"Growth almost everywhere," he said, "is a bit weaker than we forecast last April" - and that forecast itself was weak.
In 2013, the IMF expects the world economy to grow 3.1 percent, the same as in 2012 and down from an April forecast of 3.3 percent.
More relevant: the forecast is much lower than the actual average growth of 4.6 percent achieved in 2010 and 2011.
For 2014, global growth is predicted to rebound to 3.8 percent, but this could be a triumph of hope over experience.
Even the IMF concedes that "downside risks . . . still dominate." One problem is that some emerging-market countries relied on policies that provided artificial and temporary stimulus. These now need to be replaced.
Consider China. Its growth has depended heavily on credit-financed investment in factories and housing.
As a share of the economy (gross domestic product), investment rose from 39 percent before the financial crisis to 45 percent now, noted Blanchard. There's a widespread view that much of this investment is premature or unneeded.
So, he said, China faces a dilemma: Continue promoting investment and risk more unproductive projects and loan losses; or tighten credit and slow the economy, because higher consumer spending won't fully offset lower investment
There's no easy way out.
India grapples with a similar situation. Growth flowed from expansive budgets and loose money policies that are unsustainable, writes economist Arvind Subramanian of the Peterson Institute.
These policies left a legacy of "high fiscal deficits, close to double-digit inflation and high [trade] deficits."
Again, no easy way out.
Europe, the United States and Japan also face unsavory choices. All wrestle with what the IMF calls "fiscal consolidation" - reducing budget deficits.
The underlying problem: costly welfare states with aging populations. Either spending must be cut or taxes must be raised.
Both may depress the economy, but if nothing is done, higher debt levels may ultimately cause higher interest rates.
Though the decisions are domestic, the repercussions may be global, because these advanced nations represent roughly 40 percent of the world economy.
The bad news is that the bad news may be infectious.
Blanchard said he detects in France and Germany "a general lack of confidence in the future, which, if it doesn't turn around, . . . may end up being partly self-fulfilling."
It's not just France and Germany.