This is freedom?

From the CSM on the Gates arrest:

“The rule is, if a police officer stops you in a car or on the street, he’s the captain of the ship, and whatever he says goes,” says Jim Pasco, executive director of the Fraternal Order of Police’s legislative division. “If you’ve got something to address, do it later. Do what he says, or else only bad things can happen.”

I think I see where this guy’s coming from, but it really sounds bad. If an officer asks me to stop doing something constitutionally protected (say, taking pictures), I can’t argue the case on the spot? I either give up my rights or go downtown?

Unprincipled Forecast Evaluation

I hadn’t noticed until I heard it here, but Armstrong & Green are back at it, with various claims that climate forecasts are worthless. In the Financial Post, they criticize the MIT Joint Program model,

… No more than 30% of forecasting principles were properly applied by the MIT modellers and 49 principles were violated. For an important problem such as this, we do not think it is defensible to violate a single principle.

As I wrote in some detail here, the Forecasting Principles are a useful seat-of-the-pants guide to good practices, but there’s no evidence that following them all is necessary or sufficient for a good outcome. Some are likely to be counterproductive in many situations, and key elements of good modeling practice are missing (for example, balancing units of measure).

It’s not clear to me that A&G really understand models and modeling. They seem to view everything through the lens of purely statistical methods like linear regression. Green recently wrote,

Another important principle is that the forecasting method should provide a realistic representation of the situation (Principle 7.2). An interesting statement in the MIT report that implies (as one would expect given the state of knowledge and omitted relationships) that the modelers have no idea to what extent their models provide a realistic representation of reality is as follows:

‘Changes in global surface average temperature result from a combination of emissions and climate parameters, and therefore two runs that look similar in terms of temperature may be very different in detail.’ (MIT Report p. 28)

While the modelers have sufficient latitude in their parameters to crudely reproduce a brief period of climate history, there is no reason to believe the models can provide useful forecasts.

What the MIT authors are saying, in essence, is that

T = f(E,P)

and that it is possible to achieve the same future temperature T with different combinations of emissions E and parameters P. Green seems to be taking a leap, to assume that historic T does not provide much constraint on P. First, that’s not necessarily true, given that historic E cannot be chosen freely. It could still be the case that the structure of f(E,P) means that historic T provides a weak constraint on P given E. But if that’s true (as it basically is), the problem is self-diagnosing: estimates of P will have broad confidence bounds, as will forecasts of T. Green completely ignores the MIT authors’ explicit characterization of this uncertainty. He also ignores the fact that the output of the model is not just T, and that we have priors for many elements of P (from more granular models or experiments, for example). Thus we have additional lines of evidence with which to constrain forecasts. Green also neglects to consider the implications of uncertainties in P that are jointly distributed in an offsetting manner (as is likely for climate sensitivity, ocean circulation, and aerosol forcing).

A&G provide no formal method to distinguish between situations in which models yield useful or spurious forecasts. In an earlier paper, they claimed rather broadly,

‘To our knowledge, there is no empirical evidence to suggest that presenting opinions in mathematical terms rather than in words will contribute to forecast accuracy.’ (page 1002)

This statement may be true in some settings, but obviously not in general. There are many situations in which mathematical models have good predictive power and outperform informal judgments by a wide margin.

A&G’s latest paper with Willie Soon, Validity of Climate Change Forecasting for Public Policy Decision Making, apparently forthcoming in IJF, is an attempt to make the distinction, i.e. to determine whether climate models have any utility as predictive tools. An excerpt from the abstract summarizes their argument:

Policymakers need to know whether prediction is possible and if so whether any proposed forecasting method will provide forecasts that are substantively more accurate than those from the relevant benchmark method. Inspection of global temperature data suggests that it is subject to irregular variations on all relevant time scales and that variations during the late 1900s were not unusual. In such a situation, a ‘no change’ extrapolation is an appropriate benchmark forecasting method. … The accuracy of forecasts from the benchmark is such that even perfect forecasts would be unlikely to help policymakers. … We nevertheless demonstrate the use of benchmarking with the example of the Intergovernmental Panel on Climate Change’s 1992 linear projection of long-term warming at a rate of 0.03°C-per-year. The small sample of errors from ex ante projections at 0.03°C-per-year for 1992 through 2008 was practically indistinguishable from the benchmark errors. … Again using the IPCC warming rate for our demonstration, we projected the rate successively over a period analogous to that envisaged in their scenario of exponential CO2 growth’”the years 1851 to 1975. The errors from the projections were more than seven times greater than the errors from the benchmark method. Relative errors were larger for longer forecast horizons. Our validation exercise illustrates the importance of determining whether it is possible to obtain forecasts that are more useful than those from a simple benchmark before making expensive policy decisions.

