Permafrost is ground that stays below freezing for at least two years, and when the ice inside it melts, the surface can collapse. Thaw creates thermokarst ponds, and when these ponds suddenly drain, it signals that ice-rich permafrost has melted below. Researchers have mapped more than four million Arctic lakes, using aerial photos from the late 1940s and satellite images from the 1970s onward. They use artificial intelligence to scan new images for ponds that appear or disappear. The Seward and Baldwin peninsulas in northwestern Alaska are hot spots, where many large lakes have drained since the 2000s. Around 30 lakes drained in June and July 2026 alone. The team's near-real-time map helps communities identify ground unsuitable for building.

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.