This week, Gov. Jerry Brown announced an executive order to cut greenhouse gas emissions by 40% from 1990 levels by 2030. It's being hailed as the most aggressive climate change policy pursued by any government in North America – but will it put the squeeze on California's metropolitan planning organizations and their sustainable communities strategies?

Brown's order has drawn attention for its combination of ambition and immediacy. But it does not come out of thin air. Brown's 2030 targets fit, substantively and chronologically, between those of Fran Pavley's 2006 law Assembly Bill 32, which mandates lowering GHG emissions to 1990 levels by 2010, and former Gov. Arnold Schwarzenegger's goals of 80 percent reduction by 2050, also established by executive order. Meeting them means that, in relatively short order, California will look, drive, and power itself far differently than it does today — especially as its population continues to rise. 

The order requires all state agencies with jurisdiction over sources of greenhouse gas emissions to participate. Agencies must prepare implementation plans by September 2015, with guidance from a technical advisory group that will be set up by the Governor's Office of Planning and Research.