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American Samoa

Guam

U.S. Virgin Islands

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US & Territories

In this two-hour special, renowned paleontologist Kirk Johnson takes us on an epic adventure through time at the polar extremes of our planet. Following a trail of strange fossils found in all the wrong places—beech trees in Antarctica, hippo-like mammals in the Arctic—Johnson uncovers the bizarre history of the poles, from miles-high ice sheets to warm polar forests teeming with life. What caused such dramatic changes at the ends of the Earth? And what can the past reveal about our planet’s climate today—and in the future? (Premiered February 5, 2020)

Paleontologist Kirk Johnson explores the dynamic history—and future—of ice at the poles.

Polar Extremes

Something big is happening to Earth’s climate, and the polar regions hold the key to understanding it. Join top scientists on the hunt for clues that tell a surprising story about our planet’s past...and preview where we might be headed.

The Polar Lab

Disastrous hurricanes. Widespread droughts and wildfires. Withering heat. Extreme rainfall. It is hard not to conclude that something’s up with the weather, and many scientists agree. It’s the result of the weather machine itself—our climate—changing, becoming hotter and more erratic. In this two-hour documentary, NOVA will cut through the confusion around climate change. Why do scientists overwhelmingly agree that our climate is changing, and that human activity is causing it? How and when will it affect us through the weather we experience? And what will it take to bend the trajectory of planetary warming toward more benign outcomes? Join scientists around the world on a quest to better understand the workings of the weather and climate machine we call Earth, and discover how we can be resilient—even thrive—in the face of enormous change.

Discover how Earth’s intricate climate system is changing.

Decoding the Weather Machine

Mind of a Fossil Hunter

Dive into deep time to discover how fossils form, the ocean&#x27;s surprising origins, and more.

US, US Territories, Canada

Secrets of the Forest

Follow scientists in a quest to understand how complex forest ecosystems can help cool our planet.

This Asteroid Might Make Impact With Earth in 2032

An asteroid is on a collision course with Earth, possibly making impact in 2032. But there’s no cause for alarm: There’s about a 2% chance of impact, and that number may go down.
An asteroid is on a collision course with Earth, possibly making impact in 2032. In the unlikely event that Asteroid 2024 YR does strike Earth, it would generate an explosion equal to nearly 8 million tons of TNT. That’s 500 times the power of the atomic bomb that was dropped on Hiroshima during WWII. But there’s no cause for alarm: Space agencies estimate there’s about a 2% chance of impact, and that number may go down. EDITORIAL NOTE: The calculations around the likelihood of the asteroid hitting Earth fluctuate over time. The initial calculation we&#x27;ve included in the video was the prediction at the time of publication on February 14, 2025.
This Asteroid Might Make Impact With Earth in 2032Published: February 21, 2025NARRATOR: An asteroid might be on a collision course to hit Earth in 2032… but what exactly are the odds of disaster? And is there anything we can do about it?Asteroid 2024 YR4 measures between 130 and 330 feet long. It was spotted during its orbit around the Sun traveling away from Earth in late December 2024 thanks to ATLAS, a four telescope alert system that identifies near-Earth objects.Space agencies estimate that there’s about a 2% chance that the asteroid will hit Earth in December 2032. But as astronomers continue to track the asteroid and refine their calculations, they say that probability is likely to drop to zero.After astronomers discovered the asteroid Apophis in 2004, they calculated it had about a 2.7% chance of colliding with Earth. But after months of observations, scientists were able to update their predictions. They determined that it’ll pass very close to Earth in 2029 but the chances of collision are now zero. They expect the same thing to happen with asteroid 2024 YR4.In the unlikely event that 2024YR4 does strike Earth, it would impact at a speed of around 38,000 miles per hour and generate an explosion equal to nearly 8 million tons of TNT. That’s 500 times the power of the atomic bomb that was dropped on Hiroshima during WWII.It wouldn’t be big enough to kickstart a mass extinction like the one that led to the end of the dinosaurs — that asteroid was about 150 to 250 times larger. But it would have the potential to destroy a city — or if it lands in the ocean, which scientists think is more likely, the resulting tsunami could devastate nearby coasts.The damage from the explosion on land could extend roughly as far as a 30-mile radius from the impact site. NASA astronomers have come up with a “risk corridor,” an area where impact would be most likely given the asteroid’s current path. This area goes from northern South America, across the Atlantic Ocean to Africa, the Arabian Sea and southern Asia.As the asteroid continues on its orbit around the Sun, it’ll begin to fade from view of Earth-based telescopes by mid-April 2025. It won’t be visible again until mid-2028 — at which point astronomers will be able to calculate a more accurate trajectory.But what if the likelihood of impact goes up and not down as astronomers predict, what then?In 2022, NASA successfully crashed a spacecraft into an asteroid to change its trajectory. Space agencies could try and do something similar with asteroid 2024 YR4 to change its collision course. This strategy is still experimental, but it’s a promising way to help defend our planet.Although astronomers think the risk of Asteroid 2024 YR4 actually hitting Earth is very low, it highlights a potential new trend. As telescopes and cameras have gotten better at finding objects wandering around the solar system, this type of warning will likely become more common. But don’t take that as a harbinger of doom — just because we’re better at detecting potentially hazardous asteroids doesn’t mean our risk is any greater.

