The recent research related to the trilemma (see here) confirms that policymakers who are willing to sacrifice control of the exchange rate or capital flows can implement monetary policy. For most central banks, this means using a short-term interest rate, such as the Federal Funds rate in the case of the Federal Reserve in the U.S. or the Bank of England’s Bank Rate. But the record raises doubts about whether this is sufficient to achieve the policymakers’ ultimate economic goals.
The short-term interest rate does not directly affect investment and other expenditures. But it can lead to a rise in long-term rates, which will have an effect on spending by firms and households. The relationship of short-term and long-term rates appears in the yield curve. This usually has a positive slope to reflect expectations of future short-term real rates, future inflation and a term premium. Changes in short-term rates can lead to movements in long-term rates, but in recent years the long-term rates have not always responded as central bankers have wished. Former Federal Reserve Chair Alan Greenspan referred to the decline in U.S. long-term rates in 2005 as a “conundrum.” This problem is exacerbated in other countries’ financial markets, where long-term interest rates are affected by U.S. rates (see, for example, here and here) and global factors.
Central banks that sought to increase spending during the global financial crisis by lowering interest rates faced a new obstacle: the zero lower bound on interest rates. Policymakers who could not lower their nominal policy rates any further have sought to increase inflation in order to bring down real rates. To accomplish this, they devised a new policy tool, quantitative easing. Under these programs, central bankers purchased large amounts of bonds with longer maturities than they use for open market transactions and from a variety of issuers in order to bring down long-term rates. The U.S. engaged in such purchases between 2008 and 2014, while the European Central Bank and the Bank of Japan are still engaged in similar transactions. As a consequence of these purchases, the balance sheets of central banks swelled enormously.
In an open economy, there is another channel of transmission to the economy for monetary policy: the exchange rate. If a central bank can engineer a currency depreciation, an expansion in net exports could supplement or take the place of the desired change in domestic spending. A series of currency depreciations last summer led to concerns that some central banks were moving in that direction.
But there are many reasons why using exchange rate movements are not a solution to less effective domestic monetary policies. First, if a central bank wanted to use the exchange rate as a tool, it would have to fix it. But it then would have to surrender control of domestic money or block capital flows to satisfy the constraint of the trilemma. Second, there is no simple relationship between a central bank’s policy interest rate and the foreign exchange value of its currency. Exchange rates, like any asset price, exhibit a great deal of volatility. Third, the impact on an economy of a currency depreciation does not always work the way we might expect. Former Federal Reserve Chair Ben Bernanke has pointed out that the impact of a cheaper currency on relative prices is balanced by the stimulative effect of the easing of monetary policy on domestic income and imports.
Of course, this does not imply that central banks need not take notice of exchange rate movements. There are other channels of transmission besides trade flows. The Asian crisis showed that a depreciation raises the value of debt liabilities denominated in foreign currencies, which can lead to bankruptcies and banking crises. We may see this phenomenon again in emerging markets as those firms that borrowed in dollars when U.S. rates were cheap have difficulty in meeting their obligations as both interest rates and the value of the dollar rise (see here).
Georgios Georgiadis and Arnaud Mehl of the European Central Bank have investigated the impact of financial globalization on monetary policy effectiveness. They find that economies that are more susceptible to global financial cycles show a weaker response of output to monetary policy. But they also find that economies with larger net foreign currency exposures exhibit a stronger response of output to monetary policy shocks. They conclude: “Overall, we find that the net effect of financial globalization since the 1990s has been to amplify monetary policy effectiveness in the typical advanced and emerging markets economy.”
While their results demonstrate the importance of exchange rate in economic fluctuations, that need not mean that monetary policy is “effective” as a policy tool. As explained above, flexible (or loosely managed) exchange rates are unpredictable. They can change in response to capital flows that react to foreign variables as well as domestic factors. The trilemma may hold in the narrow sense that central banks maintain control of their own policy rates if exchange rates are flexible. But what the policymakers can achieve with this power is circumscribed in an open economy.
