"Sidewalk sale on Valencia Street" by Troy Holden.

You just can't top this one, Gavin Newsom. United Nations Environment Programme promises to plant a tree for every person who follows them on Twitter. Check it: "UNEPandYou: Remember, UNEP will plant one tree for every twitterer who follows @UNEPandYou by 5 June, World Environment Day. 3 days to go!" Gimmicky? Very. Legit? Um, let's hope. So far, as of 3:35 p.m., they have 4,446 followers. Might you be one more?

Tomorrow, March 29, from 8 p.m. to 9 p.m. millions of people will turn of their lights to make a statement about climate change. It's all a part of Earth Hour, a green event conceived by the World Wildlife Fund. Over 100 U.S. cities are participating in the do-goodery, including Atlanta, Chicago, Phoenix, and, of course, San Francisco. While this won't do much insofar as saving the planet--which is doomed!--it will make a dark and profound statement about conservation and the environment.

Earth Hour has some suggestions on keeping the earth green and stuff:

Simple things like turning off appliances while not in use and switching your light globes to energy efficient bulbs, will all help us reach our goal of reducing our annual emissions by 5%. Even something as simple as turning out lights when you’re not in a room and switching to cleaner sources of electricity like "green power", make a big difference.

We concur. SFist, however, cannot promote the use of energy-saving bulbs; the light they give off is atrocious. But if soft and forgiving light is not an issue with you, you might consider switching to them.

We will be shutting our electricity down for an hour tomorrow starting at 8 p.m. and hope you join us.