By now, we all know that long-run forecasts are a fool's errand and that all of the doomsday forecasts have been wrong. We also know that they keep on coming.
Historian Stephen Davies recounts "The Great Horse-Manure Crisis of 1894" in the current issue of The Freeman (some of contents on-line but, unfortunately, not Davies' piece). All urban non-pedestrian traffic was horsepowered and the stuff kept piling up. "In New York in 1900, the population of 100,000 horses produced 2.5 million pounds of horse manure per day ... " And, "Writing in the Times of London in 1894, one writer estimated that in 50 years every street in London would be buried under nine feet of manure."
Even better is Davies' reports that, "In 1898 the first international urban planning conference convened in New York. It was abandoned after three days, instead of the scheduled ten, because none of the delegates could see any solution to the growing crisis posed by urban horses and their output."