Scientists are testing new geo-engineering technologies - the modification of the earth's climate on a large scale - that, according to them, will be able to limit the effects of global warming, or even cool the planet. The capturing of CO2 in the atmosphere through artificial tree forests or reflecting sunlight by creating a shield in the mesosphere are some of the new technologies being tested. What are these processes? How do they work? Is it really already possible? Tested in the laboratory, will they work on a large scale? What are the risks for the planet? Hear the experts: Olivier Boucher (France) Sorbonne University / CNRS Ken Caldiera (USA) Standford University Klaus Lackner, Shahrzad Badvipour & Allan Wright (USA) Arizona State University Graciela Chichilnisky (USA) Global Thermostat Bergur Sigfusson (Iceland) Reykjavik Energy Michael Riedjik, Farah Nour & Peter Gross (Canada) Oceaneos Silvia Ribeiro & Jim Thomas - ETC Group Robert Wood & Thomas Ackerman (USA) University of Washington Simone Tilmes, Michael J. Mills & David Hosansky (USA) NCAR Linda Schneider (Germany) Heinrich Böll Foundation Gernot Wagner (USA) Harvard University Leslie Field & Roman Decca - Ice 911 Tim Kruger & Steve Rayner (UK) Oxford University Kelly Wanser - Marine Cloud Brightening Project