A commentary in this week’s issue of the journal Nature adds to the chorus of economists, climate scientists and experts in energy policy saying that the major approaches to combating global warming are deeply flawed. The Nature commentary is by Roger A. Pielke, Jr., a political scientist at the University of Colorado, Thomas Wigley, a climatologist at the National Center for Atmospheric Research, and Christopher Green, an economist at Ï㽶ÊÓƵ. The scientists argue that the IPCC, the pre-eminent body engaged in crystal-ball gazing about future climates, has sent out the wrong signals about the need for new technology to curb emissions.