Under French President Nicolas Sarkozy’s leadership, the G-20 has made addressing food-price volatility a top priority this year, with member states’ agriculture ministers meeting recently in Paris to come up with solutions. The choice of priorities has turned out to be timely: world food prices reached a record high earlier in 2011, recalling a similar price spike in 2008.

Consumers are hurting worldwide, especially the poor, for whom food takes a major bite out of household budgets. Popular discontent over food prices has fueled political instability in some countries, most notably in Egypt and Tunisia. Even agricultural producers would prefer some price stability over the wild ups and downs of the last five years.

The G-20’s efforts will culminate in the Cannes Summit in November. But, when it comes to specific policies, caution will be very much in order, for there is a long history of measures aimed at reducing commodity-price volatility that have ended up doing more harm than good.

For example, some inflation-targeting central banks have reacted to increases in prices of imported commodities by tightening monetary policy and thereby increasing the value of the currency. But adverse movements in the terms of trade must be accommodated; they cannot be fought with monetary policy.

Producing countries have also tried to contain price volatility by forming international cartels. But these have seldom worked.  

In theory, government stockpiles might be able to smooth price fluctuations, releasing commodities in times of shortage and adding to stocks when prices are low.   A free-marketer will point out that they can undermine the incentive for the private sector to hold stockpiles.  A valid response is that this incentive is undermined regardless, because political economy never allows “hoarders” to “price gouge” in times of food crisis.    It all depends on how stockpiles are administered.  The record in practice is not encouraging.

In rich countries, where the primary producing sector usually has political power, stockpiles of food products are used as a means of keeping prices high rather than low. The European Union’s Common Agricultural Policy is a classic example – and has been disastrous for EU budgets, economic efficiency, and consumer pocketbooks.

In many developing countries, on the other hand, farmers lack political power.  Some African countries adopted commodity boards for coffee and cocoa at the time of independence. Although the original rationale was to buy the crop in years of excess supply and sell in years of excess demand, thereby stabilizing prices, in practice the price paid to cocoa and coffee farmers, who were politically weak, was always below the world price.  In response, production fell.

Politicians often seek to shield consumers through price controls on staple foods and energy.  But the artificially suppressed price usually requires rationing to domestic households. (Shortages and long lines can fuel political rage as well as higher prices can.). Otherwise, the policy can require increased imports in order to satisfy the excess demand, and so can raise the world price even more.

If the country is a producer of the commodity in question, it may use export controls  to insulate domestic consumers from increases in the world price. In 2008, India capped rice exports, and Argentina did the same for wheat exports, as did Russia in 2010.

Export restrictions in producing countries and price controls in importing countries both serve to exacerbate the magnitude of the world price upswing, owing to the artificially reduced quantity that is still internationally traded. If producing and consuming countries in grain markets could cooperatively agree to refrain from such government intervention, working through the World Trade Organization, world price volatility could be lower.

In the meantime, some obvious steps should be taken.  It is too bad that the G20 attempt to do away with bio-fuel subsidies has failed, so far. Ethanol subsidies, such as those paid to American corn farmers, do not accomplish policymakers’ avowed environmental goals, but do divert grain and thus help drive up world food prices. By now this should be clear to everybody. But one cannot really expect the G-20 agriculture ministers to be able to fix the problem. After all, their constituents, the farmers, are the ones pocketing the money. The US, it must be said, is the biggest obstacle here.

What the G-20 farm ministers — meeting for the first time June 23 — have agreed is to forge an Agricultural Market Information System to improve transparency in agricultural markets, including information about production, stocks, and prices. More complete and timely information might indeed help.

But speculation is not necessarily destabilizing. Sarkozy is right that leverage is not necessarily good just because the free market allows it.  And that speculators occasionally act in a destabilizing way. But speculators more often act as detectors of changes in economic fundamentals and provide the signals that smooth fluctuations. In other words, they often are a stabilizing force.

The French have not yet been able to obtain agreement from the other G-20 members on measures aimed at regulating commodity speculators, such as limits on the size of their investment positions. I hope it stays that way. Shooting the messenger is no way to respond to the message.

[This op-ed appeared via Project Syndicate.  Comments can be posted at that site.]

Friday marks 200 days in office for President Obama.   “How has he done?” asks Fortune.

The first thing to say is that Barack Obama took over the presidency at an extremely difficult time. A variety of analogies suggest themselves: He is Harry Houdini who has been thrown in the river, in a straitjacket, with chains wrapped around him. Or he has taken over as the captain of a ship with a rotting hull, while the ship is under attack in a hurricane. To capture the state of the economy, perhaps the best metaphor is that Obama took over as pilot of an airplane in the middle of a steep dive. For a president precedent, he is Lincoln, who takes office as the South secedes. Or he is Roosevelt, who takes office at the depth of the Great Depression.

In any case, in light of the difficult circumstances, I think Obama has done amazingly well.

