Environmental History
A new study reveals that repeated long droughts likely contributed to the slow fade of the Indus Valley Civilization around 5,000 to 3,500 years ago. Researchers reconstructed ancient climate patterns showing temperature rises and reduced rainfall that shifted settlements and led to deurbanization. The findings highlight how environmental pressures shaped one of the world's earliest urban societies.
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Researchers have pinpointed how trace levels of nickel and urea hindered the buildup of oxygen in Earth's atmosphere for over a billion years. Their experiments show these compounds limited cyanobacterial growth until conditions changed, triggering the Great Oxidation Event around 2.1 to 2.4 billion years ago. The findings offer insights into early Earth chemistry and potential biosignatures on other planets.