Glacier Meltdown

Imagine a world where melting ice caps have raised sea levels by 20 feet and where great coastal cities could be under water. It is a worst-case scenario, but what is the scientific basis for the panic surrounding sea-level rise? Now, National Geographic separates fact from fiction to discover the real science behind climate change, the melting ice caps and why the intensity of tropical storms has increased by 50% in the past 30 years.