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Season 2 Materials

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Activity Guide
TV Series Summary

Around the globe, scientists are racing to solve a series of mysteries: how could a one degree rise in average temperature have such profound effects? What happens to an ecosystem when top predators disappear? Why do invasive species cause such havoc? National Geographic’s Strange Days on Planet Earth, hosted by Award-winning actor, writer and director Edward Norton (Primal Fear, American History X, Italian Job), uses engaging storytelling and innovative imaging to explore new discoveries about the health of the planet.

Each of the four one-hour episodes (Invaders, The One Degree Factor, Predators and Troubled Waters) is constructed as a high-tech detective story. With the fate of the planet at stake, the episodes reveal the way seemingly distant events are connected and ultimately how they are affecting our individual health and well being.


Alien species of plants and animals have invaded every continent. They have enormous powers; they spread disease; they devour our buildings. Some are destroying the very land under our feet. Think of them as the first wave of an assault that could drive the greatest mass extinction since the end of the dinosaurs. What is causing this invasion, and what can we do to stop the rising tide?

Act I: They’re Here

Length: 5 min 43 sec

Starting Image: Wharf with fishing boats

Ending Image: Anemone in pet shop tank

Strange transformations are taking place around the world due to alien invaders: Jim Carlton is discovering marine invaders along our coastal shores; David Duffy and Greg Asner are fighting plant invaders in the lush forests of Hawaii; James Ogwang is battling more plant invaders and disease vectors in Lake Victoria while Claudia Riegel is attempting to save New Orleans from an implacable introduced horde of ravenous subterranean termites.

James Carlton introduces us to the growing worldwide problem of alien invasions and shares how he first developed his passion for this subject.

Act II: Impact: Property

Length: 11 min 15 sec

Starting Image: Riverboat in New Orleans

Ending Image: Norton in lawn chair

People in New Orleans no longer trust the floor beneath their feet. Their houses are collapsing, under siege by voracious alien termite hordes from China. Scientists, like Claudia Riegel, suspect these animals began their journey when American troops packed up to return home from WW II using crates from local Chinese wood.

Riegel is now working to slow down these beasts by exploiting their sociality. Using bait stations buried in locations across the city, she replaces wood bait with poison-soaked paper. Workers carry it back to colony headquarters and in as little as three months, their nests could be destroyed.

Act III: Impact: Health

Length: 14 min

Starting Image: Water of Lake Victoria, Uganda

Ending Image: Norton in lawn chair

Lake Victoria is the world’s largest tropical lake. It is also infamous for some of the world’s most devastating alien invasions — e.g. the loss of hundreds of specialized endemic cichlid fish species due to the introduction of Nile perch.

Today, another alien interloper may be jeopardizing the health of people living nearby. The disease schistosomiasis has been on the rise and scientists, like James Ogwang, suspect alien water hyacinth plant is partly to blame. Ogwang tests a way to fight the invader using biocontrol and importing the plant’s natural enemies — 1,200 weevils from South America.

Biocontrol is tricky business however and scientists can attest to some spectacular failures. For example, in the South Pacific, monitor lizards were unwisely introduced to an island overrun with invasive rats. The lizards opted for the islanders’ poultry supply so cane toads were brought in to temper the reptiles’ appetites. These toads are poisonous however so they ended up killing the lizards, multiplying and then killing the local cats — leading eventually to even more unwelcome rats.

Ogwang hopes for a different result. Making sure the imported weevils do not have a taste for local crops, his team breeds a weevil army and releases it. In short order, the army eats and depletes the hyacinth.

In many other places, people are still struggling with invasives, from Asian tiger mosquitoes to fire ants, killer bees, brown tree snakes and more.

Act IV: Impact: Soil

Length: 11 min 36 sec

Starting Image: Storm cloud time-lapse

Ending Image: Norton in lawn chair

In Hawai’i, botanists, like David Duffy, are tracking a plant called Miconia that left its native Mexico on a ship bound for Europe in the mid-1800s. In 1961, a botanical garden in Hawai’i welcomed Miconia as a gift. The species soon escaped from backyards, facilitated by another introduced species, the Japanese white-eye, a bird that excels at spreading seeds.

Forty years later, the invasive plant has spread over 10,000 acres on the Big Island and is shading out the native species. In its takeover, Miconia replaces the natives’ deep roots with its own shallow root system, placing the steep slopes of Hawai’i at grave risk of landslides. To combat Miconia, researchers, like Greg Asner, use state-of-the-art detection devices to map its growth in forests then uproot the plant, region by region.

On Hawai’i, concerned volunteers are helping Duffy to control the spread of Miconia. And around the world volunteer efforts are making progress on this vital issue.

