Hillary Clinton just released her climate and energy plan, which can be read in full here. The broad outlines are just as audacious as what Edwards and Obama have proposed. She'd aim to curb U.S. greenhouse gas emissions 80 percent from 1990 levels by 2050—a goal urged by a growing number of scientists and green groups—through a cap-and-trade regime, with the pollution permits auctioned off rather than given away for free. That last bit is a key design point (see here for a handy explanation), and would help avoid some of the problems plaguing Europe's emissions-trading system.

Looking this thing over, it's hard to agree with folks like Ted Nordhaus and William Shellenberger that environmentalists have lost their way in recent years. After all, a few years back, an 80 percent reduction in greenhouse gases and 100 percent auction of pollution permits was considered a fringe position on energy policy. Now all of the leading Democratic presidential candidates are advocating just that. It's a seismic shift by any measure.

P.S.: Okay, one criticism: It'd be nice if this plan included stronger measures to ease the burden on low-income households (along the lines of what Obama has proposed). As Robert Greenstein recently told Congress, even a modest reduction in emissions could, potentially, raise energy bills for the bottom 20 percent of households by $750-$950 a year. The sort of home-efficiency and weatherization programs Clinton is proposing would help mitigate that, but those take time to implement.

Alternatively, argues Greenstein, with just 15 percent of the revenue generated by auctioning off pollution permits, policymakers could offset the higher energy costs for low- and middle-income Americans through tax credits or rebates—and still have plenty of money left over to fund public transportation, R&D, and whatnot.

P.P.S. Dave Roberts has more nits to pick with Clinton's proposals here, but still gives her plan an "A" overall (from an environmental standpoint, that is). That seems about right. There are lots of things I'd quibble with, too—the fact that Clinton's only proposing to spend $1 billion a year to bolster public transportation and pays scant attention to land-use issues—but Congress is going to fiddle with these secondary details anyway. It seems to me that the broader goals are what's important for a presidential campaign platform, and Clinton's laid down all the right markers.

The main thing that might distinguish Clinton from Obama and Edwards on this front is that she's a lot cozier with corporate lobbyists, which, I guess, could make it more likely that she'll be less vigilant about pointless industry handouts and giveaways when it comes time to put together legislation. Maybe there's not a huge gulf between the candidates in that regard. Either way, that seems more important in the grand scheme of things than a side-by-side comparison of the little bells and whistles in each of the candidates' climate and energy plans.

--Bradford Plumer