Projections for the evolution of green technologies to help curb greenhouse gas emissions are overly optimist, according to researchers writing in Nature. They say policymakers will need to implement stronger measures to reverse global warming.
ROBERT SIEGEL, host: Last year, a committee of scientists laid out steps it saw as necessary to combat climate change. The group was convened by the United Nations. And it said that eventually, the world will need to wean itself from oil, coal and natural gas.</s>ROBERT SIEGEL, host: As NPR's Richard Harris reports, that task may be even more daunting than the scientists suggested.</s>RICHARD HARRIS: That issue here is just how much heavy lifting we'll all have to do in order to push the world's economy away from fossil fuels. The Intergovernmental Panel on Climate Change, the IPCC, argued that some of this will happen all by itself, just by the nature of how technology is evolving.</s>RICHARD HARRIS: Roger Pielke Jr. at the University of Colorado says that's not necessarily true.</s>RICHARD HARRIS: Professor ROGER PIELKE JR. (Environmental Studies, University of Colorado): The assumptions in all of the scenarios used by the IPCC assume that the world will get more efficient as economic development continues.</s>RICHARD HARRIS: That efficiency implies that carbon emissions won't grow as fast as the world's economy does. The IPCC projects that natural evolution of technology will give us a bit of a free ride, and indeed that was so at least through the 1980s and 1990s.</s>Prof. PIELKE: But it turns out that the trend has reversed itself, at least in the short term.</s>RICHARD HARRIS: In recent years, the world has actually become less efficient and more polluting. One major reason for that is there's a building boom in China of inefficient coal-fired power plants, so pollution there is growing even faster than the economy.</s>RICHARD HARRIS: Pielke and colleagues write in Nature that this has thrown off the IPCC projections. And if improvements in efficiency remain stalled out, we'll have to make even bigger changes in our way of life to achieve the same reductions.</s>Prof. PIELKE: The first reaction to our paper will be to say, well, this is a much harder challenge. But I guess our view is that the challenge is impossible if we don't fully understand it.</s>RICHARD HARRIS: Pielke acknowledges that the recent trend could be an aberration and that technological efficiencies will once again help offset the growth of carbon dioxide driven by global economic growth.</s>RICHARD HARRIS: Dutch scientist, Bert Metz, who played a leading role in the IPCC report, still stands by the report's assumption that natural technological change will ultimately help curb emissions.</s>Dr. BERT METZ (Co-Chair, IPCC WG III): We know from our own experience, but also from well-documented studies, that technologies are improving all the time.</s>RICHARD HARRIS: Just think about how different computers are now compared with 20 years ago. He says it's reasonable to assume the last few years are a blip. And in the long run, technologies will improve a lot, making our economies more efficient and less polluting.</s>Dr. BERT METZ (Co-Chair, IPCC WG III): We're not sure yet. The scenarios are looking at 100-year timeframe, so that's a very long period and you should be very careful not to jump to conclusions.</s>RICHARD HARRIS: Whether the natural evolution of technology gives us a big boost in dealing with climate change or no boost at all, Metz and Pielke agree on one thing — policymakers will have to push hard to drive a lot of the changes required to slow global warming.</s>RICHARD HARRIS: Richard Harris, NPR News.