Act V: Impact: The Biosphere

Length: 6 min 40 sec

Starting Image: Golden Gate Bridge, ship

Ending Image: Boy looking at fossil

At the bustling port of Oakland, Jim Carlton surveys massive amounts of cargo that stream into and out of San Francisco Bay on a daily basis — twice what was transported twenty years ago. Thousands of gallons of ballast water inside the hulls of cargo ships are one major way aliens infiltrate such ports. Carlton continues his survey of coastal invasions by inspecting plates that have been underwater for up to two years. By weight, 99% of the marine life in San Francisco Bay, now comes from somewhere else.

With the growing ship and plane traffic, eventually, almost everything will have a chance to move everywhere. Fully interconnected, researchers believe Earth will support far fewer species. Worldwide, invasive species are already the second greatest cause of extinction behind habitat destruction.


Length: 1 min 28 sec

Starting Image: Red wagon wheels

Ending image: Girl with pig in a wagon on road

Will the great reshuffling continue unabated? What is it worth … to be more cautious in our individual actions as travelers and consumers … to be more cautious as societies watching over the vehicles and vessels that tie us together? What will it cost not to?


Detectives usually break mysterious cases when they first see the connections among seemingly unrelated clues. Consider these: Dust clouds are building high over the Atlantic. An entire population of caribou is declining, their numbers dwindling, while in the oceans, other species are being pushed to the limits of their physical survival. A respiratory illness, once uncommon among children in Trinidad, is now widespread. Amazingly, many scientists now believe these disparate phenomena may be linked to global climate change.

Act I: Hot Times in the Far North

Length: 17 min 11 sec

Starting Image: Brooks Range

Ending Image: Norton dissolves on highway overpass

From the Arctic north to the tropical isles of the Caribbean, scientists like Steve Arthur from Alaska Department of Fish and Game, are documenting a series of perplexing phenomena that many believe is linked to climate change.

As heat accumulates in the global climate system, Alaska and the northwest corner of Canada are warming by as much as 11 degrees Fahrenheit. Emerging signs indicate that the region’s rising temperature is affecting the indigenous Porcupine River caribou. For decades, researchers, like Arthur, have been tracking the rise and fall of the caribou population — taking aerial photographs and counting numbers of animals. While their numbers have varied over the years, recent declines have caused some to question whether global climate change will impact the herd’s long-term survival. Longer summers in the region may mean a larger mosquito population, and these tiny tormenters feed on the caribou. To escape, the caribou seek out the cooler temperatures atop mountains and ridges, away from their traditional feeding grounds. The life of a caribou is a trade-off between time spent evading insects and time spent feeding or resting. The more time spent evading insects, the more energy expended and the less energy taken in by way of feeding.

Darius Elias, a member of the Gwich’n First Nation, also expresses his grave concerns that the dwindling caribou will have on his ancient culture and traditions.

Act II: Regime Change in the Pacific

Length: 6 min 30 sec

Starting Image: Sunset over the ocean

Ending Image: Zooplankton, net line in water

Biologists, Bill Peterson and his colleagues, sample nighttime populations of shrimp-like organisms, known as euphasiids, from a research vessel. These animals comprise the base of the ocean food web and fluctuate in response to a newly discovered long-term temperature pattern called the Pacific Decadal Oscillation. This oscillation is comprised of regime shifts where the ocean temperatures can shift several degrees from warm to cool. At present, the Pacific Ocean along the California and Oregon coast is in a cool phase. When the regime shifts back to a warm phase, with global warming riding atop this shift, certain regions of the ocean may reach a tipping point from which recovery will be extremely difficult.

Act III: Temperature Limits

Length: 6 min

Starting Image: Hopkins tidepool

Ending Image: Norton walks off camera

On the central Californian coast, physiologists, George Somero and Jonathon Stillman, are exploring how certain intertidal animals, like porcelain crabs, will or will not be able to cope with rising atmospheric temperatures. They are finding that some of these crabs are already operating extremely close to their physiologic thermal limit.

Act IV: A Tale of Connections

Length: 13 min 16 sec

Starting Image: Maracas Beach with kids playing

Ending Image: Sun beyond the air sample station

In Trinidad, Michele Montiel and her team are investigating how African dust is a prime suspect behind rising rates of childhood asthma. At the same time, in the U.S. Virgin Islands, scientists like Ginger Garrison, are examining possible connections between airborne African dust and a sea fan disease caused by the fungal pathogen Aspergillus.

Act V: Hurrell and the NAO (North Atlantic Oscillation)

Length: 5 min 37 sec

Starting Image: Boulder, Colorado-car on road

Ending Image: Kids on beach, Caribbean

Atmospheric modeler, Jim Hurrell is using global climate models to explore how all these events may be connected. He suggests that warming occurring in the Indian Ocean can send out an energy pulse that impacts an atmospheric phenomenon in the North Atlantic called the North Atlantic Oscillation (NAO) or Arctic Oscillation. The NAO is responsible for funneling weather towards northern regions of Europe and Eurasia. The NAO has been locked in a positive phase for several decades and may be influencing the strength of the tradewinds carrying African dust from the Chad region right into the Caribbean.


