It was the strongest cyclone to hit land in recorded history. On November 8, 2013, Typhoon Haiyan slammed into the Philippines, whipping the low-lying and densely-populated islands with 200 mph winds and sending a two-story-high storm surge flooding into homes, schools, and hospitals. It wiped villages off the map and devastated cities, including the hard-hit provincial capital Tacloban. Estimates count more than 5,000 dead and millions homeless. What made Haiyan so destructive? Meteorologists charged with tracking Pacific storms reveal why the Pacific is such fertile ground for cyclones, and NOVA’s film crew documents how conditions dramatically deteriorated in the storm’s aftermath, as impassable roads and shuttered gas stations paralyzed the critical relief effort, leaving food, water, and medicine to pile up at the airport. Disaster preparedness experts scramble to understand why the Philippines was so vulnerable. As climate change and sea level rise threaten millions of the world’