Recently, Y.-H. Percival Zhang and colleagues demonstrated a method of converting cellulose into starch and glucose. Zhang thinks that it can be scaled up into an effective industrial process, one that could produce a thousand calories of starch for less than a dollar from cellulosic waste. This would be a good thing. It’s not just that are 7 billion people – the problem is that we have hardly any food reserves (about 74 days at last report). The usual assumption is that any drought or blight would be local, but that isn’t necessarily so. We might have another Tambora-style eruption, or an asteroid big enough to generate tidal waves and kick up a lot of dust – or wheat rust might get out of control.
If this works, we might have a reserve in hand. At least until the population runs up to the new Malthusian limit.