Much is made, particularly amongst the cosplayers, within the Steampunk sub-culture not just of alternative history, but of the apocalypse. The two come together in The Peshawar Lancers by SM Stirling, whereby the effective destruction of Britain by meteor impact results in the wholesale moving of the centre of the British Empire to a new home in India. One of the 'ten steampunk books you must read', this is a text most SPs know or have heard of.
Films such as the newHollywood City of Ember, or the marvellous Wormtooth Nation are embedded in the notion of humanity escaping apocalypse, often underground, sometimes on another planet, and the loss of some vital knowledge often pertaining to the way back 'home'.
The current crop of apocalyptic visions have been rife since before the millenium of 2001 (which was actually the start of the new millenium, not 2000). The marking of a key date in the calendar is usually marked by a rise in apocalyptic or millenarian cults and cultural phenomenon - this time around, it was the Y2K bug which would kill all computers and wipe out humanity's collective electronic data, and before that the collective suicide of the Heaven's Gate cult. The end of the nineteenth century saw a rash of cults predicting the end of the world and a rise in spiritualism. Yet the ninteenth century also saw the technological, philosophical and intellectual advances which shaped the twentieth century.
All these elements - apocalypse, spriritualism, and technology - come together in steampunk, with a surprising array of influences and expressions. Western culture has maintained the apocalyptic fervour which grew in the late twentieth century far longer than in previous centuries, and has absorbed it into its fashion, books, films, and television programmes (just think of Heroes for instance). Academic concerns over social collapse continue to look to the past for solutions. Far from being a sub-culture, steampunk is at the confluence of these different cultural elements, but with a focus, with the current worries of climate change and economic collapse, upon how things may have been better with just a tweak here and a nudge there in the late nineteenth/early twentieth century. New developments in tackling transport and climate problems are directly influenced by the technologies of the eighteenth and nineteenth centuries.
The past is more relevant than ever to the future!