> By contrast, there is no danger of running out of paper. We can always grow more trees, and that is in fact a decent way of removing carbon from the atmosphere. The silicon used to make glass is one of the most abundant elements on Earth.

Please correct me if I am wrong, but from what I understand, not all sand is created equal. Desert sand, like in the Sahara Desert, is eroded by wind. The smooth, round, and tiny grains are practically useless for both construction concrete and high-grade glassmaking. We want something called silica sand. Moreover, while industrial sand may be abundant worldwide, the same localized shortages that we face with petroleum or cobalt (from the article) also apply to sand.