The financial markets were in free-fall six months ago. Bank spreads were at historic highs (a good indicator of just how outside-the-box this financial crisis was). GDP contracted at an annual rate of about 6 % in the last quarter of 2008 and the first quarter of this year.

Since then, the airplane has begun to level off. Those bank spreads are down to more normal levels. GDP declined at an annual rate of “only” 1% according to last Friday’s advance estimate; if I had to guess, we will see a bottom in the second half of the year and could see some positive growth. I give a lot of credit to the fiscal stimulus, to the monetary stimulus, and to the financial repair measures, as messy as those inevitably were.

At the time our new president took office in January, there was a danger that this could be not only the worst of the post-war recessions, but as bad as Japan in the 1990s. I think we have now avoided that. We have learned from mistakes in the past, particularly the mistakes of the Depression – those made by the Federal Reserve, Hoover, and also Roosevelt. Obama has the advantage of the lessons of the 1930s to learn from.   But he has the disadvantage of having inherited an exploding path of debt (unnecessarily incurred by this predecessor).    The debt is the rotting hull of the ship of state.

Regarding February’s stimulus package, some commentators said it was too small, some said it was too large.  In truth, it was both.   It was too small by itself to return us to full employment, to knock out the recession.   In order to bring us back to full employment, we would  need a boost to spending several times as big.  And yet, at the same time, it was too large to guarantee that we avoid losing the confidence of our international creditors.   If they stop buying our bonds, US long-term interest rates could rise sharply.   (China — the largest holder of US Treasuiy securities — has already begun to ask questions about the value of US debt.)     But the Administration struck an appropriate balance between these two competing concerns. 

People are angry about the big bonuses that are still being paid to those in the financial sector who got us into this problem. Entirely understandable. But don’t forget that, from the beginning, the goal was to prevent a depression in the general economy. That has been accomplished. You don’t punish someone who has been smoking in bed by allowing the resultant fire to burn down the block. The Administration and the Fed always admitted freely that helping some undeserving financiers would be an undesirable but necessary side effect of the rescue plan. And do you remember all the pundits who warned that the rescue could not work unless the banks were temporarily nationalized? Or all the cynics who dismissed claims that the Treasury would recoup a share of the budget costs as firms like Goldman Sachs repaid their loans with interest?

In my view, overall, Obama has gotten far more things right than wrong. He has bravely proposed things that most sensible economists — whether Republican or Democrat — have long favored. Proposing is not always the same as enacting; there is the matter of Congress. But he has tried to get them passed, and has tried to do it in a bipartisan way.  (That bipartisanship constraint is one of the Houdini chains.)

Washington has always been stymied by the political constraints of what can pass Congress.  Often presidents figure that special interest groups will block sensible reforms, so why waste political capital trying? But an example, which I find extremely encouraging, including symbolically, is that (with the help of Defense Secretary Robert Gates), Obama proposed to end spending on the F22 fighter. The F22 is probably the most egregious example in the defense budget of spending on hugely expensive weapons systems that the Pentagon doesn’t want because they are not useful for today’s national security needs. To my surprise, Obama actually prevailed  on this.

I can also name two areas where he proposed very sensible legislation that a heavy majority of economists of both parties would support, and yet where he has lost in Congress (at least so far). One is cutting agricultural subsidies to agribusiness and rich farmers. Another is auctioning off most of the greenhouse gas emission permits in any plan like the Waxman-Markey Bill, rather than giving them away to industry.  (Obama’s proposal was to use the proceeds of the auctions to reduce the marginal tax rate on low-income workers, to “Make Work Pay,” which would have been an excellent use of the funds.)

But the fact that he is trying, and that he is winning some of the battles, is important.  He is willing to fight the fight, while yet compromising when politically necessary. It is tremendously important that the public take notice of these details. There are always particular interest groups that stand to lose from any given reform such as farm supports,  military procurement or emission permit auctions; if the general public pays no attention to the details and does not support the President on them, it means special interests will triumph over the general good as so often in the past.

If I had to find one mistake that the White House has made, the initial economic forecasts were too optimistic, at least with respect to the unemployment rate. It was an honest mistake, but a mistake nonetheless… not just with respect to the economics: politically, Obama would have been better to recognize the severity of the recession from day one.

Regarding the health plan, we as yet have no idea what the outcome will be. The big questions, of course, are how to reduce costs and how to pay for getting everybody insured. Instead of proposing an income surcharge on the wealthy, I would have preferred eliminating non-taxability of employer-provided health benefits— that’s what McCain was for in the campaign, and most economists as well. The non-taxability could have been retained for workers in lower income brackets if the White House felt this was essential.  At the least, Senator Kerry’s astute version, which is aimed at curbing the effective taxpayer subsidy in the cases of the most egregiously expensive health care insurers, should be politically saleable.   You can call Obama’s failure, so far, to move in this direction a second mistake. But, since Fortune asked my opinion of how much the President has done right versus wrong, I put the score at 98 to 2. 