An asteroid is on a collision course with Earth, possibly making impact in 2032. But there’s no cause for alarm: There’s about a 2% chance of impact, and that number may go down.

A map shows ocean circulation in the Gulf of Maine

Ocean Currents and the Unique Ecosystem of the Gulf of Maine

Learn how ocean currents influence the Gulf of Maine and explore how they are affected by climate change with these videos from Sea Change: Peril in the Gulf of Maine, a NOVA special presentation.

A man stands in front of a herd of cattle

Using Kelp to Reduce Methane Emissions from Cows

Learn how changing the diet of cattle can reduce greenhouse gas emissions with this video from Sea Change: Survival in the Gulf of Maine, a NOVA special presentation.

How Do Hurricanes Form?

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Few things beat a hurricane when it comes to showcasing nature’s fury. A hurricane’s gales alone can churn out about half as much energy as the global electrical generating capacity — not to mention the torrential flooding it leaves in its wake. But before a hurricane can grow to such a beastly size, its birth first requires a specific set of conditions.Hurricanes, which scientists call “tropical cyclones,” vary in name by region: they're hurricanes in the Atlantic and eastern Pacific, but cyclones and typhoons elsewhere.A tropical wave often kickstarts the whole process. These formations are not ocean waves, but instead an area of low atmospheric pressure that rolls off the African coast and moves westward through the tropics. They normally develop when hot air from the Sahara clashes with cooler, more humid air from the forested central Africa. Sometimes, thunderstorms follow.The next ingredient is warm ocean water. As the tropical wave travels over waters above 26.5°C (about 80°F), warm, moist air starts rising upwards. This movement means there’s less air left near the surface — in other words, lower air pressure. Air molecules move from high to low pressure as they look for the path of least resistance, and as they do, the air from nearby areas with higher air pressure rushes in. Then, the new air becomes warm and moist and rises too.
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Up in the sky, the water in the moist air cools off and condenses into clouds. The process releases heat, further powering the growing tempest. This happens over and over again until giant cumulonimbus clouds emerge. As long as winds near the top of the system are not too strong — which could scatter the structure of the blooming clouds — an epic storm will begin to brew. Once the storm’s winds exceed 74 mph, it’s officially a tropical cyclone.But why do hurricanes rotate? That’s due to something called the Coriolis effect. As Earth spins on its axis, an object on the equator must move much faster than an object by the poles. Rather than traveling in a straight line, winds coming to and from the poles are diverted. When different winds collide, they begin swirling. As a result, hurricanes spin clockwise in the Southern Hemisphere and counterclockwise in the Northern. In the center is the eye, an open area around which the rest of the storm rotates.As long as hurricanes have warm ocean water to feed on, they will continue to amass speed and strength. Once they hit land, they can dump many inches of rain, down trees, and trigger dangerous storm surges, until eventually, a lack of fuel on land causes the hurricane to finally splutter out.
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Warm ocean waters fuel some of the most violent storms on Earth.

Removing CO2 from the Atmosphere: Where Does It Go?

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About half of all the CO2 humans have ever emitted still hangs over our heads, literally. Since the Industrial Revolution began, that totals nearly 1,000 metric gigatons stuck in the atmosphere.Now, scientists are working around the clock to create all sorts of new, innovative technologies to suck that CO2 back down. The holy grail would be reversing it all: finding a way to remove as much CO2 from the atmosphere as we’ve put in.Direct air capture is one such sci-fi-esque method to literally pull CO2 right out of the air. Featured in the NOVA documentary “Can We Cool the Planet?”, Climeworks is a Swiss start-up specializing in this type of negative emissions technology. Their direct air capture technology uses filters with highly reactive chemicals called amines to catch even the smallest concentrations of CO2 from the air. After the filters are heated, the bonds are broken. Then, pure concentrated CO2 can be extracted, about three-quarters of the CO2 originally sucked in. But what do you do with it afterwards?
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One answer is to put the CO2 where it originally came from: right back into the ground. Basalt is one type of porous rock that readily bonds with CO2 over a time scale of centuries. But the Icelandic company CarbFix has found a way to shrink this timeline to less than two years. The key is to dissolve the gaseous CO2 into water. Then, the fizzy water is injected into basalt. Once inside the rock, the dissolved CO2 reacts with metals in basalt to form new solid minerals like calcium carbonate. Most importantly, the carbon can then stay inside the rock forever.But if the promise of negative emissions technologies sounds too good to be true, that’s because it partially is. As of now, it’s nearly impossible to scale them up to a meaningful amount. They’re too expensive and require too much energy for a favorable tradeoff. Unfortunately, there’s no giant vacuum that can hoover up all the fossil fuel emissions of the world just yet.
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To combat climate change, scientists are working to remove carbon dioxide from the atmosphere.

Topic: Planet Earth

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