Concrete is the most used human-made material on Earth and causes 5-8% of global CO2 emissions, almost all of it from cement, the glue that binds sand and gravel. Portland cement, the method used for two centuries, heats limestone to about 1400°C; the rock breaks down and releases carbon dioxide, and coal- or gas-fired kilns add more. A proven alternative is geopolymer concrete, which swaps limestone cement for industrial byproducts such as fly ash and blast-furnace slag, activated with alkaline chemicals like sodium hydroxide. It can cut emissions by up to 80%. Queensland's Wellcamp Airport used about 40,000 cubic metres of it in 2014, yet it has barely spread since.

Indonesian Vice President Gibran Rakabuming Raka handed his resignation to parliament after questions were raised about his eligibility for office and his academic credentials. Gibran is the son of former president Joko Widodo, and his resignation came as Widodo publicly backed the president, Prabowo Subianto. Gibran had been elected vice president in 2024 as Prabowo's running mate. His candidacy was made possible by a 2023 Constitutional Court ruling on the minimum age for candidates, which was itself controversial. Parliament will now consider the resignation.

Angkor, near Siem Reap in northern Cambodia, was the capital of the Khmer Empire, which ruled much of mainland Southeast Asia between roughly the 9th and 15th centuries. At its height the city spread across about 3,000 square kilometres, making it the largest pre-industrial city on Earth by area. Its growth depended on water: huge reservoirs called barays, along with canals and embankments, stored monsoon rain and carried it to rice fields. That system let farmers harvest more than once a year and fed a very large population through the dry season. The temple complex of Angkor Wat, built in the early 12th century, is the best-known monument and still stands at the heart of the park.