:30Light pollution.
11. 0:31It started innocently enough, eons ago, with fire, and then oil lamps and candles, and
12. 0:36then, not too long ago, electricity.
13. 0:37Since the first electric street lights appeared in the late 1870s, our world, indoors and
14. 0:42out, has been awash in the glow of artificial light.
15. 0:45At this point it’s so ubiquitous that most of us don’t even notice it until it suddenly
16. 0:49goes out.
17. 0:50Today we’ve got lights rigged everywhere -- buildings, billboards, streetlights, stadiums,
18. 0:54yards, and parking lots.
19. 0:55If you live in a city or even a suburb, it can be hard to find any real darkness these
20. 1:00days, let alone look up and see many stars.
21. 1:02Of course artificial light isn’t evil.
22. 1:04It’s awesome.
23. 1:06We all use it; it’s done a lot for us.
24. 1:09That’s why we invented it and pay lots of money for it.
25. 1:12But much of our outdoor artificial lighting has made life more difficult -- and not just
26. 1:16for frustrated astronomers and light sleepers.
27. 1:18We’re starting to see just how dangerous light pollution can be to our environment,
28. 1:23our wildlife, and even our own health.
29. 1:31[INTRO]
30. 1:37Light pollution!
31. 1:38Let’s define it as the adverse effects of excessive artificial light, and it comes in
32. 1:42lots of different forms.
33. 1:43Urban sky glow, for example, is the overall brightening of the night sky, caused by light
34. 1:47being scattered by water or particles in the air.
35. 1:50It’s that bright halo that appears over cities at night and keeps urbanites from seeing
36. 1:55stars.
37. 1:56According to the International Dark-Sky Association, LA’s skyglow can be seen from an airplane
38. 2:00200 miles away.
39. 2:02Light trespass, meanwhile, happens when artificial light falls where it is unwanted, like how
40. 2:06your neighbor’s floodlight shines directly onto your otherwise nice and dark pillow.
41. 2:10Glare occurs when super-bright lights aren’t properly shielded and shine horizontally.
42. 2:15It decreases visibility and even be dangerously blinding at times.
43. 2:18And finally there’s clutter, the general bright, bombastic, and over-the-top combination
44. 2:22of various light sources in over-lit urban areas.
45. 2:25Think like the Las Vegas Strip, or Manhattan.
46. 2:27Clutter contributes to urban sky glow, light trespass, and glare, and just demolishes any
47. 2:32nighttime ambiance.
48. 2:33You can measure a landscape’s night-sky brightness, astronomical observability, and
49. 2:37light pollution using an assessment scale called the Bortle Scale.
50. 2:41John E. Bortle created the scale in 2001 to help amateur astronomers compare stargazing
51. 2:46spots.
52. 2:47The scale ranges from one to nine, one being the darkest of wilderness skies, and nine
53. 2:52being the dense inner-city skies that so frustrate star-gazers.
54. 2:56It’s easy to imagine how light pollution interferes with our ability to study the sky.
55. 3:00All that sky glow projects up as much as it does down, and it makes it hard to see the
56. 3:03more subtle lights and objects in space without special filters.
57. 3:06But all this extra light ruins astronomers’ nights in another way--it messes with their
58. 3:11spectrographs.
59. 3:12Spectrographs are instruments that record how an object’s light disperses into different
60. 3:15signature color components.
61. 3:17If you know how to read a spectrum of a celestial object, you can determine certain things about
62. 3:21it, like its mass, chemical composition, temperature, luminosity, and just what the heck it is.
63. 3:26This makes spectroscopy a vital part of astronomy, and light pollution mucks it all up, in part
64. 3:31because artificial light shows up as bright, obscuring lines in those spectra.
65. 3:36So the light that comes from mercury vapor lamps, for instance, creates a specific “fingerprint”
66. 3:41line associated with mercury, while metal halide lamps leave markers for halogen gases
67. 3:46that they use.
68. 3:47These lines break up and obscure the otherwise smooth spectra we see from celestial objects,
69. 3:51and they can be hard to filter out.
70. 3:53And as you can imagine, astronomers find this interference really annoying.
71. 3:56But excessive artificial lighting is more than an irritating variable for scientists
72. 4:00-- it’s also a huge energy suck.
73. 4:02As much as a quarter of all electricity worldwide goes to generating light.
74. 4:06A 2008 survey in Austria found that public lighting was the largest source of their government’s
75. 4:11greenhouse emissions, accounting for between 30 and 50 percent.
76. 4:15Powering the country’s nearly two million public lights consumed 1,035 Gigawatt hours
77. 4:20of electricity and released over a million tons of CO2 in the process.
78. 4:24And we all know how destructive these emissions are to our environment.
79. 4:27But the light itself can also be a very powerful biological force.
80. 4:31If you think back to your last summer night on the porch, you’ll recall lots of creatures
81. 4:36are inherently drawn to light.
82. 4:38Many of those animals get burned.
83. 4:39Meaning, they die.
84. 4:40Many flying insects swarm around streetlights, which is great for industrious spiders who
85. 4:45know where to build a web, but it can throw off the balance of an entire ecosystem.
86. 4:49Bats, for example, have different reactions to introduced lights-- some won’t cross
87. 4:53into the light, while others use it to their advantage.
