"How the world can stabilize at 350 to 450 ppm: The full global warming solution"
In this post I will lay out “the solution” to global warming.
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 ultimately reduce projected global carbon emissions by one billion metric tons per year (see technical paper here, less technical one here). These 12-14 wedges are my focus here.
This post is an update of my April 2008 analysis. A 2008 report by the International Energy Agency came to almost exactly the same conclusion as I did, and has relatively similar wedges, so I view that report largely as a vindication of my overall analysis.
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:
- 1 wedge of albedo change through white roofs and pavement (aka “soft geoengineering) — see “Geoengineering, adaptation and mitigation, Part 2: White roofs are the trillion-dollar solution“
- 1 wedge of vehicle efficiency — all cars 60 mpg, with no increase in miles traveled per vehicle.
- 1 of wind for power — one million large (2 MW peak) wind turbines
- 1 of wind for vehicles –another 2000 GW wind. Most cars must be plug-in hybrids or pure electric vehicles.
- 3 of concentrated solar thermal (aka solar baseload)– ~5000 GW peak.
- 3 of efficiency — one each for buildings, industry, and cogeneration/heat-recovery for a total of 15 to 20 million GW-hrs. A key strategy for reducing direct fossil fuel use for heating buildings (while also reducing air conditioning energy) is geothermal heat pumps.
- 1 of solar photovoltaics — 2000 GW peak
- 1/2 wedge of nuclear power– 350 GW
- 2 of forestry — End all tropical deforestation. Plant new trees over an area the size of the continental U.S.
- 1 wedge of WWII-style conservation, post-2030 [just a placeholder, will blog more on this later]
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:
- 1 of geothermal plus other ocean-based renewables (i.e. tidal, wave, and/or ocean thermal)
- 1 of coal with biomass cofiring plus carbon capture and storage — 400 GW of coal plus 200 GW biomass with CCS
- 1/2 wedge of next generation nuclear power — 350 GW
- 1/2 wedge of cellulosic biofuels for long-distance transport and what little aviation remains in 2050 — using 8% of the world’s cropland [or less land if yields significantly increase or algae-to-biofuels proves commercial at large scale].
- 1 of soils and/or biochar– Apply improved agricultural practices to all existing croplands and/or “charcoal created by pyrolysis of biomass.” Both are controversial today, but may prove scalable strategies.
That should do the trick. And yes, the scale is staggering.
[Note: For those who prefer terawatts, 1000 GW=1 TW. I have adjusted the peak GW of the renewable wedges to take into account the lower capacity factor of solar and wind. The efficiency measures are assumed to have a capacity factor of about 60%.]
Note: The albedo effort requires a more aggressive effort than described in this post, one that California Energy Commissioner Art Rosenfeld detailed to me in a recent interview, which I will blog on later.
Why not more than 1 wedge of CCS? That one wedge represents a flow of CO2 into the ground equal to the current flow of oil out of the ground. It would require, by itself, re-creating the equivalent of the planet’s entire oil delivery infrastructure. I also think that CCS has practical issues that will limit its scale, not the least of which is that I doubt it will be among the cheaper solutions — as I explained here. But the possibility of doing CCS and biomass co-firing — resulting in negative-carbon electricity that actually pulls CO2 out of the air — makes this too important a strategy not to pursue aggressively.
Why not more than 1 total wedge of nuclear? Based on a post last year on the Keystone report, to do this by 2050 would require adding globally, an average of 17 plants each year, while building an average of 9 plants a year to replace those that will be retired, for a total of one nuclear plant every two weeks for four decades — plus 10 Yucca Mountains to store the waste. I also doubt it will be among the cheaper options. And the uranium supply and non-proliferation issues for even that scale of deployment are quite serious. See “An introduction to nuclear power.”
Note to all: Do I want to build all those nuclear plants. No. Do I think we could do it without all those nuclear plants. Definitely. Therefore, should I be quoted as saying we “must” build all those nuclear plants, as the Drudge Report has, or even that I propose building all those plants? No. Do I think we will have to swallow a bunch of nuclear plants as part of the grand bargain to make this all possible and that other countries will build most of these? I have no doubt. So it stays in “the solution” for now. [Note to self: Are you beginning to sound like Donald Rumsfeld? Yes.]
This is not to say the two wind power wedges (4000 GW peak total) would be easy — but the world did build over 27 GW last year, a 36% jump from 2007. We would need to average 100 GW/year through 2050. But I do think it is ecologically and economically possible, as I think all the other wedges in the top group are, too.
But none of the wedges is easy. That’s why getting to 450 ppm is not yet politically possible. Not even close.
Three more points: First, it bears repeating that the wedges are not analytically rigorous (as I explained in Part 1), but they are conceptually useful. We might need a couple more or a couple less.
Second, some people, like our friend Roger Pielke, Jr., mistakenly think we need a lot more wedges. I explain where he is wrong in Part 2.5: The fuzzy math of the stabilization wedges [warning: only for hard-core wonks].
Third, if you don’t like one of those wedges, you need to find a replacement strategy. Other possibilities can be found here, but I think the ones above are the most plausible by far, which tells you how dubious some of Princeton’s other wedges are [– I’m talking about you, would-be hydrogen wedges].
Could a bunch of breakthrough technologies substitute for some of the above wedges? That is far, far more implausible, as I will discuss next week (or see here).
- Is 450 ppm (or less) politically possible? Part 7: The harsh lessons of the financial bailout
- Is 450 ppm politically possible? Part 6: What the Boxer-Lieberman-Warner bill debate tells us
- Is 450 ppm possible? Part 5: Old coal’s out, can’t wait for new nukes, so what do we do NOW?
- Is 450 ppm politically possible? Part 4: The most urgent climate policy (and it isn’t a CO2 price)