More recently, he has updated it:
In this post I will lay out “the solution” to global warming, focusing primarily on the 12 to 14 “stabilization wedges.”
This post is an update to “Is 450 ppm (or less) politically possible? Part 2: The Solution.”
I have argued that stabilizing atmospheric concentrations of carbon dioxide at 450 ppm or lower is not politically possible today, but that it is certainly achievable from an economic and technological perspective (see Part 1). I do, however, believe humanity will do it since the alternative is Hell and High Water.
It would require some 12-14 of Princeton’s “stabilization wedges” — strategies and/or technologies that over a period of a few decades each reduce global carbon emissions by one billion metric tons per year from projected levels (see technical paper here, less technical one here). The reason that we need twice as many wedges as Princeton’s Pacala and Socolow have said we need was explained in Part 1. That my analysis is largely correct can be seen here: “IEA report, Part 2: Climate Progress has the 450-ppm solution about right.”
I agree with the IPCC’s detailed review of the technical literature, which concluded in 2007 that “The range of stabilization levels assessed can be achieved by deployment of a portfolio of technologies that are currently available and those that are expected to be commercialised in coming decades.” The technologies they say can beat 450 ppm are here. Technology Review, one of the nation’s leading technology magazines, also argued in a cover story two years ago, “It’s Not Too Late,” that “Catastrophic climate change is not inevitable. We possess the technologies that could forestall global warming.”
I do believe only “one” solution exists in this sense — We must deploy every conceivable energy-efficient and low carbon technology that we have today as fast as we can. Princeton’s Pacala and Socolow proposed that this could be done over 50 years, but that is almost certainly too slow.
We’re at about 30 billion tons of carbon dioxide emissions a year — and notwithstanding the global economic slowdown, probably poised to rise 2% per year (the exact future growth rate is quite hard to project because it depends so much on what China does and how quickly peak oil kicks in). We have to average below 18 billion tons (below 5 GtC) a year for the entire century if we’re going to stabilize at 450 ppm (see “Nature publishes my climate analysis and solution“). We need to peak around 2015 to 2020 at the latest, then drop at least 60% by 2050 to at most 15 billion tons (4 billion tons of carbon), and then go to near zero net carbon emissions by 2100.
That’s why a sober guy like IPCC head Rajendra Pachauri, said in November 2007: “If there’s no action before 2012, that’s too late. What we do in the next two to three years will determine our future. This is the defining moment.” Or as I told Technology Review, “The point is, whatever technology we’ve got now — that’s what we are stuck with to avoid catastrophic warming.”
If we could do the 12-14 wedges in four decades, we should be able to keep CO2 concentrations to under 450 ppm. If we could do them faster, concentrations could stay even lower. We’d probably need to do this by 2040 if not sooner to have a shot at getting back to 350 this century. And yes, like Princeton, I agree we need to do some R&D now to ensure a steady flow of technologies to make the even deeper emissions reductions needed in the second half of the century.
I do agree with Hansen et al that the basic strategy is to replace virtually all of coal as quickly as possible, which is why so many of the wedges focused on electricity — that, along with the need to electrify transportation as much as possible. I also agree that this will be harder and more expensive if conventional oil were not going to peak soon. But for better or worse, it is (see “Merrill: Non-OPEC production has likely peaked, oil output could fall by 30 million bpd by 2015” and “Normally staid International Energy Agency says oil will peak in 2020“).
Also, I tend to view the crucial next four decades in two phases. In phase 1, 2010 to 2030, the world finally gets serious about avoiding catastrophic global warming impacts (i.e. Hell and High Water). We increasingly embrace a serious price for carbon dioxide and a very aggressive technology deployment effort.
In phase 2, 2030 to 2050, after multiple climate Pearl Harbors and the inevitable collapse of the Ponzi scheme we call the global economy, the world gets truly desperate, and actions that are not plausible today — including widespread conservation — become commonplace (see here for a description of what that collapse might look like).
In the basic solution, I have thrown in a some extra wedges since I have no doubt that everybody will find something objectionable in at least 2 of them. But unlike the first time I ran this exercise, I have blogged on most of the solutions at length.
This is what the entire planet must achieve:
Here are additional wedges that require some major advances in applied research to be practical and scalable, but are considered plausible by serious analysts, especially post-2030:
That should do the trick. And yes, the scale is staggering.