Why renewables are not enough in global warming fight

By mid-century, the world can build a zero-carbon electricity system as broader changes to the global energy system are needed, writes Ajay Mathur.

At the United Nations in New York on April 22, world leaders ratified the global climate agreement reached in Paris last December. One hundred ninety-five countries, ranging from richest to poorest, have now agreed to limit global warming to well below 2°C above pre- industrial levels, with the goal of not exceeding 1.5°C.

They have also committed to intended nationally determined contributions (INDCs) to limit or reduce greenhouse-gas emissions by 2030. But this is far from sufficient.