UNITED NATIONS (AP) The world is turning to dust, with lands the size of Rhode Island becoming desert wasteland every year and the problem threatening to send millions of people fleeing to greener countries, the United Nations says. One-third of the Earth's surface is at risk, driving people into cities and destroying agriculture in vast swaths of Africa. Thirty-one percent of Spain is threatened, while China has lost 36,000 square miles to desert an area the size of Indiana since the 1950s. This week the United Nations marks the 10th anniversary of the Convention to Combat Desertification, a plan aimed...