In response to that, the Planetary CFO is likely to want to evaluate many different units of measure for the balance sheet. We choose a unit of measure that means something to us. If the GBP or the USD have some latent meaning that is unhelpful, what about an alternative? Suppose we use as the unit of measurement the amount of sustainably managed land that supports an average global citizen for one year. We could call that unit the Global Sustainable Unit or GSU. Imagine a balance sheet where the assets side totals, say, 7 billion GSU, and the liabilities side totals a commitment to provide sustainably for 7 billion people. The balance sheet would balance. The challenge would then be to keep it balanced by protecting, maintaining and cherishing those assets so that they continued to meet the needs of a sustainable level of global population (eg at peak population).
Of course we know that we’re not at that point yet. We don’t even have a world balance sheet yet, but the Planetary CFO thinks it’s a pretty safe bet that when we create the first one, there will be an imbalance. The assets, whatever unit of measure we use to record them, will be less than needed. Probably, the liabilities will be about 1.4 times the assets, which would roughly correspond to the 1.4 planets that most people are saying would be required to support the current global population at the rate we use its resources.