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.
123episodes
Episodes
Newest firstAll episodes
Mining, Past and Present
3w ago00:02:00Tap to summarizeToday we make stuff in three ways. Plants and animals make our food, wood and fiber. Oil and gas make plastic, fuels, chemicals and clothing. And rocks, dug out of a mine, become metal, concrete and stone – which make our buildings and roads, planes, trains and automobiles, energy infrastructure and much more. By weight and value, our most important mined product is coal – which makes about 1/3 of global electricity. Coal was also the first thing humans mined at scale, 20,000 years ago in South Africa. Around 6,000 years ago, we figured out how to smelt metal out of ore. Copper, gold, silver, tin and iron shaped civilizations in the Bronze and Iron ages, making weapons and tools, art and currency. Today, we mine in several ways. Surface mines dig out shallow ore deposits or stone. Underground mines dig tunnels to reach deeper reserves. Placer mining separates minerals from erosion runoff. Solution mining dissolves minerals in place with a solvent, which is then pumped to the surface and purified. All forms of mining have environmental impacts. Surface mines can deforest large areas and disrupt ecosystems. Waste rock, and polluted water and air can impact local communities. In another EarthDate, we talk about ways to address these impacts, as we ramp up mining to meet the demands of new technology.
Transcribe →Urban Mining
3w ago00:02:00Tap to summarizeOn another episode, we talk about how mines have a large environmental footprint. Think of a giant pit, with huge machines digging out ore. By contrast, think of your old smart phone. In one ton of discarded phones there’s 80 times more gold than in one ton of ore. Electronic waste, like phones and computers, contains gold, silver, palladium and rare earth elements. Old batteries contain lithium, cadmium and other heavy metals. Construction and demolition debris contains copper from piping and air conditioning, and steel from rebar and beams. Old cars and trucks contain steel, aluminum and other metals. This can make cities a repository of metals more concentrated than any mine. And makes this waste the resource for a new industry called ‘urban mining.’ The challenge is gathering that varied waste from across the urban environment, then sorting and disassembling it to be processed. That takes energy, time, labor and money. But new recycling programs, often powered by AI, sort materials with magnets and robots, then use mechanical shredders and chemical solvents to break them down into simpler components. Producing metals this way uses less energy and water than mining and processing new ore, with potentially less environmental impact – while also reducing the need for new metals, sometimes imported from unfriendly countries. In the future, more metal will come from these sources much closer to home.
Transcribe →Mining, The Future
3w ago00:02:00Tap to summarizeIn another EarthDate, we talk about how mining provides the materials to build the modern world. But new technology is changing that world. We’re building huge new data centers for AI; batteries to power EVs, and stabilize the power grid; and enormous volumes of solar panels and wind turbines. All these will require a lot more mining. And all mining impacts the environment. So engineers are working to make the process cleaner and safer. Mine tailings – the waste rock – are today kept in huge ponds, which can spill catastrophically. New techniques dry them out for safer storage, or to use as construction materials, and recycle the water. And more mines are capturing, treating and reusing water throughout their processes. Many mines are working to reduce emissions at the site, switching diesel equipment and trucks for electric motors, requiring more electricity.More advanced automation makes mines more efficient. More advanced exploration uses less energy and disturbs less land to find new resources. New technologies extract lithium directly from hot, deep brines. And use electricity, instead of high heat or strong acids, to separate metals from mining waste. Meanwhile, improved recycling programs recover more copper, lithium and other metals from old electronics, batteries and scrap, to help reduce the need for new mines. And we talk about that, on another EarthDate.
Transcribe →Light Speed Under the Sea
3w ago00:02:00Tap to summarizeIn 1858, Queen Victoria sent a telegraph to U.S. President Buchanan, via the first undersea cable. The cable worked for just a few weeks, but it launched an international cable network that still dominates global communication. We think we live in a wireless world. But it’s just the short hop from our phones and wifi to a receiving antenna. Nearly everything after that is transmitted by cable, on land and undersea. Undersea cables made of copper served the world for more than a hundred years. Then, in 1988, the first fiber-optic cable was laid. They’re made of strands of ultrapure glass, no thicker than a human hair. Hundreds of strands are bundled together and protected by braided metal and nylon, jacketed in plastic. At one end, electrical signals are converted to light by a laser, then shot down the fiber-optic cable, sometimes more than a thousand miles, between countries and continents. In the shallows, they’re buried in trenches to protect them. In deep water, they’re simply laid on the seabed, which is less expensive, but exposes them to harm. There are now thousands of subsea fiber-optic cables, stretching almost 1 million total miles, transmitting 95% of international internet and voice traffic. And more cables are being laid each year. So next time you make an international call, pause for a moment to imagine your voice rocketing along at the speed of light, under the sea.
Transcribe →Lakes of Life
3w ago00:02:00Tap 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
3w ago00:02:00Tap 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 →We Changed Horses
3w ago00:02:00Tap 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 →Chernobyl: Rebirth
3w ago00:02:00Tap 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 →The Moth with Two Maps
3w ago00:02:00Tap 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
3w ago00:02:00Tap 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 →