The candles people will be lighting during Earth Hour will release more carbon than the light bulbs they turned off.
The environmental movement has produced truly a mixed bag of results since I attended the first Earth Day in 1970. Sometimes they miss the point entirely - as in their obsession with plastic grocery bags. (Seriously, what would they have us use for garbage bags?)
Sometimes regulations help (especially when properly enforced) but sometimes good sense and self-interest is what's needed. Industries moved from more polluting processes when they learned they could often *save* money using alternative processes, recovering waste byproducts, etc. But environmentalists also damaged whole economic sectors when they denied water for agriculture to "save" some tiny fish.
Some have made environmentalism their new faith, one bordering on idolatry in their worship of Mother Earth. When they throw bad science, anti-globalism and anti-capitalism into the mix they truly lose their way.
Observant people use Shabbat clocks, and if anything, use more electricity than on a regular day, because they are keeping lights on even if they aren't in the room.