Episodes

  • Recycling Carbon

    Recycling Carbon
    Feb 23 2026
    All known life on Earth is carbon based. Today, though, when we hear about carbon, it’s usually in terms of emissions. Or the idea of capturing and storing those emissions. What you may not have heard is that Earth has been emitting and storing carbon for millions of years, cycling it between sky, sea, soil, and rock. Deep in the geologic past, atmospheric carbon dioxide was 10 times higher than today. Then ancient ocean life began to use it. Early marine organisms used CO2 dissolved in seawater for photosynthesis, forming the base of the food chain. Other organisms used it to build their exoskeletons and shells. When they died, their carbon-rich remains sank to the seafloor and were buried. Very slowly, carbon was being stored within the earth. Millions of years later, plants evolved and dramatically changed the carbon balance. They began to turn huge volumes of atmospheric carbon into organic carbon like carbohydrates and cellulose. Some organic carbon goes back into the atmosphere or the soil. Some gets buried and becomes part of sedimentary layers and, with enough pressure and time, can be cooked into hydrocarbons—fossil fuels. Today, the burning of fossil fuels is moving ancient carbon stored in the earth back into the atmosphere. Researchers are studying different ways to sequester that CO2, and we’ll talk about that on a future EarthDate.
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    2 mins
  • Life on Ice

    Life on Ice
    Feb 23 2026
    The ice sheets that cover Antarctica and Greenland were once thought to be sterile, inhospitable places. But recently, scientists have discovered they hold vast populations of life. There were times in Earth’s history when there was no polar ice at all. And many times, like today, when ice sheets formed at the poles. In the Antarctic today, ice sheets cover 5 million square miles with over a mile of ice that’s up to 1 million years old. In subglacial polar lakes, this life may not have seen the light of day for 20 million years. This enormous quantity of ice has been shown to harbor microbes in huge numbers. Scientists estimate their total organic carbon biomass would be about ten times that of all humans on Earth. And, perhaps not so surprisingly, with ice this old, the bacteria are ancient, too. Viable species hundreds of thousands of years old have been discovered in ice, frozen there all that time in a sort of suspended animation. But once liberated and revived in labs, some started to replicate as normal. With them are previously unknown viruses, and certainly new microbes that are yet to be discovered. And this has scientists both concerned and excited. With continued polar ice melt, some of these microbes could bring ancient diseases…while some could bring new cures for existing ones. Of course, this has prompted research; and we’ll look into that in a future EarthDate.
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    2 mins
  • Global Smartphones

    Global Smartphones
    Feb 23 2026
    Remember the periodic table from high school? Neither do I! But about three-quarters of the elements are inside your smartphone, from minerals mined all over the world. The glass on the front is a special hardened type. It’s made of quartz, which may have come from the USA, and aluminum, which probably came from Australia. It’s then treated with potassium salts, likely from Canada. For scratch resistance, it’s given a coating, made of iridium from South Korea and tin from Indonesia. The colors on its screen come from rare earth elements, mostly from China. Its microelectronics could include copper from Chile, silver from Mexico, platinum from South Africa, and tungsten from Russia. Its tiny capacitors use tantalum from central Africa or Brazil. Your phone’s rechargeable battery is made of lithium, which may have come from Argentina; cobalt from the Congo or Zambia; and pure graphite from India. Petroleum, from many sources around the world, is used to ship all these minerals to factories, where they’re assembled into parts, then shipped again to be assembled into phones. If supplies of any of these elements, from any of these countries, were to be restricted, it could disrupt the price and availability of the phones that billions of us rely on. There are also serious environmental impacts to mining these minerals. Recycling the billions of old phones will ensure we have materials available for new ones.
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    2 mins
  • The Great Smog

    The Great Smog
    Feb 23 2026
    You’ve heard of the London fog, but how about the “London Smog”? Well, it killed at least 8,000 people and sent another 150,000 to the hospital. How was this? In the years after World War II, England had rebuilt its factories and power stations, and all were burning coal. London residents, too, were burning coal in their homes to keep warm. But England had sold its premium coal to pay war debts and was using a poor grade with high sulfur content. On a particularly cold winter day in 1952, with furnaces and fireplaces working overtime, a fog rolled in. Fog is just a cloud on the ground. It forms when humid air cools and its water vapor condenses. This time, there was also a high pressure area that sat over London. Together they trapped the coal emissions, and the fog became the “Great Smog.” Sulfur dioxide in the smoke mixed with water vapor in the fog to form a dilute sulfuric acid. As the water evaporated, the fog became ever-more acidic and stank of rotten eggs. Breathing it damaged lungs and led to serious lung infections. Hospitals overfilled. People began dying in such numbers that undertakers ran out of coffins. Finally, 5 days after it began, wind blew the toxic fog out to sea. Today, scientists are using lessons from the Great Smog to mitigate the effects of smog in China and other industrializing areas that depend on coal for electricity.
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    2 mins
  • Our Unmapped Ocean

