The challenge of assessing future risks

It is evident that the ecological capital of our planet, composed of natural assets such as land, forests, rivers and oceans and even the air we breathe, is being systematically and relentlessly eroded, threatening the well-being, perhaps even the survival of future generations.  We are living on an ecological ‘overdraft’, which implies using the planet’s natural assets on a scale that is far beyond the capacity of nature replenishing them. While this appears to be patently obvious, why is it so difficult to implement policies to ensure ecological sustainability? The answer lies in the biases and gaps which are inherent in our system of accounting, which is the basis on which economic activities are evaluated and cost-benefit ratios are calculated.