Skies in Beijing were suspiciously blue on Monday on the eve of a National People’s Congress that will confirm Xi Jinping as China’s president. The authorities are adept at turning pollution on and off, often by the simple expedient of ordering factories to suspend production. Under Mr Xi, however, Beijing will have to move beyond the cosmetic. Pollution, of both air and water, risks becoming a grave political crisis as a better-informed public wakes up to the environmental catastrophe around it.

In January, Beijing disappeared for days on end beneath a blanket of foul smog, sending deaths from respiratory illnesses soaring. In recent years, there has been a series of mass protests against petrochemical factories in cities throughout China. Time and again, authorities have climbed down in the face of public anger against the threat of environmental degradation, which is now discussed obsessively online and on television.

To be fair, China has not stood still. Last year energy demand grew half as fast as economic output. Energy intensity has declined since about 2003 and China is a big spender on renewable technology. Yet rapid growth means pollution outpaces such improvement. China burns nearly half the world’s coal. By 2030, it is expected to have added more generation capacity than exists today in the entire US.