There are many things wrong here:

  1. Demonstrating that unforced variability (history) can be adequately forecasted by a naive benchmark has no bearing on whether future forced variability will continue to be well-represented, or whether models can predict future emergence of a signal from noise. AG&S’ procedure is like watching an airplane taxi, concluding that aerodynamics knowledge is of no advantage, and predicting that the plane will remain on the ground forever.
  2. Comparing a naive forecast for global mean temperature against models amounts to a rejection of a vast amount of information. What is the naive forecast for the joint behavior of temperature, preciptiation, lapse rates, sea level, and their spatial and seasonal patterns? These have been evaluated for models, but AG&S do not suggest benchmarks.
  3. A no-change forecast is not necessarily the best naive forecast for a series with unknown variability, if that series has some momentum or structure which can be exploited to do better. The particular no change forecast selected byAG&S is suboptimal, because it uses a single year as a forecast, unneccesarily projecting annual variation into the future. In general, a stronger naive forecast (e.g., a smoothed value of a few recent years) would strengthen AG&S’ case, so it’s unclear why they’ve chosen an excessively naive benchmark. Fortunately, their base year, 1991, was rather “average”.
  4. The first exhibit presented is the EPICA ice core temperature. Roughly 85% of the data shown has a time interval too long to show century-scale temperature variations, and none of it could be expected to fully reveal decadal-scale variations, so it’s mostly irrelevant with respect to the kind of forecasts they seek to evaluate.
  5. The mere fact that a series has unknown historic variability does not mean that it cannot be forecast [corrected 8/18/09]. The EPICA and Vostok CO2 records look qualitatively much like the temperature record, yet CO2 accumulation in the atmosphere is quite predictable over decadal time scales, and models could handily beat a naive forecast.
  6. AG&S’ method of forecast evaluation unduly weights the short term, like the A&G sucker bet does. This is not strictly a problem, but it does make interpretation of the bounds on AG&S’ alternate forecast (“The benchmark forecast is that the global mean temperature for each year for the rest of this century will be within 0.5°C of the 2008 figure.”) a little tricky.
  7. The retrospective evaluation of the 1990/1992 IPCC projection of 0.3C/decade ignores many factors. First, 0.3C/decade over a century does not imply a smooth trend over short time scales; models and reality have substantial unforced variability which must be taken into account. The paragraph cited by AG&S includes the statement, “The rise will not be steady because of the influence of other factors.” Second, the 1992 report (in the very paragraph AG&S cite) notes that projections do not account for aerosols, so 0.3C/decade can’t be taken as a point prediction for the future, even if contingency on GHG emissions is resolved. Third, the IPCC projection stated approximate bounds – 0.2 to 0.5 C/decade – that should be accounted for in the evaluation, but are not. Still, the IPCC projection beats the naive benchmark.
  8. AG&S’ evaluation of the 0.3C/decade future BAU projection as a backcast over 1851-1975 is absurd. They write, “It is not unreasonable, then, to suppose for the purposes of our validation illustration that scientists in 1850 had noticed that the increasing industrialization of the world was resulting in exponential growth in ‘greenhouse gases’ and to project that this would lead to global warming of 0.03°C per year.” Actually, it’s completely unreasonable. Many figures in the 1990 FAR clearly indicate that the 0.3C/decade projection was not valid on [-infinity,infinity]. For example, figures 6, 8, and 9 from the SPM – just a few pages from material cited by AG&S – clearly show a gentle trend <0.05C/decade through 1950. Furthermore, even the most rudimentary understanding of the dynamics of GHG and heat accumulation is sufficient to realize that one would not expect a linear historic temperature trend to emerge from the emissions signal.

