On Tuesday the board of Supervisors in San Francisco approved the first and only mandatory composting and recycling law in the country. While recycling is mandatory in some other states, composting is not.

The aggressive policy is aimed to drastically cut greenhouse gas emissions—particularly methane, which is more than 20 times more potent a greenhouse gas than carbon dioxide—and to eliminate transport of these recyclables and compostables to landfills and incinerators by 2020. San Francisco already diverts 72 percent of its 2.1 million tons of annual waste away from landfills. City officials claim that if the recyclables and compostables that do go to landfills are diverted, as much as 90 percent of San Francisco’s waste will stay out of landfills and incinerators.

A June 2008 report by the Institute for Local Self-Reliance found that cutting out the compostable and recyclable waste sent to landfills and incinerators would be like closing 21 percent of U.S. coal-fired power plants.

Some critics claim the law goes too far and the fines associated with the program are excessive. Small businesses and individuals can be fined up to $100 and large businesses and multiunit buildings face charges from $500-$1000. City officials, however, said the fines won’t take effect until 2011 and will be levied only in "the most egregious cases" (i.e. after several warnings). The aim of the law is not to create a new "garbage police," but rather to actively take steps to reduce greenhouse gas emissions and mitigate climate change.

The minimal effort required to sort your trash into three bins lessens greenhouse gas emissions, provides nutrients for soil (mainly sent to vineyards in Sonoma and Napa… better wine, yes please!) and will hopefully encourage cities across the nation to do the same.

Find out what to put in which bin here.