Transcription
Times of turbulent weather are making us all too aware of the powers of nature. Sometimes we feel its force through natural disasters. But every day, the world's tested by nature's might.
Whether in the tropics of India or the mountains of the Andes, weather sweeps across the planet and can transform it at astonishing speed. And sometimes, even the Earth itself seems to fight back. Despite the challenges, nature endures. Animals have adapted to cope, and so can we.
This is the story of how water rules our world. Earth's a blue planet. It's 70% water. As it moves around the globe and through our atmosphere, it changes the weather, shapes the land, and impacts all living things.
Most of the water circles the world's oceans because of the spin of the Earth. The waters in a giant centrifuge, pulling it one way, while the moon's gravitational pull tugs it in the opposite direction, making it bulge on both sides of the planet, creating the rising and falling tides. A twice-daily pattern that has existed since the world began.
Winds dancing over the surface of the tide stir up waves. The stronger the wind, the bigger the waves. When the racing waves reached the shore, the belly of the waves slowed by friction with the sea floor and the water above it rolls forward. The wave breaks, creating dramatic sculptures in the rock as it eats away at them.
The timings of tides are predictable, but the force behind them is not. And right now, we are feeling this full force. Natural cycles like El Nino and the Atlantic multi-deadal oscillation pack more punch, but humans are also stirring things up. Climate change is raising sea levels and temperatures. As the ocean warms, it gets fiercer. And we are clearly already seeing the results.
Plunging atmospheric pressure at the heart of the storm causes the oceans to swell, and huge surges can be driven ashore, pounding the coast. The highest sea surface temperatures have just been recorded and coincided with one of the worst hurricane seasons on record. Hurricanes are driven by warm sea surface temperatures, and the increased heat means more water being carried inland, increasing flooding.
What do these deadly changes mean to wildlife or us? It's a hostile environment, but many animals have adapted to the cold, salty, dark seas. Their lives are dictated by the same forces that sculpt our coast. The so-called 12 Apostles have been carved out of the limestone coast by the power of the Southern Ocean. The 45m columns are chipped away at by about 2cm a year, and all will eventually collapse under the force of the waves. But that same colossal force brings nutrient-rich water from the seabed in towards the shore. Where the cold but nutrient-rich seas hit the warm, sunny waters of the coast, life abounds.
Something Australian pelicans will fly many kilometers to exploit. At around 7 kilos, the pelicans are one of the world's heaviest flying birds. Using uplift, the wind deflected upward by the cliffs to help carry their weight. Their huge webbed feet act like water skis to prevent a crash landing. Australian pelicans have the longest beaks in the world, 50cm long. The lower jaw is flexible and can expand, allowing the throat pouch to fill up with water, creating a vacuum that drags fish in with it. But to make the feeding technique more effective, the birds organize themselves into a flotilla, swimming abreast, encircling the fish, driving them into one another's beaks. Pelican pack hunting.
But pelicans like an easy life. They prefer sheltered bays and estuaries. They'll occasionally take advantage of the rich, churning oceans, but stay close to the shore where they can dry off and do some maintenance alongside cormorants and other water birds. To cope with the ocean's fury, they must run a tight ship. Every feather must be oiled and weatherproofed. Most water birds produce oil from a specialized gland near the tail that they can spread over their bodies. It waterproofs them, giving rise to the saying, "Water off a duck's back."
Pelicans play it safe. It can be terrifying offshore, but there are hardier fishermen who face it head-on. Gulls have narrow wings, giving them great maneuverability over the waves. They can ride uplift from the waves themselves. As the water deflects wind upwards, it provides a free ride, saving their energy.
Saltwater is hard for any animal to deal with. Water. Water everywhere, but not a drop to drink. But gulls have overcome that challenge with their own portable desalination plants. Special glands above the eyes extract the salt and expel it through their nostrils. It means they can even drink seawater. They're clever and adaptable, using tricks like dropping shellfish on rocks to break their shells or mobbing passers-by for their fish and chips. It's hardly surprising that they've learned to follow fishing boats to pinch free meals. They learn by copying each other. So, it doesn't take long to attract a flock.
But in this tough landscape, animals must use every trick in the book to get by. One of the toughest environments on Earth is the tidal zone. Here, the force of waves face the resistance of rocks, smashing everything, churning in between. But animals and plants still make a living. Seaweeds have soft, tough-skinned bodies that can go with the flow, and they provide shelter and something to cling to for a multitude of invertebrates. Fish thrive despite the currents, but it's a very tough place for mammals to make a living. Still, some pioneers have conquered the treacherous waves.