How do AG&S arrive at this sorry state? Their article embodies a “sh!t happens” epistemology. They write, “The belief that ‘things have changed’ and the future cannot be judged by the past is common, but invalid.” The problem is, one can say with equal confidence that, “the belief that ‘things never change’ and the past reveals the future is common, but invalid.” In reality, there are predictable phenomena (the orbits of the planets) and unpredictable ones (the fall of the Berlin wall). AG&S have failed to establish that climate is unpredictable or to provide us with an appropriate method for deciding whether it is predictable or not. Nor have they given us any insight into how to know or what to do if we can’t decide. Doing nothing because we think we don’t know anything is probably better than sacrificing virgins to the gods, but it doesn’t strike me as a robust strategy.

Bolivia Barking

I recently wondered whether developing countries were asking for the wrong thing in Bonn. Now Bolivia is barking up the right tree with a proposed “climate debt” concept. The idea’s actually quite old; it’s already well developed in the Greenhouse Development Rights framework.

The trick is, how to achieve an equitable outcome that’s consistent with the physics of climate? Consider this reaction to ideas like climate debt:

Obama’s Global Tax

By INVESTOR’S BUSINESS DAILY | Posted Tuesday, July 29, 2008 4:20 PM PT

Election ’08: A plan by Barack Obama to redistribute American wealth on a global level is moving forward in the Senate. It follows Marxist theology – from each according to his ability, to each according to his need.

Obama would give them all a fish without teaching them how to fish. Pledging to cut global poverty in half on the backs of U.S. taxpayers is a ridiculous and impossible goal.

We already transfer too much national wealth to the United Nations and its busybody agencies. …

If you’re worried abut gasoline and heating oil prices now, think what they’ll be like when the U.S. is subjected in an Obama administration to global energy consumption and production taxes. Obama’s Global Poverty Act is the “international community’s” foot in the door.

Obama has called on the U.S. to “lead by example” on global warming and probably would submit to a Kyoto-like agreement that would sock Americans with literally trillions of dollars in costs over the next half century for little or no benefit.

“We can’t drive our SUVs and eat as much as we want and keep our homes on 72 degrees at all times . . . and then just expect that other countries are going to say OK,” Obama has said. “That’s not leadership. That’s not going to happen.”

Oh, really? Who’s to say we can’t load up our SUV and head out in search of bacon double cheeseburgers at the mall? China? India? Bangladesh? The U.N.?

I suspect that these sentiments are quite prevalent, at least in the US. I’m even sympathetic in at least one respect: transfers from the global rich to poor are beneficial in principle, but difficult to execute. Transfers from country to country are susceptible to capture by elites. Direct transfers among individuals could be facilitated by a global carbon market with allowances allocated to individuals (one of the few good arguments for emissions trading in my mind), but would undemocratic regimes permit their citizens to participate?

I don’t see agreement on this front any time soon. I could see things going a different way: the US, EU and a few other developed nations move to reduce, then goad developing nations along with a mixture of carrot (offset projects and other transfers) and stick (border carbon adjustments).

Dynamic Drinking

Via ScienceDaily,

A large body of social science research has established that students tend to overestimate the amount of alcohol that their peers consume. This overestimation causes many to have misguided views about whether their own behaviour is normal and may contribute to the 1.8 million alcohol related deaths every year. Social norms interventions that provide feedback about own and peer drinking behaviours may help to address these misconceptions.

Erling Moxnes has looked at this problem from a dynamic perspective, in Moxnes, E. and L. C. Jensen (in press). “Drunker than intended; misperceptions and information treatments.” Drug and Alcohol Dependence. From an earlier Athens SD conference paper,

Overshooting alcohol intoxication, an experimental study of one cause and two cures

Juveniles becoming overly intoxicated by alcohol is a widespread problem with consequences ranging from hangovers to deaths. Information campaigns to reduce this problem have not been very successful. Here we use a laboratory experiment with high school students to test the hypothesis that overshooting intoxication can follow from a misperception of the delay in alcohol absorption caused by the stomach. Using simulators with a short and a long delay, we find that the longer delay causes a severe overshoot in the blood alcohol concentration. Behaviour is well explained by a simple feedback strategy. Verbal information about the delay does not lead to a significant reduction of the overshoot, while a pre test mouse-simulator experience removes the overshoot. The latter policy helps juveniles lessen undesired consequences of drinking while preserving the perceived positive effects. The next step should be an investigation of simulator experience on real drinking behaviour.

