Podcast
EarthDate
Hosted by Switch Energy Alliance · EN
EarthDate is a short-format weekly audio program delivering concise, science-based stories about the Earth: its geology, environments, and the processes that shape our planet over deep time and today. Beginning in 2026, EarthDate is managed by Switch Energy Alliance and hosted by SEA's founder Dr. Scott W. Tinker. Together, we explore earth systems, natural resources, and their relevance to everyday life, with a focus on clear, accessible science education for broad audiences. EarthDate is written and directed by Emmy-winning filmmaker Harry Lynch, and researched by Lynn Kistler. We search for captivating stories to remind listeners that science can enlighten, educate and entertain.
129episodes
Episodes
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Lakes of Life
Jun 2900:02:00Tap to summarizeCharles Darwin proposed that life on Earth may have started in bodies of highly alkaline water called soda lakes. New research suggests he may have been right. You might remember from a prior EarthDate that phosphorus is an essential building block for DNA, RNA, and the energy carrier for cells, ATP. Without phosphorus, there is no life. Soda lakes are some of the few places on Earth where phosphorus is readily available, rather than bound up in rocks. Nearly all these lakes around the world are closed basins. Water enters, but there is no outlet. As rivers flow toward a soda lake, running water leaches minerals out of the rocks it passes over, notably calcium and phosphorus. These then concentrate in the lake. Normally, phosphorus would bond with dissolved carbonate compounds in the lake water and sink out. But calcium bonds more readily with carbonate than phosphorus, leaving the phosphorus in a pure form. Evaporation further concentrates it.In small soda lakes, the level of phosphorus rises and falls with the rains, and the amount of river inflow. But new studies on larger closed basins show that phosphorous concentrations can remain high year-round, indefinitely…
Transcribe →The Water and Energy Link
Jun 2900:02:00Tap to summarizeOur modern supplies of water and energy are miraculous – and tightly interlinked. Only 3% of Earth’s water is fresh. And 99% of that is frozen in glaciers or stuck underground. That means just 1% of fresh water is on the surface where we can easily access it – for agriculture, mining, industry and our consumption. To get that water to us requires energy. First it’s pumped, sometimes over long distances, from a reservoir or river to a water treatment plant. There, it’s filtered, purified and chlorinated. It then flows to our houses and factories. When we’re done with it, it goes into a wastewater treatment system, where it’s cleaned again and discharged. Because water is heavy, moving it through these processes can consume 40% of a city’s electricity. And to make all that energy requires – yes – water. Oil and gas wells use water, in drilling mud and to fracture rock. Coal, natural gas, and nuclear powerplants boil water into steam to turn a generator, while water cools the plant. The generators in hydroelectric dams turn under the power of water. Even solar farms use water, to wash their panels. Wind turbines don’t use water directly, but the factories and smelters that make their parts and steel certainly do. And to get them that water… takes energy. We rely entirely on both. And couldn’t have one without the other.
Transcribe →The Moth with Two Maps
Jun 2800:02:00Tap to summarizeThe giant bogong moth has a brain one-tenth the size of a grain of rice. And eyes the diameter of a human hair. Yet it can navigate by sensing the magnetic field of Earth. Or by gazing at the stars, reading a mental map that it was somehow born with. Each spring in Australia, they leave the lowlands by the millions, and fly at night over terrain they’ve never seen before, following their internal compass, and that inherited star map. They’re the only insects we know of that can navigate this way. And they’re all headed to the same place: the cool highlands of the Snowy Mountains, where they sleep away the summer heat in caves. Historically, they’ve been a keystone species here, with a disproportionately large effect on the ecosystem. Other animal populations have relied on their annual arrival for food. Aboriginal tribes used to gather in the mountains to harvest and roast moths. But the bogong has declined precipitously over the last decade. Rising temperatures and drought have reduced their food sources. Pesticides have reduced their numbers. Light pollution from towns and farms has reduced their ability to navigate.Conservation groups are trying to save the moth, but with so many stressors on their population, that’s hard to do. Let’s hope they’re successful, because the bogong moth is another overlooked example of the wonders of nature, its interconnectedness, and its vulnerability.
