Earth's climate has slowly fluctuated between cold and hot periods for millions of years. Today, humans are greatly accelerating that process.

Over its history, Earth has fluctuated between two climate states: Icehouses, with ice caps at at least one of the poles, and Hothouses, when there is no ice at the poles.

Think you know what the Arctic looked like during the Eocene Epoch? Play NOVA’s Polar Lab to find out: You might be surprised by the plants and animals that used to call it home.

Carbon dioxide is an odorless, invisible gas. If we could see that carbon as a solid material on the ground, that might change our perspective on the amount of carbon we emit into the atmosphere. Play NOVA’s Polar Lab to see what effects all that CO2 is having on our planet’s poles.

To illustrate how the coastline might look if Earth's climate continues to warm, paleontologist Kirk Johnson and geologist Maureen Raymo search for 3-million-year-old clams in a Virginia quarry miles offshore.

Paleontologist Kirk Johnson shows a group of high schoolers that plant species in Virginia used to be right at home near the North Pole.

Inhabiting the Ross Sea—as far south as McMurdo Sound—Weddell seals (Leptonychotes weddellii) have the most southerly distribution of any mammal on Earth. Scientists began studying a breeding population of Weddell seals in 1968 and quickly found out these pinnipeds don’t always have it easy.

Trees are living records of Earth’s climatic past. Play NOVA’s Polar Lab to learn how trees grow by simulating how they respond to different environments.

In the premiere episode of Antarctic Extremes, join hosts Caitlin Saks and Arlo Pérez as they follow in the footsteps of the brave scientists that have made McMurdo Station, an otherworldly Antarctic outpost, their research base and their second home. Five days, 12,000 miles, and seven time zones with hundreds of pounds of camera gear in tow, Caitlin and Arlo go on a mind-boggling journey.

Researchers use camera traps in a Brazilian rainforest to capture a day-in-the-life of Alex the armadillo.

How do you study an animal you can't even get close to? Camera traps and drones are revolutionizing wildlife biology by recording the secret lives of animals—from whales and tigers to elusive giant armadillos—all without disturbing them.

Five experts weigh in on the complexities of measuring violence.

Psychologist Karen Wynn runs an experiment to find out whether babies are born with a sense of morality.

Violence is all over the news. But some say we’re living in the most peaceful time in history. Journey through time and the human mind to investigate whether—and how—violence has declined. And witness how people are working to stop violence today.

The Milgram Shock Experiment suggests that when an authority figure makes an order, even if seemingly violent, most people will carry it through.

Modern-day anatomy experts find inspiration in drawings from Leonardo da Vinci’s cadaveric dissections. But they also recognize what he got wrong.

Leonardo da Vinci was a Renaissance genius. Not only did he paint masterpieces of art, but he was an obsessive scientist and inventor, dreaming up complex machines centuries ahead of his time, including parachutes, armored tanks, hang gliders, and robots. On the 500th anniversary of Leonardo’s death, with the help of biographer Walter Isaacson, NOVA investigates the secrets of Leonardo’s success.