Washboard Evolution

Via ScienceDaily,

Just about any road with a loose surface ’” sand or gravel or snow ’” develops ripples that make driving a very shaky experience. A team of physicists from Canada, France and the United Kingdom have recreated this “washboard” phenomenon in the lab with surprising results: ripples appear even when the springy suspension of the car and the rolling shape of the wheel are eliminated. The discovery may smooth the way to designing improved suspension systems that eliminate the bumpy ride.

“The hopping of the wheel over the ripples turns out to be mathematically similar to skipping a stone over water,” says University of Toronto physicist, Stephen Morris, a member of the research team.

“To understand the washboard road effect, we tried to find the simplest instance of it, he explains. We built lab experiments in which we replaced the wheel with a suspension rolling over a road with a simple inclined plow blade, without any spring or suspension, dragging over a bed of dry sand. Ripples appear when the plow moves above a certain threshold speed.”

“We analyzed this threshold speed theoretically and found a connection to the physics of stone skipping. A skipping stone needs to go above a specific speed in order to develop enough force to be thrown off the surface of the water. A washboarding plow is quite similar; the main difference is that the sandy surface “remembers” its shape on later passes of the blade, amplifying the effect.”

Strategic Excess? Breakthrough's Nightmare?

Since it was the Breakthrough analysis that got me started on this topic, I took a quick look at it again. Their basic objection is:

Therein lies a Catch-22 of ACES: if the annual use of up to 2 billion tons of offsets permitted by the bill is limited due to a restricted supply of affordable offsets, the government will pick up the slack by selling reserve allowances, and “refill” the reserve pool with international forestry offset allowances later. […]

The strategic allowance reserve would be established by taking a certain percentage of allowances originally reserved for the future — 1% of 2012-2019 allowances, 2% of 2020-2029 allowances, and 3% of 2030-2050 allowances — for a total size of 2.7 billion allowances. Every year throughout the cap and trade program, a certain portion of this reserve account would be available for purchase by polluters as a “safety valve” in case the price of emission allowances rises too high.

How much of the reserve account would be available for purchase, and for what price? The bill defines the reserve auction limit as 5 percent of total emissions allowances allocated for any given year between 2012-2016, and 10 percent thereafter, for a total of 12 billion cumulative allowances. For example, the bill specifies that 5.38 billion allowances are to be allocated in 2017 for “capped” sectors of the economy, which means 538 million reserve allowances could be auctioned in that year (10% of 5.38 billion). In other words, the emissions “cap” could be raised by 10% in any year after 2016.

First, it’s not clear to me that international offset supply for refilling the reserve is unlimited. Section 726 doesn’t say they’re unlimited, and a global limit of 1 to 1.5 GtCO2eq/yr applies elsewhere. Anyhow, given the current scale of the offset market, it’s likely that reserve refilling will be competing with market participants for a limited supply of allowances.

Second, even if offset refills do raise the de facto cap, that doesn’t raise global emissions, except to the extent that offsets aren’t real, additional and all that. With perfect offsets, global emissions would go down due to the 5:4 exchange ratio of offsets for allowances. If offsets are really rip-offsets, then W-M has bigger problems than the strategic reserve refill.

Third, and most importantly, the problem isn’t oversupply of allowances through the reserve. Instead, it’s hard to get allowances out of the reserve – they check in, and never check out. Simple math suggests, and simulations confirm, that it’s hard to generate a price trajectory yielding sustained auction release. Here’s a test with 3%/yr BAU emissions growth and 10% underlying demand volatility:


Even with these implausibly high drivers, it’s hard to get a price trajectory that triggers a sustained auction flow, and total allowance supply (green) and emissions hardly differ from from the no-reserve case.

My preliminary simulation experiments suggest that it’s very unlikely that Breakthrough’s nightmare, a 10% cap violation, could really occur. To make that happen overall, you’d need sustained price increases of over 20% per year – i.e., an allowance price of $56,000/TonCO2eq in 2050. However, there are lesser nightmares hidden in the convoluted language – a messy program to administer, that in the end fails to mitigate volatility.

Strategic Excess? Insights

Model in hand, I tried some experiments (actually I built the model iteratively, while experimenting, but it’s hard to write that way, so I’m retracing my steps).