Transcribe →The Crystal Eye of Ninevek
Jun 2800:02:00Tap to summarizeDuring World War 2, an American pilot flying over the Canadian arctic saw something extraordinary. A midnight blue lake, 2 miles across, shaped in a perfect circle. The Allies kept it a secret, using the lake as a navigation landmark during the war. But in 1950, photos hit the media, and the lake became a sensation…because it shouldn’t exist. There were no rivers leading into it, and none leading out. There was not enough liquid groundwater in this frozen landscape to fill it. It was as if the lake had been dropped from the sky. And in fact, it had. Scientists soon determined it was formed by a huge meteorite. Its trajectory would have been straight down, striking Earth at 30,000 miles an hour, with the force of 8,000 Hiroshima bombs. It bored a hole more than 800 feet deep, and pushed up 500-foot high ridges around it, isolating it. Of course, the natives had known of the crater for centuries, calling it the Crystal Eye of Nunavik -- because it contains some of the clearest surface water on Earth. Research confirmed that the water came from melting Ice Age glaciers and is only recharged by melting snow and ice. With no rivers to bring in sediment, the soils on the lake bottom contain mostly dust, pollen and diatoms -- from millennia ago, preserved in the frigid water. In this way, the Crystal Eye literally lets scientists “see” into the distant past.
Transcribe →Chernobyl: Rebirth
Jun 2800:02:00Tap to summarizeAfter the Chernobyl nuclear accident, the Russian government declared a thousand square miles around it an exclusion zone. The hundred thousand people evacuated could never return to their homes. The wildlife, however, could. European bison, which had vanished from the area, returned and populations grew. So did native deer. These large herbivores brought large predators, like lynx, bear and especially wolves, which had been hunted to near extinction. Large birds of prey came back too – golden eagles, white tail eagles, black storks and owls. Along with wild boar, beavers and fish in ponds, and rodents of all sizes. Scientists thought it would take decades. But the diversity and density of animal populations quickly grew to levels of a nature preserve. Scientists did find some negative effects of the radiation, like cataracts in rodents, and mutated insects. And some adaptations. A tree frog that naturally has either green or brown skin, had developed nearly black skin – more melanin, which can absorb radiation. Yet, feral dogs showed no radiation-induced genetic damage. In fact, most animal populations showed increased radiation, but no mutation beyond normal genetic variance. The rebound of animal populations at Chernobyl is a study in the resilience of nature, and the surprisingly low impact of radiation upon it.
Transcribe →We Changed Horses
Jun 2800:02:00Tap to summarizeHorses changed human history. But first we had to change horses. The horse evolved in North America 50 million years ago, and migrated across the Bering land bridge into Eurasia. Then, during the last Ice Age, it went extinct in the Americas. Around 5,000 years ago, humans began taming horses in the Eurasian Steppe, in what is today Kazakhstan, Russia and Ukraine. There, archaeologists have found residue of mare’s milk in drinking vessels. Some horse skeletons show wear on their teeth suggesting they held bits in their mouth. But other skeletons have arrow points embedded in bones, suggesting that horses were hunted as much as domesticated. A thousand years later, a different steppe culture tamed a different horse and, evidence shows, developed a horse culture – so successfully that it replaced the earlier horses. Genetic testing revealed that this first domesticated breed, called DOM2, became the progenitor of all later horse breeds. With them, humans could travel farther and faster than ever before. Mounted nomads could cover landscapes. Mounted cavalry could vanquish enemies. Horses could pull carts, and later, plows. We hardly think about it today, but from 4,000 to just 100 years ago, horses were the driving force in human transportation, settlement and warfare. The only thing that moved more people was our own two feet.
Transcribe →Almost Atlantis
Jun 2600:02:00Tap to summarizeIn 2024, Spanish oceanographers studying the deep seafloor west of the Canary Islands discovered an enormous seamount -- A mile-high, 70-mile long mountain on the bottom of the ocean, formed of three inter-linked ancient volcanoes.At its summit, just 200 feet beneath the water’s surface, they found sand dunes and cliff faces that could only have been formed if it had once been above water.During the last Ice Age, when Earth’s water was locked up in continental ice sheets, sea level was over 300 feet lower. Meaning that at least 100 feet of the seamount would have risen above the water, to form an island many miles longIt was almost directly west of the Straits of Gibraltar – exactly where Plato had described the city of Atlantis, before it sank beneath the waves.Could it be? These scientists began to wonder, had they accidentally discovered the lost city?They sent down the ship’s ROVs – Remote Operated Vehicles, to explore the surface of the seamount. They found sediments and other evidence of erosion, only possible if the island were indeed above water.But unfortunately, no ruins of an ancient city, or any evidence of human habitation.Their continued research did provide valuable data about the volcanic past of the eastern Atlantic, the geologic formation of seamounts, and how they impact ocean currents – their original mission.But Atlantis remains elusive, perhaps waiting for future scientists.
