In the wake of the Volkswagen emissions-testing scandal (see Nature http://doi.org/723; 2015), this month's climate summit in Paris needs to roll out an international framework for regulating emissions — with strong incentives and tough penalties. Voluntary national measures are no longer enough.

Volkswagen's gaming of emissions testing underscores the urgency of reinventing transport. Governments must implement electric transport systems and plan for combustion-free inner cities, by expanding such schemes as London's ultralow-emission zone, due in 2020. Chancellor Angela Merkel could fast-track zero-emission zones for Berlin, Hamburg, Munich and Frankfurt by 2025, for example — restoring Germany's environmental lead.

The Volkswagen debacle should be treated as an Enron moment for sustainability measurement and valuation, with a comparable overhaul of the requirements for corporate accounting and evaluation. Programmes such as the Redefining Value initiative of the World Business Council for Sustainable Development can capture environmental externalities, including impacts on climate, biodiversity and health. Now we just need governments to incorporate these into their regulatory and stock-market requirements.