Which metric is commonly used to assess a company's environmental performance?

The metric that is commonly used to assess a company's environmental performance is carbon emissions or greenhouse gas emissions. This is because these emissions directly quantify the impact a company's operations have on the environment. Tracking carbon emissions allows stakeholders to evaluate a company’s sustainability practices and its commitment to reducing its carbon footprint. An increase in carbon emissions may indicate poor environmental performance, while a decrease can signify effective strategies for reducing negative environmental impact.

Other metrics like net profit margin, return on investment, and market share primarily focus on financial performance rather than environmental impact. While financial success can contribute to a company's overall sustainability efforts, they do not provide direct insight into the company’s environmental practices or its effectiveness at minimizing environmental harm. This distinction is critical in understanding the importance of measuring a company's environmental performance specifically through metrics related to emission levels.