Transcribe →Flash Floods
Jun 2600:02:00Tap to summarizeThere are many kinds of floods.River floods develop slowly, water gradually rising over days, providing ample time to evacuate.Coastal floods come mostly from storm surges, when a hurricane or tsunami makes landfall. Coastal communities also have evacuation warnings. But when not, these can be catastrophic.Urban flooding happens increasingly as paved areas expand, preventing the land from absorbing rainfall.Flash floods, though often localized, can be the deadliest for their size, simply because they are sudden. They occur when torrential rain falls, snow rapidly melts, or water is forced down a river.They can send a wall of water tens of feet high hurtling down a channel, faster than people can seek safety. They can sweep away vehicles and roads, making escape impossible. They can carry debris and chemicals, leaving long-lasting devastation in their path.Despite a few fatal incidents, authorities are improving their ability to predict and react.AI analysis of massive weather data now provides longer lead times for flash floods, especially in the Southwest U.S., Latin America, and Asia.Meanwhile, smarter urban planning and development include runoff zones to capture floodwaters, and innovative warning systems that alert and prepare the populace.In the rare case you receive an alert, move quickly to high ground and stay safe.
Transcribe →Listening to Soil
Jun 2600:02:00Tap to summarizeJust eight percent of Earth’s surface is covered in topsoil -- but that grows 95 percent of our crops.And healthy plant growth depends on healthy soil. Which depends on a healthy population of soil life.As noted in an earlier EarthDate, a single handful of healthy soil contains more microbes than the human population of Earth. And more biodiversity than the entire Amazon. One handful.Along with microbes, there are fungi, worms, insects, plant roots, and much more. And they all make noise.Sixty years ago, ecologists began recording the sounds of nature, to understand what species populate different areas – cataloging, for example, the bird, insect, and animal noises of a forest.But when one curious scientist poked a microphone into the ground, he was blown away. Turns out soil life makes noises of its own. From grubs chewing on roots, to worms slithering through tunnels, to millipedes’ feet drumming.In fact, they realized you can tell a lot about soil health simply by listening to it. Conversely, degraded soils have less active life, and therefore less sound.Ecologists now monitor soils with a microphone, helping evaluate their resident lifeforms, crop productivity, and the success of soil replenishment programs.Their discoveries remind us that soil is a vital, living system, worth protecting for its own sake – and ours.
Transcribe →Slowing Down to Breath
Jun 2500:02:00Tap to summarizeBillions of years ago, the globe spun twice as fast as today; a complete rotation took just 6 hours. Then Earth’s rotation slowed, and that’s why you’re here listening to this episode. Let me explain.The atmosphere of early Earth was made up of methane, CO2 and sulfur gases. But no oxygen.Eventually, as noted on a prior EarthDate, cyanobacteria, blue-green algae, began to produce oxygen through photosynthesis.At first, the amount of oxygen they released was so small that it was absorbed by iron in seawater, and no oxygen entered the atmosphere.Scientists researching this phenomenon found a similar low-oxygen, high-sulfur environment in sinkholes at the bottom of Lake Michigan, where modern blue-green algae grows.There, and in a lab mimicking that environment, they tested the effects of day duration on oxygen production.Turns out blue-green algae is dormant in the morning. In a short day, it was nearly dark again by the time it started producing oxygen. And that small amount was reabsorbed by the algae before it could enter the water.As days lengthened, the algae had enough time to produce enough oxygen to escape.Over millions of years, oxygenated water first gave rise to aerobic sea life. Then an oxygen-rich atmosphere allowed land creatures to develop and thrive, which eventually led to…you, and me, and a radio show called EarthDate.
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