88. 4:55When some Swiss towns installed new streetlamps, the European lesser horseshoe bat suddenly
89. 5:00vanished, because, scientists think, they were outcompeted by all the more light-tolerant
90. 5:04pipistrelle bats that moved in to hunt insects drawn to the light.
91. 5:08An innate attraction to light can be so strong that it can sort of mesmerize certain song-
92. 5:12and seabirds, who are drawn to searchlights on land, and the bright gas flares of marine
93. 5:17oil rigs.
94. 5:18The poor birds circle the lights over and over until they just drop out of the sky from
95. 5:23exhaustion.
96. 5:24This seemingly uncontrollable attraction is known as positive phototaxis, and while there
97. 5:28are lots of competing theories about what causes it, we still don’t understand its
98. 5:32origins.
99. 5:33Meanwhile, hundreds of species of night-migrating birds rely on constellations to navigate in
100. 5:38the dark, and researchers speculate that bright lights may short-circuit their internal guidance
101. 5:43mechanisms, causing them to smash into lit-up buildings, radio towers, and even each other
102. 5:48and the ground.
103. 5:49And, of courses, all that artificial light can also disrupt organisms’ otherwise precisely
104. 5:53timed biological clocks.
105. 5:55For a few billion years now, life on earth has evolved under a steady, dependable day-to-night
106. 6:00schedule.
107. 6:01Pretty much all plants and animals and even a lot of microbes have adjusted their activities
108. 6:06to the regularity of sunrises and sunsets.
109. 6:08But with widespread artificial light, some birds think spring has come early and start
110. 6:13breeding ahead of schedule, or migrate prematurely.
111. 6:16Nesting sea turtles, too, seek out the darkest beaches, which are becoming harder and harder
112. 6:20to find.
113. 6:21Hatchlings naturally gravitate toward the bright, reflective ocean, but get easily turned
114. 6:26around by the big, bright cabana lights behind them.
115. 6:29I could go on, you guys!
116. 6:30Light pollution disrupts the nighttime breeding choruses of frogs and toads, confuses lovestruck
117. 6:34fireflies, makes zooplankton more vulnerable to fish, and exposes a host of nocturnal animals
118. 6:39to predators, limiting their foraging and mate-finding time.
119. 6:42And somewhere on the list is us!
120. 6:45Humans need darkness, too.
121. 6:46We need that balance of light and dark in our environment to maintain our circadian
122. 6:50rhythm -- the physical, mental, and behavioral changes within a 24-hour cycle.
123. 6:55These rhythms greatly influence our sleep-wake patterns, body temperature, and the release
124. 6:58of hormones!
125. 6:59The production of the sleep hormone melatonin is regulated by a group of nerve cells called
126. 7:03the suprachiasmatic nucleus, or SCN, which sits in the brain just above the optic nerves,
127. 7:09so it’s constantly receiving information about incoming light.
128. 7:12When it registers less light, like it usually would at night, these cells ramp up the melatonin,
129. 7:16which leaves you drowsy and ready for bed.
130. 7:19But without that signal coming at regular, somewhat predictable intervals, it can throw
131. 7:23the circadian rhythm out of whack.
132. 7:25These cycle disruptions have been linked to sleep disorders, depression, obesity, and
133. 7:30seasonal affective disorder.
134. 7:31But I think that we can all agree that a lack of sleep is not that huge a deal, compared
135. 7:35to cancer.
136. 7:36Several recent studies have suggested that prolonged exposure to artificial light at
137. 7:40night increases the risk of certain types of cancer, especially breast cancer and other
138. 7:45types that require hormones to spread.
139. 7:47Some of these studies have shown that women who work night shifts have higher rates of
140. 7:50breast cancer, and in 2007, the International Agency for Cancer Research classified night
141. 7:55work as a “probable human carcinogen.”
142. 7:58The good news, if you can see it, is that of the many, many, MANY forms of pollution
143. 8:03we face today, light pollution is one of the most easily remedied.
144. 8:06Simple changes in lighting design, materials, and zoning could go a long way in limiting
145. 8:11the light pointing up into the atmosphere.
146. 8:13The International Dark-Sky Association has developed guidelines to help cities like Flagstaff,
147. 8:17Arizona -- the world’s “first international dark sky city” -- to reduce light pollution.
148. 8:23Their tricks include things like shielding light sources so they point downward, limiting
149. 8:27the lumens -- that’s the unit we use to measure perceived brightness -- that individual
150. 8:30lights can emit, and putting caps on the number of lumens emitted per acre.
151. 8:34Even Paris, the City of Lights, now requires storefronts and office buildings to turn off
152. 8:39their lights between 1 and 7 am.
153. 8:41Not the Eiffel Tower though, that can stay on.
154. 8:43Standards like these can save communities a lot of energy, money, and work toward restoring
155. 8:48some ecological integrity.
156. 8:49Not only that, getting a handle on this pollution may give us back something vital to humanity--
157. 8:54our ability to look beyond the smallness of ourselves, out into the infinite beyond.
158. 8:59It’s like what Neil de Grasse Tyson once said, “When you look at the night sky, you
159. 9:02realize how small we are within the cosmos.
160. 9:05It's kind of resetting of your ego.
161. 9:08To deny yourself of that state of mind, either willingly or unwittingly, is to not live to
162. 9:13the full extent of what it is to be human.”
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