對抗光污染，請把黑夜還給我！

Last July， France—including the City of Light—grew darker late at night as one of the world’s most comprehensive lighting 1）ordinances went into effect. From 1 a.m. to 7 a.m.， shop lights are being turned off， and lights inside office buildings must be 2）extinguished within an hour of workers leaving the premises.

Until recently， efforts to restrain our use of light have been primarily in response to the 3）astronomical light pollution erasing starry nights. But researchers are increasingly focusing on the impacts of so-called 4）ecological light pollution， warning that disrupting these natural patterns of light and dark， and thus the structures and functions of 5）ecosystems， is having profound impacts.

The problem is worsening as China， India， Brazil， and numerous other countries are becoming increasingly affluent and urbanized. Satellite views of the Earth at night show vast areas of North America， Europe， the Middle East， and Asia glowing white， with only the world’s remotest regions—Siberia， the Tibetan 6）plateau， the Sahara Desert， the Amazon， and the Australian outback—still cloaked in darkness.

Technological advances such as LEDs， or light-emitting 7）diodes， can improve our ability to reduce and better regulate lighting， but these same new lights may actually make things worse because they contain heavy doses of a “bluerich” white light that is especially disruptive to 8）circadian rhythms.

Some 30 percent of 9）vertebrates and more than 60 percent of invertebrates are 10）nocturnal， and many of the rest are 11）crepuscular—active at dawn and dusk. All are potentially impacted by our 12）burgeoning use of artificial light， scientists say.

Every flip of a light switch contributes to altering ancient patterns of mating， migration， feeding， and 13）pollination， with no time for species to adapt. On the Caribbean island of 14）Tobago， a 2012 study of 15）leatherback turtles—a species that has roamed the Earth for 150 million years—found that “artificial lighting of the nesting beaches is the biggest threat to survival of 16）hatchlings and a major factor in declining leatherback turtle populations.”

Many migrating birds， drawn off-course by artificial light， join the breathtaking number—between 100 million and 1 billion—killed each year by 17）collisions with human-made structures. For moths， which help pollinate the world’s flora， our outdoor lights are irresistible flames， killing countless moths and other insects， with ripple effects throughout the food chain.

Of course， “humans are animals as well，”explains Steven Lockley of Harvard Medical School’s Division of Sleep Medicine， “and so when light/dark cycles mess up seasonal patterns of trees or breeding cycles of 18）amphibians， there’s no reason to think it’s not doing the same to us.”

As recently as 1980， humans were thought to be immune to the effects of artificial light at night. But continuing research has shown that nocturnal light disrupts our sleep， confuses our circadian rhythms—those 24-hour biological processes that regulate our body’s functions—and impedes the production of the hormone 19）melatonin at much lower levels than previously thought possible.

More and more of the light we see at night—whether it’s from electronic gadgets or outdoor lighting—is rich with the blue wavelengths most disruptive to our body’s rhythms. （More than any other wavelength， blue wavelength light tells our brain that night is over， that morning’s blue sky has returned， and that the day has begun—the opposite signal that we want to be sending our brain in the middle of the night.） Studies continue to suggest that the consequences of excessive exposure to light at night include an increased risk for obesity， diabetes， and 20）cardiovascular disease.

Last year， the American Medical Association issued a statement calling for increased research into the “risks and benefits of occupational and environmental exposure to light-at-night，” and recommending “new lighting technologies at home and at work that minimize circadian disruption.”

In fact， researchers are concerned about the impact of some new lighting technologies. While their capacity to be computer-controlled and directed could make LEDs a key tool in reducing light pollution， these lights may actually make things significantly worse. Touted as energy-efficient and clearer in color， most LEDs currently being installed are often brighter than the old lights they are replacing， further increasing light pollution. In fact， as explained in a recent article from the Journal of Environmental Management， LEDs could “21）exacerbate known and possible unknown effects of light pollution on human health （and the） environment” by more than five times.

In the Journal of Applied Ecology， researchers have identified numerous practical steps to reduce light pollution： changing the 22）spectral 23）composition of lighting （especially LEDs）， limiting the duration of lighting， reducing the “24）trespass” of lighting into areas not intended to be lit， altering the intensity of lighting， and preventing areas from being artificially lit in the first place.

The relatively simple act of shielding our lights—installing or 25）retrofitting lamp fixtures that direct light downward to its intended target—represents our best chance to control light pollution.

Experts say it is far more important to use light effectively than abundantly. Explaining France’s new lighting rules， Delphine Batho， until recently France’s environment minister， described the government’s desire to “change the culture” to include the responsible use of light. This change is to be applauded， for what increasing numbers of studies—as well as our own eyes—tell us is that we are using far more light than we need， and at 26）tremendous cost.

去年七月，自世界上最全面的照明條例實施以來，整個法國，包括“光之城”巴黎，在深夜都變得相對黯然了。從凌晨一點到七點，商店的燈都必須關閉，寫字樓內的燈必須在員工離開后的一小時內熄滅。

直到最近，對照明使用的限制措施主要都是為了應對天文光污染令星空日漸消失的問題。但是研究人員越來越關注所謂的生態光污染的影響，警告說對這些光與暗的自然模式的干擾會引發生態系統在結構和功能上的紊亂，繼而產生深遠的影響。

由于中國、印度、巴西和眾多其他的國家日益富裕和城市化，這個問題也日漸嚴重。夜晚的地球衛星視圖顯示，北美、歐洲、中東和亞洲大部分地區光如白晝，只有世界上最偏遠的地區——西伯利亞、青藏高原、撒哈拉沙漠、亞馬遜地區、澳大利亞內陸地區——仍然隱匿在黑暗之中。

技術進步的成果，諸如LED燈，即發光二極管，能令我們減少使用照明，提高對照明的掌控，但是這些新型光源實際上可能使情況變得更糟，因為它們含有大劑量的“富含藍色波長”白光，對于晝夜節律尤其具有破壞性。

大約有30%的脊椎動物和60%以上的無脊椎動物都在夜間活動，還有許多動物會在黎明或者黃昏時活動?？茖W家說，所有這些動物的行為都可能會因人造光源的濫用而受到影響。

每一盞燈的開關都瞬間改變著生物交配、遷移、進食和授粉的古老模式，沒有時間讓物種自然適應。在加勒比海島上的多巴哥，2012年的一項關于棱皮龜的研究——棱皮龜是一個在地球上生存了1.5億年的物種——發現“其筑巢海灘上出現的人工照明是孵化幼崽存活的最大威脅，也是棱皮龜數量減少的最主要因素。……