[Any readers wishing to comment on this post are encouraged to go to Seeking Alpha.]

If strong economic growth is not the explanation for the large increases since 2001 in prices of virtually all mineral and agricultural commodities, then what is? One wouldn’t want to try to reduce commodity markets to a single factor, nor to claim proof of any theory by a single data point. Nevertheless, the developments of the last six months provided added support for a theory I have long favored: real interest rates are an important determinant of real commodity prices. High interest rates reduce the demand for storable commodities, or increase the supply, through a variety of channels:

• by increasing the incentive for extraction today rather than tomorrow (think of the rates at which oil is pumped, copper mined, forests logged, or livestock herds culled)
• by decreasing firms’ desire to carry inventories (think of oil inventories held in tanks)
• by encouraging speculators to shift out of spot commodity contracts (think gold), and into treasury bills.

All three mechanisms work to reduce the market price of commodities, as happened when real interest rates where high in the early 1980s. A decrease in real interest rates has the opposite effect, lowering the cost of carrying inventories, and raising commodity prices, as happened in the 1970s, and again during 2001-2004. It’s the original “carry trade.”

The theoretical model can be summarized as follows:

A monetary expansion temporarily lowers the real interest rate (whether via a fall in the nominal interest rate, a rise in expected inflation, or both – as now). Real commodity prices rise. How far? Until commodities are widely considered “overvalued” — so overvalued that there is an expectation of future depreciation (together with the other costs of carrying inventories: storage costs plus any risk premium) that is sufficient to offset the lower interest rate (and other advantages of holding inventories, namely the “convenience yield”). Only then do firms feel they have high enough inventories despite the low carrying cost. In the long run, the general price level adjusts to the change in the money supply. As a result, the real money supply, real interest rate, and real commodity price eventually return to where they were. The theory is the same as Rudiger Dornbusch’s famous theory of exchange rate overshooting, with the price of commodities substituted for the price of foreign exchange.There was already some empirical evidence to support the theory: Monetary policy news and real interest rates, along with other factors, do appear to be significant determinants of real commodity prices historically. (For a simpler illustration, see graph below).

But the events since August 2007 provide a further data point. As economic growth has slowed sharply, both in the US and globally, the Fed has reduced interest rates, both nominal and real. Firms and investors have responded by shifting into commodities, not out. This is why commodity prices have resumed their upward march over the last six months, rather than reversing it.

It is hard to remember now, but mineral and agricultural commodities were considered passé less than ten years ago. Anyone who talked about sectors where the product was as clunky and mundane as copper, corn, and crude petroleum, was considered behind the times. In Alan Greenspan’s phrase, GDP had gotten “lighter;” the economy was becoming weightless, “dematerializing.” Agriculture and mining no longer constituted a large share of the New Economy, and did not matter much in an age dominated by ethereal digital communication, evanescent dotcoms, and externally outsourced services. The Economist magazine in a 1999 cover story forecast that oil might be headed for a price of $5 a barrel.

Since then, of course, we have seen tremendous increases in the prices of most mineral and agricultural commodities, many of them hitting records in nominal and even real terms (see graph). Oil is now well above $100 a barrel, and gold has just crossed the $1000 an ounce line.

The question is why.

There could well be merit to many of the explanations that have been offered for the rise in the price of oil. One is the “peak oil hypothesis,” and another is geopolitical uncertainty in Russia, Nigeria, Venezuela and – above all – the Gulf. Corn prices have been impacted by American subsidies for biofuel. And other special microeconomic factors are relevant in other specific sectors. But it cannot be a coincidence that mineral and agricultural prices have risen virtually across the board. Some macroeconomic explanation is called for.

The popular explanation since 2004 has been rapid growth in the world economy. The strongest growth has of course been coming from China and other recently minted manufacturing powerhouses in Asia, but the expansion has been unusually broad-based – including up to last year the United States and even a reinvigorated Europe. So growth has pushed up demand for energy, minerals, farm products, and other industrial inputs, right?

This reigning explanation now looks suspect. Since last summer the US economy has slowed down noticeably, and is probably entering a recession. Despite talk of decoupling, it is clear that other countries are also slowing down at least to some extent. In its most recent forecast, the IMF World Economic Outlook revised downward the growth rate for virtually every region, including China. The overall global growth rate for 2008 has been marked down by 1.1% (from 5.2 % in July 2007, just before the sub-prime mortgage crisis hit, to 4.1 % as of January 29, 2008). And prospects continue to deteriorate. Yet commodity prices have found their second wind over precisely this period! Up some 25% or more since August 2007, by a number of indices. So much for the growth explanation.

How to explain commodity prices up while the economy turns down? I will offer my answer in my next posting, tomorrow.