While writing my post on Ecological Footprint I came across a lot of sound arguments against it, but, to be fair, also a few less convincing ones. Here are two that hold more than a grain of truth, but simply will not convince the EF's proponents.
"Land prices will stop you from sequestering carbon"
The argument goes like this: it's unrealistic to assume all carbon emissions are mitigated by planting trees, because as more and more land is covered by 'carbon farms' (yes, not only the term exists, so does the practice), land will become so expensive that you will resort to other ways of climate change mitigation.
Of course you would expect land prices aree extremely high when the last square meter of agricultural land is converted to a carbon farm: after all, we only have one planet. But perhaps that is exactly what EF tries to tell us? Nevertheless, the argument points towards another problem with EF: it assumes sequestration is the only way to deal with GHG emissions, or at least the cheapest way. But although adaptation to climate change has long been a dirty word in the climate debate, it would be bad science and bad policy to dismiss it straight away - especially if sequestering carbon becomes prohibitively expensive. Given the choice between starvation and building better coastal defenses, my motto would certainly not be let em eat tree bark.
"You can overshoot temporarily without wrecking the planet"
EF counts any policy that increases stocks of carbon as unsustainable, but it is possible to accept a slight, temporary increase in carbon stocks without inflicting major damage to the climate system. Indeed, it might even be optimal to do so. If we could eradicate poverty by a temporary spurt in economic output to build up capital (read: build machines, infrastructure, establish institutions, etc), after which we close biophysical cycles again, bringing our impact on the planet within safe boundaries, the elevation to a higher but sustainable standard of living may more than offset the temporary damage inflicted on the environment.
But to me this sounds too much like the drunk who is caught by police while starting his car and tries defending himself with the excuse that he wasn't planning on actually driving it. Are you really trying to tell me that flying to distant holiday destinations several times a year (just to name an example) is supposed to be temporary, and to help developing countries get richer? Don't get me wrong here: I think everybody is free to take a long vacation on the other side of the globe if he or she likes, although we should do so facing prices that convey all relevant costs, and that includes our impact on the environment. But most people would assume that our current way of life is at least supposed to be maintained indefinitely, and otherwise to be expanded. The EF's proponents argue that this is impossible. There may be a lot to be said against their position, but claiming it's all meant to be temporary is not one of them.