Engineers say a forest of 100,000 "artificial trees" could be deployed within 10 to 20 years to help soak up the world's carbon emissions. The trees are among three geo-engineering ideas highlighted as practical in a new report. The authors from the Institution of Mechanical Engineers say that without geo-engineering it will be impossible to avoid dangerous climate change. The report includes a 100-year roadmap to "decarbonise" the global economy. No silver bullet Launching the report, lead author Dr Tim Fox said geo-engineering should not be viewed as a "silver bullet" that could combat climate change in isolation. He told BBC News it should be used in conjunction with efforts to reduce carbon emissions and to adapt to the effects of climate change. Many climate scientists calculate that the world has only a few decades to reduce emissions before there is so much carbon dioxide in the atmosphere that a dangerous rise in global temperature is inevitable. The authors of this report say that geo-engineering of the type they propose should be used on a short-term basis to buy the world time, but in the long term it is vital to reduce emissions. They define two types of geo-engineering, said Nem Vaughan of University of East Anglia. "The first category attempts to cool the planet by reflecting some of the sunlight away. The problem with this is that it just masks the problem," he said. "The other type of geo-engineering is to remove carbon dioxide from the atmosphere and store it."