Category: Climate

Sea Level Rise Models – I

A recent post by Stefan Rahmstorf at RealClimate discusses a new paper on sea level projections by Grinsted, Moore and Jevrejeva. This paper comes at an interesting time, because we’ve just been discussing sea level projections in the context of our ongoing science review of the C-ROADS model. In C-ROADS, we used Rahmstorf’s earlier semi-empirical model, which yields higher sea level rise than AR4 WG1 (the latter leaves out ice sheet dynamics). To get a better handle on the two papers, I compared a replication of the Rahmstorf model (from John Sterman, implemented in C-ROADS) with an extension to capture Grinsted et al. This post (in a few parts) serves as both an assessment of the models and a bit of a tutorial on data analysis with Vensim.

My primary goal here is to develop an opinion on four questions:

  • Can the conclusions be rejected, given the data?
  • Is the Grinsted et al. argument from first principles, that the current sea level response is dominated by short time constants, reasonable?
  • Is Rahmstorf right to assert that Grinsted et al.’s determination of the sea level rise time constant is shaky?
  • What happens if you impose the long-horizon paleo constraint to equilibrium sea level rise in Rahmstorf’s RC figure on the Grinsted et al. model?

Paleo constraints on equilibrium sea level

Continue reading “Sea Level Rise Models – I”

What We Need

In Four Legs and a Tail I pondered what we need to get some action on climate. Over the holidays I heard Seamus Heaney on NPR. A story from his Nobel lecture came up, which I think rather poignantly illustrates the nature of the needed paradigm shift, in a different context:

One of the most harrowing moments in the whole history of the harrowing of the heart in Northern Ireland came when a minibus full of workers being driven home one January evening in 1976 was held up by armed and masked men and the occupants of the van ordered at gunpoint to line up at the side of the road. Then one of the masked executioners said to them, “Any Catholics among you, step out here”. As it happened, this particular group, with one exception, were all Protestants, so the presumption must have been that the masked men were Protestant paramilitaries about to carry out a tit-for-tat sectarian killing of the Catholic as the odd man out, the one who would have been presumed to be in sympathy with the IRA and all its actions. It was a terrible moment for him, caught between dread and witness, but he did make a motion to step forward. Then, the story goes, in that split second of decision, and in the relative cover of the winter evening darkness, he felt the hand of the Protestant worker next to him take his hand and squeeze it in a signal that said no, don’t move, we’ll not betray you, nobody need know what faith or party you belong to. All in vain, however, for the man stepped out of the line; but instead of finding a gun at his temple, he was thrown backward and away as the gunmen opened fire on those remaining in the line, for these were not Protestant terrorists, but members, presumably, of the Provisional IRA.

It is difficult at times to repress the thought that history is about as instructive as an abattoir; that Tacitus was right and that peace is merely the desolation left behind after the decisive operations of merciless power. I remember, for example, shocking myself with a thought I had about that friend who was imprisoned in the seventies upon suspicion of having been involved with a political murder: I shocked myself by thinking that even if he were guilty, he might still perhaps be helping the future to be born, breaking the repressive forms and liberating new potential in the only way that worked, that is to say the violent way – which therefore became, by extension, the right way. It was like a moment of exposure to interstellar cold, a reminder of the scary element, both inner and outer, in which human beings must envisage and conduct their lives. But it was only a moment. The birth of the future we desire is surely in the contraction which that terrified Catholic felt on the roadside when another hand gripped his hand, not in the gunfire that followed, so absolute and so desolate, if also so much a part of the music of what happens.

(Emphasis added)

Four Legs and a Tail

An effective climate policy needs prices, technology, institutional rules, and preferences.

I’m continuously irked by calls for R&D to save us from climate change. Yes, we need it very badly, but it’s no panacea. Without other signals, like a price on carbon, technology isn’t going to do a lot. It’s a one-legged dog. True, we might get lucky with some magic bullet, but I’m not willing to count on that. An effective climate policy needs four legs:

  1. Prices
  2. Technology (the landscape of possibilities on which we make decisions)
  3. Institutional rules and procedures
  4. Preferences, operating within social networks

Continue reading “Four Legs and a Tail”

News Flash: There Is No "Environmental Certainty"

The principal benefit cited for cap & trade is “environmental certainty,” meaning that “a cap-and-trade system, coupled with adequate enforcement, assures that environmental goals actually would be achieved by a certain date.” Environmental certainty is a bit of a misnomer. I think of environmental certainty as ensuring a reasonable chance of avoiding serious climate impacts. What people mean when they’re talking about cap & trade is really “emissions certainty.” Unfortunately, emissions certainty doesn’t provide climate certainty:

Emissions trajectories yielding 2C temperature change

Even if we could determine a “safe” level of interference in the climate system, the sensitivity of global mean temperature to increasing atmospheric CO2 is known perhaps only to a factor of three or less. Here we show how a factor of three uncertainty in climate sensitivity introduces even greater uncertainty in allowable increases in atmospheric CO2 CO2 emissions. (Caldeira, Jain & Hoffert, Science)

The uncertainty about climate sensitivity (not to mention carbon cycle feedbacks and other tipping point phenomena) makes the emissions trajectory we need highly uncertain. That trajectory is also subject to other big uncertainties – technology, growth convergence, peak oil, etc. Together, those features make it silly to expend a lot of effort on detailed plans for 2050. We don’t need a ballistic trajectory; we need a guidance system. I’d like to see us agree to a price on GHGs everywhere now, along with a decision rule for adapting that price over time until we’re on a downward emissions trajectory. Then move on to the other legs of the stool: ensuring equitable opportunities for development, changing lifestyle, tackling institutional barriers to change, and investing in technology.

