I'm worried -- make that very worried -- about the first half of 2012 for investors.

Why? Because the global economic picture looks very unfriendly to financial markets in the first six months of the year.

Not so much because the forecast for growth is so bad. In early December, economists surveyed by the Philadelphia Federal Reserve Bank projected that the U.S. economy would grow by 2.1% in the first half of 2012. That's a long way from a recession, but it's not enough growth to cut quickly into today's high unemployment rate.

Barclays is projecting that growth in China will slow to an annual rate of 7.8% in the first quarter of 2012, the quarter the investment bank is forecasting as the slowest of 2012. And even in the eurozone, the origin of the current global economic slowdown, the Organisation for Economic Co-operation and Development forecasts that growth will turn negative in the first part of 2012, but not by much. The end-of-November prediction of a 0.4% contraction in the first quarter of the year would amount to just a mild recession.

Not the best of times, certainly, but not exactly a replay of 2008, either. So why am I so worried?

Because stock market history argues that the correlation of the magnitude of economic growth and stock prices is not all that strong. More important are the direction of change in rates of economic growth and the degree of uncertainty about future growth rates. On both those two measures -- direction of change and uncertainty -- the first half of 2012 scores as a very worrisome period.

Image: Jim Jubak

Jim Jubak

China's growth rate? Anyone's guess

Let me start with China to show you what I mean. Growth in China is key to demand for global commodities such as iron ore, copper, coal and oil, and for demand for goods and services that range from Coach (COH, news) bags to Maxwell Technologies (MXWL, news) ultracapacitors to Ctrip.com International (CTRP, news) travel bookings and HSBC (HBC, news) investment banking services.

So what will the growth rate for China's economy be in 2012?

Even looking at a fairly optimistic forecast like that from Barclays, the direction of the trend isn't comforting. Barclays calls for growth in the Chinese economy to slow from an annual rate of 9.1% in the third quarter of 2011 to 8.3% in the fourth quarter of 2011 to 7.8% in the first quarter of 2012.

And the conviction in any call on China's growth rate is fairly low. Which means, to look at it the other way around, the uncertainty is fairly high.

I have a sense that any of these projections is only provisional and that analysts are still rushing to play catch-up with events. Barclays has cut its forecast for all of 2012 to 8.1% from 8.4%. Morgan Stanley has cut its forecast to 8.4% from 8.9%. But you don't have to look far to find more bearish forecasts.

And even those provisional forecasts are coming with more caveats. The Morgan Stanley forecast, for example, is for a most likely scenario resulting in 8.4% growth. There's also a bearish scenario resulting in a drop to 7.7% growth for 2012.

Thank Europe for the doubts

The uncertainty in forecasts for China, the United States and the global economy as a whole largely stems from uncertainty over the depth of the slowdown in the eurozone. The lower the growth in the eurozone, the lower growth is likely to be in the countries that trade with that group of nations.

The European Central Bank captured that high uncertainty in the forecast for 2012 growth issued by its economists on Dec. 8. The bank said that for 2012, growth in the eurozone would fall between 1% -- weak growth -- and a negative 0.4% -- a mild recession.

Compare that with the last forecast from the bank's economists, which looked for growth in 2012 of somewhere between 2.2% and 0.4%. On the numbers, you could say that the degree of uncertainty is lower in the latest call -- the difference between the high and low ends of the forecasts has diminished to a 1.4 percentage point spread from the prior 1.8 percentage point spread. But I'd argue that from an investor's point of view, the uncertainty has actually increased since the difference between high and low forecasts is now the difference between mild growth and mild recession instead of between solid growth and mild growth.

With the trend pointing downward, investors can be forgiven for thinking that the next set of forecasts won't show a median of 0.3% growth for 2012 but a solidly negative forecast for the year.

And the recently announced grand plan to save the euro (is it Grand Plan No. 3 or No. 4? I've lost count) concentrates the risk in the first half of 2012. Even if you take European leaders' timetable as accurate (I wouldn't, but you can if you like), the permanent European Stabilization Mechanism, with its 500 billion euros in bailout funding, isn't set to go into operation until July. Nobody knows how long it will take the International Monetary Fund to get its promised 200 billion euros in new funding into position -- and nobody knows exactly what the IMF will do with that funding in support of eurozone bond markets and eurozone governments.

What we do know is that the first quarter is loaded with funding needs. The Royal Bank of Scotland calculates that eurozone governments will need to sell 824 billion euros in debt in 2012, and that 225 billion of that will need to be raised in the first quarter of 2012. That's not the end of the eurozone's calls on the financial markets, either. Agencies and supranational bodies such as the temporary European Financial Stability Facility -- the bailout fund that is selling bonds to support Greece, Ireland and Portugal -- will have to issue 175 billion euros in debt in the first quarter. As much as 45 billion of that is needed for Ireland, Portugal and Greece.

Think any of this will be an easy sell in early 2012?

Especially not if, as many European constitutional experts now worry, the plan to fix the long-term problems of the euro through a new treaty, with somewhere between 17 and 26 signatories, faces a legal challenge. It's not clear that a group that is not the European Union -- and since the United Kingdom has rejected this approach, the proposed new treaty won't include all members of the European Union -- can utilize European Union bodies, such as the European Commission and the European Court of Justice, to enforce the budget mechanisms envisioned in the planned treaty, which was backed with such fervor by German Chancellor Angela Merkel. At the least, these doubts will hang over the treaty effort as it slowly advances through summit meeting after summit meeting.