Twenty years ago, the Stern Review on the economics of climate change reached a conclusion that surprised many: cutting greenhouse gas emissions would cost far less than living with the consequences of rising emissions. Launched in 2006 at the Royal Society with Tony Blair and Gordon Brown, it estimated that unchecked climate change could cost at least 5 percent of global output a year, against about 1 percent for action. Two decades later, renewable energy is cheaper and evidence on damage has grown, yet governments are still held back by political blockages, short election cycles and the problem of acting before costs are visible.

Hampi is a UNESCO World Heritage Site in Karnataka, India, with more than 1,600 surviving remains spread over 4,100 hectares. It was the capital of the Vijayanagara Empire from 1336 to 1565. Travellers from Persia and Portugal described it as a prosperous, wealthy and grand city with temples, markets and farms along the Tungabhadra River. By 1500 it was estimated to be the world's second-largest city after Beijing, and probably India's richest at the time. In 1565 a coalition of Muslim sultanates defeated the Vijayanagara Empire, its capital was conquered and destroyed, and the city was left in ruins. Hampi remains a religious centre, with the active Virupaksha Temple at its heart.