Will the global efforts to combat climate change be effective? Last week, Shell published its “Sky scenario” — a projection of how the risks could be averted through a combination of radical policy measures and the deployment of disruptive technologies.

But “could” and “will” are far apart. Energy policy is still a national responsibility with no legally enforceable international treaties — the Paris agreement is just a list of national pledges that may or may not be fulfilled.

Success or failure, therefore, comes down to the decisions made in a small number of key countries. None is more important than India. The future of the climate will not be shaped by actions taken in Paris or London or even Washington.