Dolphins are found in all the world's oceans. Their torpedo-like bodies have become the ultimate in hydrodynamic design. But the bottlenose dolphin is a coastal specialist, boldly entering the fierce and unpredictable tidal zone. As the tide rises and falls, it drags nutrients from the shore and stirs it up into a nutritious soup that's consumed by plankton. In turn, feeding larger animals. This is a turbulent place to live. Creatures in the tidal zone risk being cast ashore or worse, bashed against the rocks. But for the bold, there are rich pickings.
As the tides turn and stir up silt, visibility is zero. But dolphins can see in the dark. Like bats, they use echolocation. Squeaks, whistles, and clicks made in the blowhole travel through their fatty foreheads where they're amplified and focused. These powerful sound waves go forwards, and the dolphins navigate by listening to the returning echoes. This can even help them locate tiny prey in the chaos of the seas. All life here, dictated by the tides. Coastal creatures feel the forces of nature every day. They live their life in two worlds.
As the tide retreats, dragged away by the movement of the moon, large areas of coast are exposed. Mudflats are rich in detritus, nutrients washed off the land, and bits of marine life washed in and stranded. It's a tempting feast, but it means that marine life must battle the elements. They must cope with being high and dry. The rocking back and forth of waves has sculpted the sand. And now it's left bare, exposed to the elements and will dry out. Mudflats and sandbars can be vast, revealed only at low tide. It's a habitat of two halves.
What looks like mounds of sand spaghetti are the spoil piles of burrowing lugworms. They sift the soggy sand for any organic matter and then spit it out. These cryptic, creepy crawlies can make up to 30% of the animal biomass on mudflats and yet are rarely seen. This one was evicted by the retreating tide, but will soon dig itself back into the sand.
While the ground's moist, winkles get to work grazing algae from the particles of sand. While they can weather the low tide, cockles prefer to keep things under wraps. They like to live just under the surface of the sand so they can filter moisture from overhead. Their preferred location leaves them vulnerable. Stormy waves can wash away whole cockle beds. But in the nutrient-rich top sand, it's worth the risk.
Crabs can spend some time scavenging on the beach, but they breathe through their gills, so periodically they must find a puddle and give them a good dunk. Not surprisingly, this bustling invertebrate community attracts seafood specialists. Wading birds use their long bills to probe the mud to catch shrimps and worms. They have pressure sensors on the end of their beaks so they can feel objects of different densities in the mud. Perfect for locating hidden invertebrates. There's plenty of food, and they flock to it. Wave after wave of them.
Some wading birds patrol a stretch of coast year-round, but others are migrants that stop in to refuel, taking on the fat reserves they'll need to make mammoth journeys. Some traveling over 10,000 km. Looking like airborne shells of fish, the so-called murmurations are designed to confuse predators, making it harder for them to pick out an individual from the swirling masses. Millions of birds spend their time tracking the tide up and down the beach. Without the turning of the tides exposing this transient landscape, such natural spectacles couldn't exist.
Once the mudflats have been exposed for hours and almost baked dry, and water-loving creatures have been pushed to their limits, then gradually the tide creeps back in. Dehydrated marine creatures are once again plunged into their challenging brine. The tide hides this productive and mysterious world, keeping it under wraps for hours until low tide returns. The daily patterns of the tide support the vast animal community. But there's a penalty. All face the constant threat of a storm, which can make their difficult lives deadly.
Storms can sweep across the ocean and batter the coast. They carve jagged features into the coastline and hide them beneath the rising waves. Deadly traps that bring ships to their grave. Lighthouses stand up to the storms, sending warnings across the waves. A human attempt at beating, or at least avoiding, some of nature's full fury. Though it's not always enough, as storms sweep across the coast. They can wreak havoc and can bring a lot of water with them, which will fall inland.
A tide of change sweeps across the landscape. The coming rains will bring great changes to the fortunes of wildlife. An average of about 1m of rain falls on every part of the Earth's surface annually, though of course, it doesn't fall evenly. Some areas hardly get any; others are drowned. Every year, the Earth receives enough water to fill the Empire State Building half a million times.