Length: 2 min 4 sec

Starting Image: Sun rise

Ending Image: Norton walks off camera

We have turned up the global thermostat with wide-ranging results. The choice is up to us as to how we want to deal with this problem.


Deep in the wilds of Venezuela, the natural order is being turned inside out. Miles of verdant forest and savannah have given way to small and scattered islands. Some of these islands are now overrun by bands of voracious howler monkeys, a glut of iguanas and hordes of ravenous ants. What is driving this bizarre transformation? A team of scientists believes that life here has run amok in large part because its top predators are gone. Similarly, the majestic wilderness of Yellowstone National Park is also showing signs of change that some scientists trace to the depletion of natural predators. Familiar and revered forests have vanished. Researchers are linking these forest losses to the expulsion of the gray wolf some seventy years ago. In Venezuela and around the world, experts are learning that predators seem to play a crucial role in the structure and function of entire ecosystems. When the predators disappear, the consequences can be dramatic. If predators are so vital, should they — and can they — be brought back?

Act I: Predator Loss at Lake Guri

Length: 13 min 49 sec

Starting Image: Boat in Caroni Valley

Ending Image: Close up on Norton’s face

Deep in the wilds of Venezuela, John Terborgh and his crew, including Cesar Aponte and Luis Balbas, are investigating miles of savanna and verdant forest that have given way to small, scattered islands. These islands were formed as a result of building dams for hydroelectric power plants. Some of these islands are now overrun by bands of howler monkeys, a glut of iguanas and hordes of ravenous ants. Terborgh and his crew believe life on these islands is running amok in large part because the top predators are gone.

Act II: Wolves and Aspen in Yellowstone

Length: 19 min 16 sec

Starting Image: Flyover Yellowstone Mountains

Ending Image: Lawn pool, toy shark

Meanwhile seminal aspen forests and willow groves are disappearing in the majestic wilderness of Yellowstone National Park. Scientists, like Bob Beschta, Bill Ripple and Eric Larsen, are investigating the landscape for clues. Measuring stream habitats and coring tree trunks they are finding clues that point to wolves.

Wolves were once a vital part of North American ecosystems before bounty hunters, starting at the turn of the century, decimated their numbers. The wolves literally reshape the landscape by instilling a primal fear in resident elk herd. It’s this fear that keeps the herds on the run so they spend less time intensively grazing on Yellowstone’s aspen and willow trees.

Following a controversial wolf reintroduction led by biologist Doug Smith, elk are now on the run in Yellowstone. Trees and shrubs are starting a comeback and nearby ranchers are learning to deal with their wild wolf neighbors.

Act III: Clues in Jamaica

Length: 9 min 52 sec

Starting Image: Water rush and shark approaches

Ending Image: Jamaica on map

In the Caribbean, once-vibrant coral reefs are under attack by insidious algae. With the reefs suffocating, scientists like Richard Aronson and Bill Precht take coral core samples to pinpoint when these problems arose. Other scientists, like Dan Pauly, are investigating the role that the loss of top predatory fish such as sharks, groupers and jacks have played in the reef’s slow demise. As these large fish were decimated by fisheries, smaller fish became the next commercial target — including those vital grazers that kept fast-growing algae in check. When those few remaining grazers in the over-fished reef were hit by disease, the algae were free to take over. The coral cores reveal that’s when the reefs really began to suffer.

Act IV: Restoration in St. Lucia

Length: 6 min 16 sec

Starting Image: Map of St. Lucia

Ending Image: Bird of prey lands on patio

Marine protected areas are providing places of hope. Biologists Satie Airame and Kai Wulf survey the fish life in the Soufriere Marine Management area in St. Lucia, Caribbean. Around these waters, there are no-take zones called marine reserves as well as managed fishing areas. Fishermen like Edward Mongroo are already heralding positive changes to their fishing operations traceable to the establishment of such regulated regions.


Length: 1 min 30 sec

Starting Image: Timelapse: street scene

Ending Image: Jaguar stalking

For centuries we’ve battled predators. Now we’re beginning to realize can we or do we really want to live without them?


