A global report card issued by the United Nations just two weeks before an international environmental summit has given low marks to the world’s ecological condition. Among the report’s more shocking findings: Three million people die annually from air pollution, while more than 1 billion people — a sixth of the world’s population — lack access to safe drinking water. The report also found that the world’s forested areas shrank by 2.4 percent in the 1990s, with Africa taking the hardest hit, losing 7 percent of its forests. The world’s environment is also threatened by growing energy consumption; in the last decade, energy use declined in Eastern Europe, stayed steady in Western Europe, and increased in North America. The World Summit on Sustainable Development, the conference designed to address these issues, will be held in Johannesburg, South Africa, later this month, but U.S. President Bush is expected to be notably absent.