A major challenge facing the sustainability movement is how to account for corporations’ positive and negative externalities — that is, the impact companies have on the wider world that doesn’t show up in traditional financial accounting. For business leaders, understanding these impacts is crucial as stakeholders, including investors, consumers, and regulators, increasingly demand transparency and accountability regarding a company’s larger footprint. When it comes to environmental sustainability, particularly, the need to measure and value nature accurately is becoming integral to strategic decision making, risk management, and long-term planning.