The dollar is the world’s go-to currency. But for how much longer? Will the dollar’s status as the only true global currency be irreparably damaged by the battle in the US Congress over raising the federal government’s debt ceiling? Is the dollar’s “exorbitant privilege” as the world’s main reserve currency truly at risk?

To be sure, the purveyors of dollar doom and gloom have cried wolf before. When the subprime-mortgage crisis hit, it was widely predicted that the dollar would suffer. In fact, the greenback strengthened as investors seeking a safe haven rushed into US Treasury bonds. A year later, when Lehman Brothers failed, the dollar benefited from the safe-haven effect yet again.

Data from the International Monetary Fund confirm that these shocks caused little (if any) decline in the dominance of the dollar in central banks’ holdings of foreign-currency reserves. Likewise, data gathered by the Bank for International Settlements show that the dollar dominates global foreign-exchange transactions as much as it did in 2007.

But a default on US government debt precipitated by failure to raise the debt ceiling would be a very different kind of shock, with very different effects. In response to the subprime disruption and Lehman’s collapse, investors piled into US government bonds, because they offered safety and liquidity – prized attributes in a crisis. These are precisely the attributes that would be jeopardized by a default.

The presumption that US Treasury bonds are a safe source of income would be the first casualty of default. Even if the Treasury paid bondholders first – choosing to stiff, say, contractors or Social Security recipients – the idea that the US government always pays its bills would no longer be taken for granted. Holders of US Treasury bonds would begin to think twice.

The impact on market liquidity would also be severe. Fedwire, the electronic network operated by the US Federal Reserve to transfer funds between financial institutions, is not set up to settle transactions in defaulted securities. So Fedwire would immediately freeze. The repo market, in which loans are provided against Treasury bonds, would also seize up.

For their part, mutual funds that are prohibited by covenant from holding defaulted securities would have to dump their Treasuries in a self-destructive fire sale. Money-market mutual funds, virtually without exception, would “break the buck,” allowing their shares to go to a discount. The impact would be many times more severe than when one money-market player, the Reserve Primary Fund, broke the buck in 2008.

Indeed, the entire commercial banking sector, which owns nearly $2 trillion in government-backed securities – would be threatened. Confidence in the banks rests on confidence in the Federal Deposit Insurance Corporation, which insures deposits. But it is not inconceivable that the FDIC would go bust if the value of the banks’ Treasury bonds cratered.

The result would be a sharp drop in the dollar and catastrophic losses for US financial institutions. Beyond the immediate financial costs, the dollar’s global safe-haven status would be lost.

It is difficult to estimate the cost to the US of losing the dollar’s position as the leading international currency. But 2% of GDP, or one year’s worth of economic growth, is not an unreasonable guess. With foreign central banks and international investors shunning dollars, the US Treasury would have to pay more to borrow, even if the debt ceiling was eventually raised. The US would also lose the insurance value of a currency that automatically strengthens when something goes wrong (whether at home or abroad).

The impact on the rest of the world would be even more calamitous. Foreign investors, too, would suffer severe losses on their holdings of US treasuries. In addition, disaffected holders of dollars would rush into other currencies, like the euro, which would appreciate sharply as a result. A significantly stronger euro is, of course, the last thing a moribund Europe needs. Consider the adverse impact on Spain, an ailing economy that is struggling to increase its exports.

Likewise, small economies’ currencies – for example, the Canadian dollar and the Norwegian krone – would shoot through the roof. Even emerging-market countries like South Korea and Mexico would experience similar effects, jeopardizing their export sectors. They would have no choice but to apply strict capital controls to limit foreign purchases of their securities. It is not inconceivable that advanced countries would do the same, which would mean the end of financial globalization. Indeed, it could spell the end of all economic globalization.

Sane governments do not default when they have a choice – especially not when they enjoy the “exorbitant privilege” of issuing the only true global currency. We are about to find out whether the US still has a sane government.

The opinions expressed here are those of the author, not necessarily those of the World Economic Forum. Published in collaboration with Project Syndicate.

Author: Barry Eichengreen is professor of economics and political science at the University of California, Berkeley.

Image: An empty speaker’s lectern is seen in the rain outside the U.S. Capitol in Washington, October 10, 2013. REUTERS/Jonathan Ernst

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