Global footprint network make the extraordinary proposition that the world's
> own ecological footprint is bigger than the world.
It's only "extraordinary" if you assume that a population is incapable of (temporarily) exceeding its own carrying capacity, which would be erroneous. (And at the risk of pedantry, we're talking about the ecological footprint of humanity, or portions thereof, not "the world.")
> So riddle me this? Why is the actual land area farmed and developed less
> than half the size of the 'ecological footprint'? In fact, the land area
> that the world's population actually uses has been shrinking since 1981, as
> cropland has reduced (because of higher yields).
>
> Wouldn't you expect the actual area harvested to grow as the 'ecological
> footprint' grows? How is it that the calculation tells us we need more land
> to feed our consumer society, but the actual land area we use is shrinking?
>
> The answer has to be that the calculation is wrong.
It's because agriculture, particularly in the industrial form which has enabled the efficiency you describe, requires the input of significant resources beyond the land used for cultivation, all of which take secondary tolls elsewhere. From the 2006 Living Planet Report, which describes footprint methodology:
"Agricultural technologies can boost productivity, but can also diminish biodiversity. Energy intensive agriculture and heavy reliance on fertilizer may increase yields, but at the cost of a larger footprint associated with increased inputs, and may so impoverish soil that yields ultimately begin to fall."
http://www.footprintnetwork.org/download.php?id=303
-- "Hige sceal þe heardra, heorte þe cenre, mod sceal þe mare, þe ure mægen lytlað."