All Full Episodes
All Video Clips
Saturday Apr 22 12/11c
David Letterman travels to India to find out how the world’s soon-to-be most populous country is going to expand its inadequate energy grid.
Watch a preview
Electricity is the transportation fuel of the future. Cars with small on-board generators, advanced batteries or tanks of hydrogen will one day be as plentiful as gasoline vehicles are today.
With species disappearing so fast due to human activities, it’s said the world is entering a sixth mass extinction.
From sharks' ability to sniff out food to how well clownfish see, acidification poses grave risks to life beyond shellfish and coral.
Watch your favorite National Geographic Channel shows the day after they air.