Green hydrogen is made by splitting water with renewable electricity, and it could cut emissions from steel, chemicals, shipping and aviation. Europe wants North Africa to supply it, since Morocco, Algeria and Egypt have strong sun and wind. The catch is water: making hydrogen consumes large amounts, and the sunniest, windiest places are also among the driest. Producing it for export would strain scarce supplies, and desalinating seawater to fill the gap puts brine and chemicals back into coastal waters, with consequences for marine life.

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.