The 12-month running mean for Mauna Loa CO2 levels is currently at 396.18 ppmv.
With a climate sensitivity of 0.809ºC/W/m2 (3ºC per doubling CO2), that translates to warming of
ΔT = λΔF = λ*[5.35 W/m2 * ln(C/C0)]with just the CO2 levels of today. However, that climate sensitivity value is just the 100-year value. At longer time spans (i.e. 1,000 years), sensitivity is actually closer 1.618ºC/W/m2. That means that at today's CO2 levels, we're already committed to 3ºC of warming over the next millennium. The key phrase? "At today's CO2 levels." And that's the main problem I have with how President Obama is approaching the whole issue.
ΔT = 0.809ºC/W/m2 * [5.35 W/m2 * ln(396.18 ppmv/280 ppmv)]
ΔT = 1.50ºC above pre-industrial levels
The "all of the above" approach sounds good—and partially insulates the president from right-wing attacks—but it does little to stabilize CO2 levels. We're still pumping out fossil fuels, still burning them for energy, still dumping the waste CO2 into the atmosphere. CO2 levels have been climbing at an average +1.484 ppmv per year since 1958 and that rate has been accelerating by an average of +0.01196 ppmv per year2. If we continue accumulating CO2 at the same rate, CO2 levels by AD 2100 will be 670.81 ppmv and we'll be locked into 3.78ºC of warming by AD 2200 and 7.56ºC of warming over the next millennium. Considering the observed consequences of just the 0.8ºC of warming we've already experienced and the projected consequences of future warming (i.e. Sherwood and Huber. 2010; Chapter 14 of the IPCC AR5 report; Levermann et al. 2013), to say nothing of methylmercury emissions, landuse changes, etc associated with fossil fuels, any energy plan that does not phase out fossil fuels (yes, ALL fossil fuels) and quickly is simply irresponsible to future generations. That is the main issue I have with the president's approach—it does little to phase out fossil fuels. While I realize that nothing will get through the current do-nothing Congress, we need to at least start a serious conversation on phasing out fossil fuels by whatever means necessary. And the longer we wait to have that national conversation and phase out fossil fuels, the more expensive it will be. The science on climate change is clear. The Earth is warming and technology is the reason. Now we need to ignore the squawks of the flat-earth science deniers and act on the science.
So, what could we do to phase out fossil fuels? The policy I favor is to put a price on carbon emissions via a tax-and-rebate system on fossil fuels but I know that isn't everyone's preference.