The California Air Resources Board is scheduled to vote Friday on controversial regulations aimed at reducing vehicle emissions responsible in part for global warming. Many other states have pledged to follow California's lead if it adopts the tighter standards. California is the only state that can set its own emissions regulations since it began doing so before federal standards were set. Other states must adopt federal standards or California standards.

The proposed regulations aim to cut greenhouse gas emissions by 20 percent by 2009. A report by the Board supporting the proposed changes can be viewed here [PDF], while the proposed changes can be viewed here [PDF] and here [PDF]. The hearings are currently being webcast by the Board and can be viewed here. The San Francisco Chronicle has more.

UPDATE [3:19 PM ET]: The Board has voted unanimously to approve the stricter emissions regulations.