Imagine picking up a bag of dog food... or three. Or six fat cats. That's about 100 pounds, and that's how much carbon dioxide this innocent little 60 watt light bulb puts into the atmosphere before it burns out. In comparison, a compact fluorescent, or CF, light bulb will last about 10 times as long before it needs to be replaced and keeps 80% of the CO2 out of the atmosphere.
We've heard it all before: CFs flicker! the color of the light is icky! they're too bright! they're too dim! But consider this: today's compact fluorescent CF bulbs are much improved from those that were available just a few years ago: you can even find dimmable bulbs.
Before you go shopping, here are two terms you should know.
Brightness is measured in lumens:
One candle puts off about 12 lumens
Most 60-watt incandescent bulbs are about 640 lumens
Most people are used to buying bulbs by wattage, and manufacturers of CFs have tried to allow for this by indicating equivalents. But these seem to vary between brands: a 60 watt bulb may be equal to a 11, 13, or 15 watt CF. Compare lumens instead -- it should be printed somewhere on the package -- and you'll know what to expect.
Whether light seems warm or cold is measured in degrees Kelvin:
1850 K, very warm, like candlelight
2800 K, warm, like incandescent light
3000 K, warm and "bright," like halogen light
5000 K, daylight at noon
Color temperature is complicated: Wikipedia explains it well if you're interested. In short, to get a warm, cozy glow, look for bulbs with a color temperature of 2800 K; this is the same as old fashioned incandescent bulbs. For a brighter, whiter light, more like halogen, look for bulbs around 3000. New "daylight" CF bulbs go towards 5000 K and emit a very blue light that makes some people feel more cheery. The better manufacturers print the degrees kelvin information on the package; if it's not there, ask, or buy another brand.