Earth's greatest crime scene
Around 66 million years ago, western India was torn apart by one of the largest volcanic events in Earth's history. Over hundreds of thousands of years, fissure eruptions unleashed a staggering volume of basaltic lava, which today covers 500,000 square kilometers (200,000 sq mi). Originally, the lava may have covered 1.5 million square kilometers, an area half the size of modern India. The accumulated layers of solidified lava are in some places more than 2 kilometers (1.2 miles) thick, forming the step-like landscape that gives the Deccan Traps their name. The total volume of erupted material is estimated at 1 million cubic kilometers (240,000 cu mi).
This colossal outpouring of lava occurred in several pulses. High-precision dating using zircon crystals found in ash layers between the lava flows reveals the main eruptive phase began about 250,000 years before the mass extinction event. This phase, which accounted for about 80-90% of the total lava volume, continued for 750,000 years. The eruptions spewed immense quantities of sulfur dioxide and carbon dioxide into the atmosphere, causing climate shifts. The sulfurous gases likely caused a drop in global temperatures by about 2°C, leading to a "volcanic winter," while the carbon dioxide drove long-term greenhouse warming and ocean acidification.