对抗光污染,请把黑夜还给我!

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条例实施以来，整个法国，包括“光之城”巴黎，在深夜都变得相对黯然了。从凌晨一点到七点，商店的灯都必须关闭，写字楼内的灯必须在员工离开后的一小时内熄灭。

直到最近，对照明使用的限制措施主要都是为了应对天文光污染令星空日渐消失的问题。但是研究人员越来越关注所谓的生态光污染的影响，警告说对这些光与暗的自然模式的干扰会引发生态系统在结构和功能上的紊乱，继而产生深远的影响。

由于中国、印度、巴西和众多其他的国家日益富裕和城市化，这个问题也日渐严重。夜晚的地球卫星视图显示，北美、欧洲、中东和亚洲大部分地区光如白昼，只有世界上最偏远的地区――西伯利亚、青藏高原、撒哈拉沙漠、亚马逊地区、澳大利亚内陆地区――仍然隐匿在黑暗之中。

技术进步的成果，诸如LED灯，即发光二极管，能令我们减少使用照明，提高对照明的掌控，但是这些新型光源实际上可能使情况变得更糟，因为它们含有大剂量的“富含蓝色波长”白光，对于昼夜节律尤其具有破坏性。

大约有30%的脊椎动物和60%以上的无脊椎动物都在夜间活动，还有许多动物会在黎明或者黄昏时活动。科学家说，所有这些动物的行为都可能会因人造光源的滥用而受到影响。

每一盏灯的开关都瞬间改变着生物、迁移、进食和授粉的古老模式，没有时间让物种自然适应。在加勒比海岛上的多巴哥，2012年的一项关于棱皮龟的研究――棱皮龟是一个在地球上生存了1.5亿年的物种――发现“其筑巢海滩上出现的人工照明是孵化幼崽存活的最大威胁，也是棱皮龟数量减少的最主要因素。”

许多候鸟，因为人造光而偏离航向，数目已经达到了惊人的程度――在1亿和10亿之间――每年因撞向人造建筑而死亡。飞蛾有助于世界上的植物授粉，而户外灯光对于它们，是无法抗拒的火焰，其造成了无数飞蛾和其他昆虫的死亡，引起了整个食物链的涟漪效应。

当然，“人类也是动物，”来自哈佛医学院睡眠医学部门的史蒂文・劳克雷解释道，“光/暗周期能扰乱树木的季节生长模式或是两栖动物的繁殖周期，我们没理由认为它不会对人类也造成同样的影响。”

直到1980年，人类还自认为晚上的人造光不会对自己有什么不良影响。但是持续的研究表明夜间灯光扰乱我们的睡眠，使昼夜节律变得混乱――24小时的生物进程调节着我们身体的功能――阻碍了荷尔蒙褪黑激素的产生，使荷尔蒙褪黑激素水平比以往预料的要低得多。

越来越多的夜间灯光――无论是来自于电子仪器或者是户外照明――富含蓝色波长，这种波长对我们的身体最具破坏性。（不像其他波长，蓝色波长告诉大脑夜晚结束，早上的蓝天出现，白昼开始了――和深夜我们想发送给大脑的信号是相反的。）研究持续表明，过度暴露于夜晚灯光之下，会增加患肥胖症、糖尿病和心血管疾病的机率。

去年，美国医学协会发表声明，呼吁增加对于“在职业和环境中，暴露在夜间灯下的威胁和益处”的研究，以及倡导“在家庭和工作中，利用新照明技术将昼夜节律的扰乱降到最低。”

事实上，研究人员担心的是一些新照明技术的影响。虽然，计算机的控制和定向会使LED灯成为减少光污染的重要工具，但是这些灯实际上反倒会使情况大为恶化。虽然夸口其具有节能和明晰的特点，但是大多数当前使用的LED灯比其取代的旧灯更加光亮，从而增加了光污染。事实上，正如最近一篇来自《环境管理期刊》的报道所述，LED灯会以五倍多的速度“加剧已知和未知的光污染对于人类健康和环境的影响”。

在《应用生态学期刊》上，研究人员已经发现许多减少光污染切实可行的措施：改变光源的光谱组成（特别是LED灯），限制照明时长，减少光对于无需照明地区的“侵入”，改变光的强度，以及将防止多个地区被人造光照亮放在第一位。

屏蔽光的相对简单的行为――安装或者改装灯具装置使光线向下聚焦到预定目标上――就是控制光污染最好的途径。

专家们认为，用光贵乎“效”而非“量”。最近离任的法国环境部长黛尔菲娜・巴多在提到法国的新照明规定时指出，政府希望“改变文化”，将“更负责任地使用照明”融入到新的文化意识中。这种改变值得赞赏，因为越来越多的研究，以及我们的眼睛，告诉我们，我们所使用的光远超我们所需，同时耗资巨大。