My prediction has already been proved wrong. So far ten people have voted in the Lights Out Challenge poll, and it's equally split between those who never leave the light on, and those who pledge not to do it anymore.
I've been researching a bit about the effects of leaving lights on. I was looking for some figures about how much money we could save if we switched them off, or how much excess carbon we produce by leaving them on. But I got sidetracked when I discovered a website about light pollution.
The picture to the right is a composite photograph from space of the earth at night. You can clearly see densely populated places that glow at night from countless millions of lights. Now being able to see at night is a wonderful thing, and I think that street lighting, car headlights, lighting in our houses and so on are all of such great benefit that the energy is well spent. But shooting all that light directly up to space is not a good use of energy. Our lights should be better targeted, so the lighting illuminates only what we need to be illuminated, not the whole surrounding area. My bedroom window looks towards Manchester, and the orange sky-glow on cloudy nights is a saddening sight.
The lack of visible stars is also a loss. In 1999 we went to Cornwall to view the solar eclipse. I was heavily pregnant with Eleanor and so made regular night-time trips from our tent to the toilet block. At 2am I noticed the sky. My God, I had no idea there were so many stars. I had lived in the city my whole life, and had probably never seen a star with a magnitude less than about 2 or 3. The eclipse was a wonderful phenomenon, but that view of the cloudless night sky was just as memorable.
It is also believed that light pollution may disrupt the lifecycles of animals such as insects and birds. Many people are familiar with midnight robins, who sing under streetlights, mistaking night for the day. And everyone knows that moths and other night insects will gather around a light. When the night is filled with lights, what effect does this have on their behaviour and lifecycles? Bright lights are thought to confuse migrating birds and hatching sea turtles. And of course, astronomers hate light pollution.
I will find out about the cost and the carbon implications of leaving unneeded lights on at some point. But until I do, reducing light pollution is another compelling reason to turn the lights out.