Voice of America: A report by a number of leading conservation groups warns that unless prompt corrective measures are taken, the planet is heading toward an ecological credit crunch. For VOA, Tom Rivers reports from London. Cover of the Living Planet ReportThe report is simple and stark. Our demands on natural resources overreach what the Earth can sustain by almost a third. The World Wildlife Fund, the Zoological Society of London and Global Footprint Network all worked jointly on what is …