First, the “general equilbrium equivalent” version: no volatility, no SR marginal cost penalty for surprise, and firms see the policy coming. Result: smooth price escalation, and the strategic reserve is never triggered. Allowances just pile up in the reserve:



Since allowances accumulate, the de facto cap is 1-3% lower (by the share of allowances allocated to the reserve).

If there’s noise (SD=4.4%, comparable to petroleum demand), imperfect foresight, and short run adjustment costs, the market is more volatile:


However, something strange happens. The stock of reserve allowances actually increases, even though some reserves are auctioned intermittently. That’s due to the refilling mechanism. An early auction, plus overreaction by firms, triggers a near-collapse in allowance prices (as happened in the ETS). Thus revenues generated in the reserve auction at high prices used to buy a lot of forestry offsets at very low prices:


Could this happen in reality? I’m not sure – it depends on timing, behavior, and details of the recycling implementation. I think it’s safe to say that the current design is not robust to such phenomena. Fortunately, the market impact over the long haul is not great, because the extra accumulated allowances don’t get used (they pile up, as in the smooth case).

So, what is the reserve really accomplishing? Not much, it seems. Here’s the same trajectory, with volatility but no strategic reserve system:


The mean price with the reserve (blue) is actually slightly higher, because the reserve mainly squirrels away allowances, without ever releasing them. Volatility is qualitatively the same, if not worse. That doesn’t seem like a good trade (unless you like the de facto emissions cut, which could be achieved more easily by lowering the cap and scrapping the reserve mechanism).

One reason the reserve fails to achieve its objectives is the recycling mechanism, which creates a perverse feedback loop that offsets the strategic reserve’s intended effect:


The intent of the reserve is to add a balancing feedback loop (B2, green) that stabilizes price. The problem is, the recycling mechanism (R2, red) consumes international forestry offsets that would otherwise be available for compliance, thus working against normal market operations (B2, blue). Thus the mechanism is only helpful to the extent that it exploits clever timing (doubtful), has access to offsets unavailable to the broad market (also doubtful), or doesn’t recycle revenue to refill the reserve. If you have a reserve, but don’t refill, you get some benefit:


Still, the reserve mechanism seems like a lot of complexity yielding little benefit. At best, it can iron out some wrinkles, but it does nothing about strong, sustained price excursions (due to picking an infeasible target, for example). Perhaps there is some other design that could perform better, by releasing and refilling the reserve in a more balanced fashion. That ideal starts to sound like “buy low, sell high” – which is what speculators in the market are supposed to do. So, again, why bother?

I suspect that a more likely candidate for stabilization, robust to uncertainty, involves some possible violation of the absolute cap (gasp!). Realistically, if there are sustained price excursions, congress will violate it for us, so perhaps its better to recognize that up front and codify some orderly process for adaptation. At the least, I think congress should scrap the current reserve, and write the legislation in such a way as to kick the design problem to EPA, subject to a few general goals. That way, at least there’d be time to think about the design properly.

Strategic Excess? The Model

It’s hard to get an intuitive grasp on the strategic reserve design, so I built a model (which I’m not posting because it’s still rather crude, but will describe in some detail). First, I’ll point out that the model has to be behavioral, dynamic, and stochastic. The whole point of the strategic reserve is to iron out problems that surface due to surprises or the cumulative effects of agent misperceptions of the allowance market. You’re not going to get a lot of insight about this kind of situation from a CGE or intertemporal optimization model – which is troubling because all the W-M analysis I’ve seen uses equilibrium tools. That means that the strategic reserve design is either intuitive or based on some well-hidden analysis.

Here’s one version of my sketch of market operations (click to enlarge):
Strategic reserve structure

It’s already complicated, but actually less complicated than the mechanism described in W-M. For one thing, I’ve made some process continuous (compliance on a rolling basis, rather than at intervals) that sound like they will be discrete in the real implementation.

The strategic reserve is basically a pool of allowances withheld from the market, until need arises, at which point they are auctioned and become part of the active allowance pool, usable for compliance:


Reserves auctioned are – to some extent – replaced by recycling of the auction revenue:


Refilling the strategic reserve consumes international forestry offsets, which may also be consumed by firms for compliance. Offsets are created by entrepreneurs, with supply dependent on market price.


Auctions are triggered when market prices exceed a threshold, set according to smoothed actual prices:


(Actually I should have labeled this Maximum, not Minimum, since it’s a ceiling, not a floor.)