Unfortunately, cap & trade seems ill-suited to adaptive control. Emissions commitments and allowance allocations are set in multi-year intervals, announced in advance, with long lead times for design. Financial markets and industry players want that certainty, but the delay limits responsiveness. Decision makers don’t set the commitment by strictly environmental standards; they also ask themselves what allocation will result in an “acceptable” price. They’re risk averse, so they choose an allocation that’s very likely to lead to an acceptable price. That means that, more often than not, the system will be overallocated. On balance, their conservatism is probably a good thing; otherwise the whole system could unravel from a negative public reaction to volatile prices. Ironically, safety valves – one policy that could make cap & trade more robust, and thus enable better mean performance – are often opposed because they reduce emissions certainty.

Cap & Trade – How Soon?

I’m a strong advocate for a price on carbon, but I have serious reservations about cap & trade. I’m thrilled that climate policy is finally getting off the dime, but I wish enthusiasm were focused on a carbon tax instead. Consider this:

Jurisdiction Instrument Started Operational Status
EU Cap & Trade 2003 2005 Phase 1 overallocated & underpriced; still wrangling over loopholes for subsequent phases
British Columbia Tax Feb 2008 July 2008 Too low to do much yet, but working
Sweden Tax 1991 1991 Running, at $150/TonCO2; emissions down
RGGI Cap & Trade 2003 2008 Overallocated
Norway Tax 1990 1991 Works; not enough to lower emissions substantially
California Cap & Trade (part of AB32) 2007 Earliest 2012 Punted
WCI Cap & Trade 2007 Earliest 2012 Draft design

The pattern that stands out to me is timing – cap & trade systems are slow to get out of the gate compared to carbon taxes. They entail huge design challenges, which often restrict sectoral coverage. Price uncertainty makes it difficult to work out the implications of allowance allocation (unless you go to pure auction, in which case you lose the benefit of transitional grandfathering as a mechanism to buy carbon-intensive industry participation). I think we’ll be lucky to see an operational cap & trade system in the US, with meaningful prices and broad coverage, by the end of the first Obama administration.

Next Generation Climate Policy Models

Today I’m presenting a talk at an ECF workshop, Towards the next generation of climate policy models. The workshop’s in Berlin, but I’m staying in Montana, so my carbon footprint is minimal for this one (just wait until next month …). My slides are here: Towards Next Generation Climate Policy Models.

I created a set of links to supporting materials on del.icio.us.

Update Workshop materials are now on a web site here.

California Punting on Cap & Trade

Bloomberg reports that California’s cap and trade program may still be some way off:

[CARB chair] Nichols told venture capitalists and clean-energy executives last week in Mountain View, California, that she was “thinking of punting,” saying the specifics of the emissions-trading program may not be ready for 1-2 more years.

“I think the cap-and-trade system needs to be thought through and I don’t think that has been done yet,” said Jerry Hill, a member of the Air Resources Board. “It would be a good idea to take our time to be sure what we do create is successful.”

Greentech VCs aren’t thrilled, but I think this is wise, and applaud CARB for recognizing the scale of the design task rather than launching a half-baked program. Still, delay is costly, and design complexity contributes to delay. California has a lot of balls in the air, with a hybrid design involving a dozen or so sectoral initiatives, a low-carbon fuel standard, and cap & trade. As I said a while ago,

My fear is that the analysis of GHG initiatives will ultimately prove overconstrained and underpowered, and that as a result implementation will ultimately crumble when called upon to make real changes (like California’s ambitious executive order targeting 2050 emissions 80% below 1990 levels). California’s electric power market restructuring debacle jumps to mind. I think underpowered analysis is partly a function of history. Other programs, like emissions markets for SOx, energy efficiency programs, and local regulation of criteria air pollutants have all worked OK in the past. However, these activities have all been marginal, in the sense that they affect only a small fraction of energy costs and a tinier fraction of GDP. Thus they had limited potential to create noticeable unwanted side effects that might lead to damaging economic ripple effects or the undoing of the policy. Given that, it was feasible to proceed by cautious experimentation. Greenhouse gas regulation, if it is to meet ambitious goals, will not be marginal; it will be pervasive and obvious. Analysis budgets of a few million dollars (much less in most regions) seem out of proportion with the multibillion $/year scale of the problem.

One result of the omission of a true top-down design process is that there has been no serious comparison of proposed emissions trading schemes with carbon taxes, though there are many strong substantive arguments in favor of the latter. In California, for example, the CPUC Interim Opinion on Greenhouse Gas Regulatory Strategies states, ‘We did not seriously consider the carbon tax option in the course of this proceeding, due to the fact that, if such a policy were implemented, it would most likely be imposed on the economy as a whole by ARB.’ It’s hard for CARB to consider a tax, because legislation does not authorize it. It’s hard for legislators to enable a tax, because a supermajority is required and it’s generally considered poor form to say the word ‘tax’ out loud. Thus, for better or for worse, a major option is foreclosed at the outset.

At the risk of repeating myself,

The BC tax demonstrates a huge advantage of a carbon tax over cap & trade: it can be implemented quickly. The tax was introduced in the Feb. 19 budget, and switched on July 1st. By contrast, the WCI and California cap & trade systems have been underway much longer, and still are no where near going live.

My preferred approach to GHG regulation would be, in a nutshell: (a) get a price on emissions ASAP, in as simple and stable a way as possible; if you can’t have a tax, design cap & trade to look like a tax (b) get other regions to harmonize (c) then do all that other stuff: removing institutional barriers to change, R&D, efficiency and renewable incentives, in roughly that order (c) dispense with portfolio standards and other mandates unless (a) through (c) aren’t doing the job.