As 21 timber buildings over 50 meters (164 feet) will be completed in Europe by the end of year and a massive 80-story building is planned in Chicago, timber seems poised for a comeback in the construction industry in the form of mass timber. Mass timber is made of large structural panels, posts, and beams glued under pressure or nailed together in layers, with the wood’s grain stacked perpendicular for more strength. The question being asked is just how sustainable this sort of building material is. In addition to, how are forests that produce mass timber managed and how much CO2 would be emitted in the logging, manufacture, and transport of the wood? Proponents of mass timber say it does have real promise if a fully sustainable life cycle comes together.