Nobody makes buildings out of wood anymore. Why? Because wood isn't especially strong (relative to steel), it involves cutting down trees, it burns readily, and creepy crawly things live and/or feast on it. Despite these horrible shortcomings, brave architects are now planning to build a 30-story wooden skyscraper in Vancouver.
There are a bunch of reasons why we don't have wooden skyscrapers already, but two of the biggest ones seem to be strength and the fact that wood tends to be a little bit, you know, burney. As far as strength goes, skyscraper (or any building) has to be strong enough to support its own weight, and once you get above a couple floors, wood (by itself) has a hard time with that. And seeing as wood is what most people use for making fires, you'd think that making big buildings out of it would be a terrible idea.
Both of these problems can be solved with large pieces of laminated timber, which is just a bunch of thin pieces of wood glued together. This kind of timber is very light but very strong, and gets even stronger if you arrange the wood such that the strands are fused together at right angles. And believe it or not, wood is actually quite good at resisting fire: the outside chars, which serves to insulate the inside, preserving the overall integrity of the structure.
The other reason why wooden skyscrapers might be a good way to go in the future is that the materials use to build them (i.e. trees) are a renewable resource that takes carbon out of the environment instead of putting it in. Concrete, for example, pukes out about nine kilos of CO2 for every ten kilos of concrete, which is fairly horrendous. Wood, on the other hand, sucks carbon out of the atmosphere, and as long as you harvest sustainably, cutting down trees can be a good thing.
Of course, nobody would take any of this seriously were it not for the fact that wooden construction is getting to the point where it's demonstrably cheaper than building out of things like concrete and metal. Cheaper and eco-friendlier are powerful terms these days, and the Canadians aren't the only ones interested: there are also plans afoot for wooden skyscrapers in Austria and Norway.