An interesting news report is circulating around the blogosphere today. Allegedly, the Bush administration is going to propose we limit CO2 to 450 ppmv by the year 2106.
If true, this as an incredibly important event --- it will move the debate from "should we take action?" to "what action should we take?" In other words, the debate will evolve into a discussion of what the target should be --- and this is (in my opinion) exactly what we should be talking about.
The long lifetime of CO2 in the atmosphere means that we cannot wait for 50 years to start reducing emissions if we want to hit 450 ppmv. In fact, we need to start deviating from our baseline in the next 10 years or so in order to avoid having to make large and disruptive cuts later. And the near-term actions required are pretty much the same for a wide range CO2 targets and timelines. Thus, while some will critize the target date of 2106, it will be one or several decades before actions in pursuit of this target preclude more ambitious targets.
ps: I've turned on "comment moderation" on the blog as a test, so your comments might take a few hours to appear. Your patience is appreciated.
[Note added later: The more I think of this alleged proposal, the more puzzled I am about it. The target (450 ppmv) and the time period (2106) are not really consistent. It is almost certainly the case that in order to stabilize CO2 at 450 ppmv at the beginning of the 22nd century, one has to be close to or at that target in the middle of the 21st century. So why put the target date 50 years later? Perhaps this is a cynical election year ploy, as suggested by several commenters. Or maybe there's something I'm not considering. Any thoughts on this are welcome.]