The compliance market is a bit complicated. Basically, there’s an aggregate firm that emits, and consumes offsets or allowances to cover its compliance obligation for those emissions (non-compliance is also possible, but doesn’t occur in practice; presumably W-M specifies a penalty). The firm plans its emissions to conform to the expected supply of allowances. The market price emerges from the marginal cost of compliance, which has long run and short run components. The LR component is based on eyeballing the MAC curve in the EPA W-M analysis. The SR component is arbitrarily 10x that, i.e. short term compliance surprises are 10x as costly (or the SR elasticity is 10x lower). Unconstrained firms would emit at a BAU level which is driven by a trend plus pink noise (the latter presumably originating from the business cyle, seasonality, etc.).


So far, so good. Next up: experiments.

Strategic Excess? Simple Math

Before digging into a model, I pondered the reserve mechanism a bit. The idea of the reserve is to provide cost containment. The legislation sets a price trigger at 60% above a 36-month moving average of allowance trade prices. When the current allowance price hits the trigger level, allowances held in the reserve are sold quarterly, subject to an upper limit of 5% to 20% of current-year allowance issuance.

To hit the +60% trigger point, the current price would have to rise above the average through some combination of volatility and an underlying trend. If there’s no volatility, the the trigger point permits a very strong trend. If the moving average were a simple exponential smooth, the basis for the trigger would follow the market price with a 36-month lag. That means the trigger would be hit when 60% = (growth rate)*(3 years), i.e. the market price would have to grow 20% per year to trigger an auction. In fact, the moving average is a simple average over a window, which follows an exponential input more closely, so the effective lag is only 1.5 years, and thus the trigger mechanism would permit 40%/year price increases. If you accept that the appropriate time trajectory of prices is more like an increase at the interest rate, it seems that the strategic reserve is fairly useless for suppressing any strong underlying exponential signal.

That leaves volatility. If we suppose that the underlying rate of increase of prices is 10%/year, then the standard deviation of the market price would have to be (60%-(10%/yr*1.5yr))/2 = 22.5% in order to trigger the reserve. That’s not out of line with the volatility of many commodities, but it seems like a heck of a lot of volatility to tolerate when there’s no reason to. Climate damages are almost invariant to whether a ton gets emitted today or next month, so any departure from a smooth price trajectory imposes needless costs (but perhaps worthwhile if cap & trade is really the only way to get a climate policy in place).

The volatility of allowance prices can be translated to a volatility of allowance demand by assuming an elasticity of allowance demand. If elasticity is -0.1 (comparable to short run gasoline estimates), then the underlying demand volatility would be 2.25%. The actual volatility of weekly petroleum consumption around a 1 quarter average is just about twice that:

Weekly petroleum products supplied

So, theoretically the reserve might shave some of these peaks, but one would hope that the carbon market wouldn’t be transmitting this kind of noise in the first place.

Strategic Excess?

I’ve been reading the Breakthrough Institute’s Waxman Markey analysis, which is a bit spotty* but raises many interesting issues. One comment seemed too crazy to be true: that the W-M strategic reserve is “refilled” with forestry offsets. Sure enough, it is true:

726 (g) (2) INTERNATIONAL OFFSET CREDITS FOR REDUCED DEFORESTATION- The Administrator shall use the proceeds from each strategic reserve auction to purchase international offset credits issued for reduced deforestation activities pursuant to section 743(e). The Administrator shall retire those international offset credits and establish a number of emission allowances equal to 80 percent of the number of international offset credits so retired. Emission allowances established under this paragraph shall be in addition to those established under section 721(a).

This provision makes the reserve nearly self-perpetuating: at constant prices, 80% of allowances released from the reserve are replaced. If the reserve accomplishes its own goal of reducing prices, more than 80% get replaced (if replacement exceeds 100%, the excess is vintaged and assigned to future years). This got me wondering: does anyone understand how the reserve really works? Its market rules seem arbitrary. Thus I set out to simulate them.

First, I took a look at some data. What would happen if the reserve strategy were applied to other commodities? Here’s oil:

Oil prices & moving average cap

Red is the actual US weekly crude price, while purple shows the strategic reserve price trigger level: a 3-year moving average + 60%. With this trajectory, the reserve would be shaving a few peaks, but wouldn’t do anything about the long term runup in prices. Same goes for corn: Continue reading “Strategic Excess?”