Here Peter Montague puts the pieces together, and still comes up with zero. This piece has been making the blog rounds of recent. Here's where his attempts at abstraction fail:
The U. S. Bureau of the Census estimates that global population will reach 9.4 billion by 2050, a 44% increase in 45 years. It might even grow faster than that, doubling in 35 years to 12 billion, but even 9 billion would surely stress the planet's already-stressed ecosystems mightily.But the world doesn't consume more with increases in population! Only an increase in that total population that subscribes to a high resource-consumptive lifestyle will increase the ecological impact upon Planet Earth to any significant degree... the only way to reverse humanity's "course" is to identify that specific course which humanity is following, aka NEOLIBERAL CAPITALISM, and that Montague fails to do.
Where will we put 44% more farms (with their fertilizers and pesticides and demand for fresh water), 44% more mines, more roads, highways, parking lots, airports, cars, trucks, buses, ships, trains, planes), more cities, hospitals, prisons, ports? And of course more wastes at every step.
Let's be specific, too, about the solution. Joel Kovel suggests in The Enemy of Nature that the production of commodities has to be replaced by "ecological production." This will require a whole new form of discipline, put in Foucauldian terms: capitalist discipline will have to be replaced by ecological discipline, the discipline of those who prioritize ecological stability before production is imposed upon the environment.
The imbalances created by neoliberal capitalism will not be corrected by substituting some other form of capitalist discipline for the market discipline imposed upon both labor and nature by neoliberal development. The capitalist system wormed its way out of the crises of the 1930s by instituting the managed growth of Keynesian macroeconomics. The current crises, economic and political and ecological, will not be resolved by more growth. Nor are the world's publics going to buy into the Ponzi scheme of a "capitalism without growth." In short, as capitalism was born, and as it aged through four leaps in capitalist discipline (from agricultural capitalism to factory capitalism to consumer capitalism to neoliberalism), so also it must die. Montague's statistics only reinforce my point.