Nye could be right (though that says nothing about whether use of fossil fuels is a contributing cause, much less the sole cause, of the warming trend), or he could be wrong in a very radical way: the paleoclimatological record shows that ice ages have always been preceded by a sharp warming trend. The best theory of causation for ice ages is that the arctic ice cap melting decreased the salinity of the North Atlantic (they all happened with the continents in more-or-less their current positions), shutting down the thermohaline circulation (the Gulf Stream). The extra open water and sudden cooling result in massive snowfalls and glaciation of what are now Canada, Alaska, Russia and the Nordic countries within a decade.
