Watch NOVAs

Arctic Dinosaurs (Oct. 2008)

Experts in Alaska investigate how dinosaurs managed to thrive in polar regions. Watch now (50 mins.)

The Big Energy Gamble (Jan. 2009)

Can California's ambitious plan to cut greenhouse gases actually succeed? Watch now (50 mins.)

Booming Sands (Jan. 2005)

Scientists look into a generations-old conundrum: how and why do certain sand dunes produce mysterious noises? Watch now (7 mins.)

Diamond Factory (June 2009)

Visit a laboratory where entrepreneurs are growing perfectly pure diamonds. Watch now (15 mins.)

Dinosaur Plague (July 2009)

Insects caught in amber spark a controversial theory about what killed the dinosaurs. Watch now (15 mins.)

Extreme Ice (Mar. 2009)

An acclaimed photographer teams up with scientists to document the runaway melting of arctic glaciers. Watch now (50 mins.)

Fastest Glacier (July 2005)

A glacier moving way too fast reveals how unpredictable the effects of global warming can be. Watch now (7 mins.)

Hurricane Katrina (Oct. 2005)

Scientists' warnings proved sadly prescient about New Orleans' risk from hurricanes. Watch now (4 mins.)

Hurricanes (Jan. 2005)

Predicting a hurricane's intensity is notoriously difficult, but new tools may make it easier. Watch now (12 mins.)

Megabeasts' Sudden Death (Mar. 2009)

Scientists propose a radical new idea of what killed off mammoths and other large animals at the end of the Ice Age. Watch now (50 mins.)

Lightning (Oct. 2005)

Experts still aren't sure what triggers it, but they suspect cosmic rays from outer space. Watch now (9 mins.)

Mass Extinction (Nov. 2006)

What caused the mother of all extinctions 250 million years ago? Watch now (13 mins.)

Profile: Lonnie Thompson (July 2009)

A climatologist struggles to save ancient history preserved in ice that is now melting. Watch now (15 mins.)

Secrets in the Salt (July 2009)

Salt deposits that formed 250 million years ago hold tantalizing hints of early life. Watch now (15 mins.)

Storm That Drowned a City (Nov. 2005)

Experts and eyewitnesses reconstruct the devastating floods that Hurricane Katrina unleashed on New Orleans. Watch now (49 mins.)

Stronger Hurricanes (Jan. 2006)

Is global warming making hurricanes more intense? Watch now (6 mins.)