A Malthusian Scenario refers to humanity returning to an subsistence-level of existence due to population growth outpacing available resources. Originally the theory only referred to anticipated food scarcity caused by inadequate agricultural production, however “Malthusian Scenarios” now encompass the scarcity of any resource (in relation to an expanding population) that is key to maintaining society’s infrastructure.
When Malthus made his original projections his mathematical model made no allowances for improved technology or for incentives in the economic market being created due to there being a larger population.
However, the problem is exacerbated by economic growth in the developing world as this creates a populous that want to consumer more resulting in resources depleting even faster.
Whilst food production has expanded in the developed world, its sustainability could be jeopardized due to resources such as oil (which agriculture is heavily dependent upon) being rapidly depleted. If population continues to grow a Malthusian catastrophe would appear to be inevitable as there will always be a finite amount of resources from which we can make use.
Robin Hanson has also suggested that Singularity-level technology, such as mind-uploading, would possibly result in economic Malthusian scenarios where all wages would be reduced to upload subsistence levels.