A series of sudden, unfavorable events has in just a matter of weeks changed bright optimism about the pace of growth in the global economy this year to a deepening sense of doubt. The warning signs are plentiful: Tumbling stock prices around the world, disappointing economic reports in the U.S. and China, hasty interest-rate increases in major developing countries including Turkey, India and South Africa, and whispers of disappointment in corporate earnings conference calls. They are combining to send a signal that the global economy might not be on the strong footing it appeared to be at the start of 2014. Another closely watched indicator will arrive Friday, when the Labor Department releases its estimate of U.S. job growth in January. Still, that report, like other recent U.S. releases, could offer murky guidance due to quirks related to bad winter weather, only adding to uncertainty about the outlook. Investors […]