• World population expected to hit 7 billion next year.
• China overtakes Japan, now world's second-largest economy.
• Leading candidate to replace Warren Buffet at Berkshire is former Tiananmen Square protest leader.
• July deadliest month in nine-year war in Afghanistan.
• Police seize $1.7 billion in pot found in California mountains.
• U.S.-Mexican border still among safest places in the country.