About 56 million years ago, at the start of the Paleocene-Eocene Thermal Maximum, global temperatures rose by as much as 6 degrees Celsius. Researchers studying fossil leaves from southern Wyoming found that the dense forests there lost about 60% of their canopy as heat and drought killed many trees. Ferns briefly flourished, and then palms and warmth-loving plants spread north. The team reconstructed canopy density using the shapes of microscopic cells in fossil leaf cuticles, since leaves grown in shade develop longer cells. The forests did not decline gradually; they reached their densest point just before warming began, when rising carbon dioxide seemed to help growth. The canopy then remained much thinner for more than 100,000 years. Recovery came as rock weathering slowly pulled carbon from the air and cooled the climate. The authors note that today's carbon emissions are rising roughly 10 times faster than in the PETM.

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.