    Our Unmapped Ocean
    Feb 23 2026
    If you took a flight from New York to Beijing, for 1,400 miles of it, you’d be flying over mostly unmapped ocean. We don’t know exactly how deep it is. We don’t know the shape of the ocean floor. It’s a mystery. In fact, we don’t understand the vast majority of the seafloor. Our maps of the moon, Mars, and even Venus are 50 times more detailed. Near the coasts and continental shelves, where waters are shallow and boat traffic is high, we’ve used sonar from ships to build high-resolution seafloor maps. But these cover just 10% of the ocean. The rest, with an average depth of 2.5 miles, is too deep for ordinary sonar, and too remote and dark for other types of visual mapping. So we’ve resorted to measuring the ocean surface with satellites, then interpreting the seafloor from that. The best resolution we’ve been able to manage is a data point every 3 miles. Exactly what’s happening between these points? We have little idea. And this is a bit of a problem. The contours of the seafloor shape the paths of tsunamis and the direction of major currents that shape our weather. When a cargo ship or a jetliner goes missing, we struggle to locate them. Who knows what we might discover with a better knowledge of the deep ocean. New minerals and resources. New life forms. Things so new we can’t even imagine them.
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    2 mins
  • Under Pressure — Geysers

    Under Pressure — Geysers
    Feb 23 2026
    For centuries, geysers have captured our imagination, in places like Yellowstone National Park, where 4 million visitors flock each year. This is partly because geysers are spectacular, and partly because they’re rare. There are only about 1,000 worldwide, and nearly half of them are in Yellowstone. Most others occur in just five countries. Why are there so few? They require very specialized geology. At the surface, they need caprock, to trap water. In the subsurface, they need fissures in the rock, so water can flow into and collect in reservoirs and cavities. Below that, they need intense heat—all geysers are in volcanic areas. The bottom of the geyser’s water column is closest to the heat, under higher pressure—which raises the boiling point. So the water keeps heating without converting to steam. The heat travels up the water column, eventually reaching the top. There, the pressure is lower, so the water can boil. As it turns to steam, it releases pressure on the water just below it. Which can now boil, releasing pressure on the water further down, and so on. This chain reaction produces huge volumes of steam, which erupt out the top of the geyser. In large geysers, steam can carry thousands of gallons of boiling water into the air, in fountains that can last a few seconds to a few hours and reach heights up to 300 ft. If you go to see one, prepare to be amazed. It’s one of nature’s greatest shows.
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    2 mins
  • Dinosaurs in Your Backyard

    Dinosaurs in Your Backyard
    Feb 23 2026
    There’s a good chance that a dinosaur once stomped through your backyard. It’s more likely, though, that there’s one there today. I’m talking, of course, about birds. How exactly is T. rex related to the common house sparrow? Around 230 million years ago, there was a group of dinosaurs called the theropods, which included the bipedal carnivores. With their back legs used for movement, their front legs were free to specialize. In T. rex, they became, well, not much. But in other species they became grasping claws. While T-rex and his cousins were getting bigger, the grasping-claw dinosaurs got smaller. One of these subgroups, the coelurosaurs, evolved two important things: They became omnivores, so they could survive on a broader diet. And they grew early feathers, perhaps to keep warm. Suggesting they may have also become warm-blooded, like birds. With these traits in place, this group evolved rapidly. They got smaller still and developed early wings, for hopping and then gliding. This was a huge advantage, which encouraged ever-more-capable flight. Over millions more years, they evolved sophisticated feathers and hollow bones. Finally, to navigate in three dimensions and across huge areas, they developed greater brainpower and better communication systems. When that asteroid hit Earth 66 millions years ago, it ended the reign of T. rex. But birds, with their new capabilities, flew on. So look for a little dinosaur on your windowsill.
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    2 mins
  • Digging Soil

    Digging Soil
    Feb 23 2026
    Here’s my vote for most underappreciated Earth system: dirt. All terrestrial life depends on it, but almost no one gives it any love. The soil is a place where air, water, rock, and life intersect. It’s the surface we live on, farm in, build upon, and are often buried in when we die. For dirt to be good soil, it needs some special ingredients: decomposed bedrock—which gives soil its minerals; organics—from dead plant and animal matter; and life—lots of it. In a single shovelful of dirt there are trillions of creatures, from earthworms to bacteria, and thousands of feet of fungus. Soil’s most important job is to provide plants their nutrients and a place to anchor their roots. But it does many other amazing things. It absorbs, stores, and releases most of the water on Earth’s surface and filters it before it moves to an aquifer. By managing water, soil limits surface runoff and flooding. Soil stores and recycles minerals and other nutrients, so that living things can use them again and again. It absorbs and emits gases like carbon dioxide, methane, and water vapor, constantly interacting with the atmosphere. It even provides building materials, like sand for concrete, clay for bricks, and lumber from trees growing on healthy soil. How we choose to take care of our dirt—how we farm it, keep it free from pollutants, and recognize that it’s a living ecosystem—impacts the health of all other life on Earth.
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    2 mins