Warm weather leads to more evaporation, of course, enhanced by global warming. More evaporation means bigger, heavier clouds. Eventually, they get too heavy and burst. And the influx of water, both from the sky and flowing in from higher country, can cause rivers to burst their banks. And on baked earth, it gathers on the surface and can travel at speed. If the ground's already waterlogged, then the water levels quickly rise. So-called flash floods can bring more than 5m of water in less than 6 hours, dislodging millions from their homes, be they people or bugs.
In desperation, an ant colony flees, grabbing as many of their larval babies as they can, hoping to stay above the rising waters. 90% of natural disasters involve flooding. And it's not just wildlife that's affected. Annually, floods cause billions of dollars worth of damage and have more serious consequences. In 100 years, flooding has claimed more than 10,000 lives in the US alone. Survivors are left to clean up the mess. Apart from the obvious damage, floods also present a health threat, with the waters flushing out sewage and depositing the bodies of casualties, leaving them to rot.
Floods can be devastating to people and animals alike. The blind mole rat lives his life underground. But flushed from his burrow, he clings to a life raft and tries to dry off. Small animals have little choice other than going with the flow. As the forest floods, even larger creatures must flee. They congregate on higher ground, stranded, waiting for the water to recede.
But there is some small compensation for the disruption. Floods can carry nutrients from rivers and high ground into less productive areas. The nutrient-rich silt is deposited and improves soil fertility. This refreshing of the landscape was part of the success of the Egyptian Empire, as floods from the River Nile created rich farmland.
Though certain areas are more prone to flooding than others, flooding can occur anywhere. The Sonoran, home of the Saguaro cactus, icon of the desert. Cacti are associated with arid landscapes. They're designed to store liquid to survive their desolate home. But even they sometimes get watered. But dry desert soils don't drain well, and the landscape lacks watercourses that guide runoff in most areas. So rain that falls quickly builds. It's a relief to parched wildlife. A rattlesnake sips water from its body, making the most of the rare treat.
The Sonoran Desert doesn't get much rain, but what it does get can come at once. And with surprising ferocity. Late summer monsoon winds carry rain in from the Pacific and dump it on the desert. The storms are hard-hitting but short-lived. However, with nowhere to drain, the water builds. Water always finds the lowest place it can and gradually the flood seeps downhill into valleys where it can join rivers. In its wake, the desert blooms, offering its residents a rare period of abundance. The wet won't last, so animals are quick to make the most of it. Birds do it, bees do it. Everyone must cash in and fast. Including one of the desert's largest inhabitants, javelina, desert peccaries that are as happy as pigs in mud.
Even on the same continent of North America, there are regions where it barely rains and areas where it rains all the time. And here, animals must cope with constant wet. The Smoky Mountains get more rain than the rest of the Southeast United States combined, 152cm a year. But instead of a deluge, it's a constant drizzle. Fog makes up 60% of the annual rainfall. The residents here are used to working wet.
Black bears have long, glossy guard hairs that help the water run off without soaking into the fluffier undercoat beneath, the woolly jumpers that keep them warm on these cold, damp mornings. The reason their playground is so soggy is because the Smoky Mountains run parallel to the Atlantic coast. Storms bring in moisture from the sea, but when it hits the mountains, it's forced upwards into cooler air. Here, it condenses and drifts back down.
It's possible that there is more to it than just geography. The plants might be watering themselves. Plants produce aerosols, tiny volatile organic compounds released from their leaves which attract water. The trees can draw in their own miniature cloaks of fog. And a little fog can act like a magnet, drawing in more fog until the valleys are blanketed. It can make the high-rise work of bears a little treacherous. Luckily, their long claws and rubbery foot pads help them grip the slippery bark.
Chilly, foggy mornings bring challenges to others. Hummingbirds have very high metabolisms. Like a fighter jet, they burn fuel fast and must frequently refill. But cold and waterlogged, it's not always possible for them to feed. The minute birds have a get-out-of-jail card; they can enter a state of torpor, like a miniature hibernation. They slow down their metabolism and rest, waiting for the sun to come and dry them off. A trick bears seem to know, too.
Science is only just starting to understand the important role these so-called temperate rainforests have on the water table. When it rains hard, much of the water runs off the earth and into river systems. But the mist soaks in, seeping deep into the ground. It can recharge aquifers, vast underground reservoirs, sources of water tapped by plant roots and by people. The mist that soaks into the Smokies supplies 30 million people with water and provides a rich habitat for wildlife. The temperate rainforests are rare habitats, small areas geographically, but scattered across the globe. Wildlife here must learn to live wet.
