The International Monetary Fund is out with the summer update to its World Economic Outlook, its regular assessment of the global economy. It's not that good. The IMF thinks that global growth will be slower this year than it had expected as recently as April. The 3.1 percent rise in global GDP the fund now forecasts for this year is a downward revision of 0.2 percentage points from the April forecast.

The downward revision covered much of the world: the United States, the euro zone, China and other emerging markets. The major exceptions to the pessimistic tone were Japan and Britain, which both received upward revisions.

As always, IMF chief economist Olivier Blanchard gave an interesting round-the-world tour of analyses of the forces buffeting the major economies in a press conference at IMF headquarters Tuesday morning.

On emerging markets: Blanchard characterized the downward revisions as being driven first by weaker demand for exports out of Europe and other developed markets. That was a major reason for, for example, a new estimate that China will grow 7.8 percent this year (not the 8.1 percent seen in April) and Brazil will grow 2.5 percent (down from 3 percent). But Blanchard argued that only explains part of the slowdown. "This slowdown in growth has not come with much of a decrease in inflation," he said. "This suggests to us that potential output has slowed down in line with actual output. This has an important implication, which is that growth in emerging market economies will remain high, but maybe substantially lower than it was before the crisis."

On the United States: The IMF has been a drumbeat critic of U.S. authorities for, saying they have moved too abruptly to reduce deficits and  tighten fiscal policy. Blanchard kept on message, attributing the 0.2 percentage point drop in the Fund's 2013 growth projection for the United States to fiscal policy. "What has happened is that stronger than expected and stronger than desirable fiscal consolidation has been only partly offset by a good performance of the housing market, the result being a small downward revisions. If fiscal consolidation had been weaker, then growth in the US would be substantially higher.

On Europe: The major economies of Spain and Italy are contracting, and core European economies like France and Germany aren't doing that great, either, according to the fund. In the hard hit crisis countries, "there are improvements in relative costs and competitiveness, and an increase in export market shares," Blanchard said. "But this is not enough for increased demand . . .high interest rates and fiscal consolidation are clearly playing a major role."

On recent market volatility: Blanchard has an interesting, nuanced view of the freak-out on global bond markets that followed a Federal Reserve press conference last month making clear the central bank will soon taper its quantitative easing policies. "We attribute the high volatility of financial markets not so much to news from the Fed," Blanchard said, "but to the sudden realization by investors that QE would eventually come to an end. As they tried simultaneously to rebalance portfolios in the U.S. and abroad, there was some overshooting and high volatility. Going forward, we think this was very much a repricing episode and we expect volatility to decrease relative to the highs of the recent past. But one cannot rule further attacks of nerves along the way."