SAN FRANCISCO – Of all the challenges I face as a CEO, nothing is more critical than attracting and retaining talented people. Declining birth rates are starting to deplete the global labor pool. This problem is particularly acute in Japan, China, South Korea, and most of Western Europe, which have "sub-replacement" birth rates--that is, the number of children born is below the level needed to sustain population and ultimately employment levels. It's also becoming a major concern in the United States, especially as the country's declining high-school graduation rate and soaring college costs narrow the supply of highly skilled, highly technical people. As companies worldwide compete for ever-scarcer human resources, we're going to have to get much better at identifying, attracting, evaluating, and retaining the best people.