Of course, rain and flooding are perfectly normal in some areas, and nowhere more so than the equatorial rainforest. The equator is the part of the Earth closest to the sun. It's hot year-round. It gets constant direct sunlight every day. This heat causes more evaporation and keeps the humidity high. And sometimes that airborne moisture comes back down to Earth. Rain might be the norm here, but not all the inhabitants seem to like it.
Sun and moisture result in spectacular plant productivity. Only 6% of the Earth's surface is hot and wet enough to support true rainforest, but they're globally important. 40% of the world's oxygen is made by the plants here. It would not be possible without the daily drenching. It can be hard work for all the rainforest's inhabitants. Water dictates life, and it brings opportunities and challenges.
40% of South America, all 7 million square kilometers of it, are blanketed by the Amazon rainforest. It could cover all of the lower 48 states of America. The region has two main seasons: wet and dry. The dry season's well, wet, hot, and humid. But in the wet season, the forest is transformed. The rainy season hits the Andes and other highland regions, and the water runs off, swelling the land rivers of the Amazon basin. This, combined with the Amazon's constant rainfall, transforms the landscape. Once again, wildlife feels the power of water.
The rivers burst their banks. 250,000 km are flooded. In places, the water rises by more than 12m, submerging the forest. For the creatures of the forest, it can be devastating, instantly sweeping away their homes. Fortunately, most of them can swim and have no choice other than to seek higher ground. Tortoises and armadillos are bulky but surprisingly agile in the water. Smaller creatures can't fight the currents, so ride it out.
But for the river creatures, all their Christmases have come at once. They're free to stroll around the tree canopy, rich in fruits and nuts that are normally way beyond their reach. Tannin leeches from leaves, turning the water into tea and concealing some deadly threats. Boto, the Amazon River Dolphin. These dolphins have poor eyesight, though it's no handicap. There isn't much to see in this giant cup of tea. They find their way and their food using echolocation, chasing fish through the forest. They're not the only mammals munching through the floodgates. Amazonian manatees, that usually must contend with aquatic plants, are now free to browse where they please. The return slow-moving sea cows munch through 8% of their body weight every day. The floods wash in nutrients from the surrounding areas and cleanse the forest, flushing out parasites from the leaf litter and helping to disperse seeds.
Weather shifts water around the globe, and repeated patterns are often mirrored in the life of animals. Many migrate either to escape bad weather or to benefit from the moisture it brings. Following the good weather, they get the best out of life. Traveling to productive feeding areas and the perfect places to raise their young. The Great Plains of Africa see one of the biggest shifts. Millions of tons of animals on the move, and all because of the rain. For much of the year, the plains are scorched. Animals use what little shade they can find to escape the fierce sun. But then the skies bring relief.
Not everyone's happy. Some creatures don't like getting their feet wet. The hard ground quickly waterlogged. Less than an hour ago, this was dry grassland, a safe place for the lioness to leave her cub. The cub's at risk of drowning or hypothermia, so she must wade in to retrieve him. The water that brings life can also threaten it. Fortunately, Mom finds him and can crane-lift him to safety. There's clear relief as the rain clouds lift.
But the rains are a blessing. The precious moisture will transform the plains. Lush green follows the rains, and an army is on the move to reach it. 1.5 million wildebeest perform a never-ending clockwise circular migration across 40,000 km of the Serengeti ecosystem. Following the fresh water means good food and drink for the masses, but it presents many challenges along the way. The endless trek ensures the herds move on before any one region gets overgrazed. It's a never-ending march, 1,000 km in every loop. But their quest brings them into enemy territory.
The rains bring abundance for everything. And for the hydrophobic lions, it's well worth putting up with occasional wet feet. Our planet's battered by the force of water, but also shaped and nurtured by it. It can be devastating, but also giving, creating new opportunities. There's no doubt we live in turbulent times. Climate change is cranking up the dial, and we're seeing weather at its worst. We try to fight the weather. Lighthouses try to guide ships and spare them some of the sea's fury. And we build sea defenses to protect our homes from the ocean's awesome power.
But more importantly, science is getting better at understanding weather and predicting it. If we understand weather systems, we can take evasive action, save lives. The world has survived many periods of warming and cooling and can do so again. And if we're wise to the changes, we can too. We can weather the storm.
Water is one of the greatest forces of nature. It's the key ingredient that makes Earth unique. It can devastate, drown landscapes, destroy homes, and wreck ships, but it also supports life. We're dependent on the forces of water. It enriches our lives and in more ways than one.