In the American heartland, there have been strange disappearances. Frogs are vanishing without a trace. Further north, in the green waters of Canada’s St. Lawrence River, beluga whales are mysteriously dying — their white corpses found washed up on the stony shores. A world away on the Great Barrier Reef, swarms of monstrous sea stars are overrunning this marine paradise. At first glance, these stories seem unrelated. But, in fact, scientists suspect they may be part of a worldwide transformation brought on by toxins in the water. Have Earth’s vibrant waterways become massive delivery systems for invisible poisons? And are some of these poisons reaching our faucets? As scientists verify that our problem with toxins is mounting, cutting-edge research using plants and bacteria draw on the building blocks of life itself as a solution to problems vexing the planet.

Act I: Hayes and the Frogs

Length: 12 min 30 sec

Starting Image: Van on the road

Ending Image: Norton with water glass

Around the world, at least twenty frog species have become extinct, and many surviving populations are dying out. Biologist Tyrone Hayes and his students are studying Northern Leopard frogs in the American heartland and finding strange anomalies in these amphibian’s reproductive organs. Males have eggs in their testes.

At the same time, U.S. farms are producing about one trillion ears of corn every year often using manmade chemicals like Atrazine, which infiltrate the world’s waterways by way of wind and rain. Hayes’s research suggests that even tiny amounts of this Atrazine may be behind the reproductive problems of the frogs.

Act II: Toxic Belugas

Length: 8 min 8 sec

Starting Image: Globe animation

Ending Image: Kids and beluga tank

Farther north in the waters of Canada’s St. Lawrence River, biologists, like Robert Michaud, have discovered pods of beluga whales with some of the highest cancer rates of any wild animals studied. Dozens of chemicals have been discovered in the bodies of these whales. Some dead belugas are so full of toxins and chemical mixtures that they technically qualify as hazardous waste.

It’s these chemical mixtures, as opposed to any one toxin in particular, that are causing scientists, like Sylvain DeGuise, to worry. DeGuise is testing chemical combinations and finding that these cocktails can have a wide range of unexpected effects on developing immune cells.

Act III: Swan and the Sperm

Length: 6 min 48 sec

Starting Image: Meagher casts into pond

Ending Image: Norton in dry Los Angeles road

Epidemiologists like Shanna Swan, are investigating the effects of chemicals on humans. Swan and her team have reported high miscarriage rates in women who drink tap water with elevated levels of chlorine by-products. Now they are examining the reproductive health of men in cities like New York, Minneapolis and Los Angeles, versus farm areas like rural Columbia, Missouri. To their surprise, they are discovering lower sperm counts in rural areas where exposure to farming chemicals through tap water is more likely.

Farm chemicals aren’t the only places where chemicals can get into our water supplies. Hundreds if not thousands of man-made chemicals are found in the food we eat, in our carpets, fabrics and detergents and in our cosmetics.

Act IV: Meagher, Mercury and Phytoremediation

Length: 6 min 25 sec

Starting Image: Meagher casts into pond

Ending Image: Norton in dry LA River

Frustrated by mercury contaminating the fish in nearby lakes around his Georgia home, Richard Meagher is using genetic technology to enhance the clean-up capabilities of plants. Inserting bacterial genes into plants, he is a pioneer in the field of phytoremediation.

Act V: Coastal Systems and the Oceans

Length: 15 min, 18 sec

Starting Image: Tractor in Queensland

Ending Image: Boat on Ocean

In recent years, repeated massive outbreaks of Crown of Thorns Starfish have been destroying large parts of the Great Barrier Reef. Some scientists, like Katharina Fabricius, are investigating whether or not nitrogen-rich agricultural runoff could be a culprit. By tracking nitrogen plumes from river mouths, she and her colleagues are discovering that higher nitrogen levels do indeed correlate with higher larval starfish survival rates leading to potential outbreak conditions.

Sugarcane farmer Vince Vitale is concerned about the large amounts of fertilizer runoff from Queensland’s cane fields and manure from livestock ranches that are altering nitrogen levels in nearby rivers and river mouths. To stem the flow of nitrogen, he has given up acres of his cane fields in order to plant trees and restore a natural buffer zone between the cane fields and the rivers.

According to one school of thought, toxins appear to be diluted to safe levels by the time they reach the open ocean but is this hypothesis true? Marine biologist Tierney Thys and her team with the Census of Marine Life Project are tracking where open-ocean animals like the Mola mola (giant ocean sunfish) spend their time. Using new satellite tracking devices, they’re finding that open ocean animals spend a lot of time close to shore, in close proximity to where toxin-filled runoff enters the water. Fortunately, by pinpointing particular places where open-ocean species feed and breed we can better prioritize our clean-up efforts.


Length: 2 min 24 sec

Starting image: Boat on Ocean

The water that animals rely on is part of a single interconnected system-the same network that provides our drinking water. We all need to be more conscious and careful about what chemicals are entering our waterways.

Note to educators: Programs can be videotaped and used for up to one year after broadcast. Check your local TV listing or call your local public television station to confirm broadcast.

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