Carbon dioxide is more than an industrial pollutant driving climate change. The gas also played a pivotal part in the dramatic story of the beginning of all life. Starting in the ocean depths, dissolved CO2 commingled in a turbulent mix of chemicals heated by hydrothermal vents may have kickstarted carbon-based life. As the planet’s thermostat, carbon dioxide has taken the Earth on wild temperature swings, from sweltering toxic hothouses that drove mass extinctions to the frigid Snowball Earth from which early life barely escaped. With life’s growing complexity, CO2’s role evolved.
Episodes
Telescopes are like light buckets. The bigger the telescope, the more light collected for astronomers to observe. With recent advances in technology, amateur astronomers can join professionals for a chance to observe stellar nurseries and exoplanets many light-years away. But as our capabilities increase, so do the mysteries, including those around high-energy bursts coming from an otherwise unremarkable part of the universe. Understanding fast radio bursts could turn physics on its head.
We admire the ornamental beauty of flowers in a garden, but those blooms are more than lush color. The seemingly fragile, delicate petals are part of a resilient, adaptive innovation that arrived on the scene 250 million years ago and transformed life on the planet. Much life, including us, would not have evolved without flowering planets. Yet the power of the petal is often overlooked. How does our perspective on nature’s web change if we give flowers the credit they deserve?
Breakthroughs around the detection of cosmic neutrinos — the “ghost” particles that may reveal why matter, not antimatter, fills the universe — recently earned a physicist the Nobel Prize in Physics. But one group of neutrino hunters isn’t waiting for supernovae to churn up these high-energy particles. A massive new experiment that spans three states will create neutrinos and fire them into liquid argon to better understand their mysterious behavior.
A growing online movement of sunscreen skeptics believes that sunblock is toxic, even suggesting that it might cause skin cancer. Medical experts, concerned by rising skin cancer rates, are rushing to push back against these claims. Meanwhile, new research suggests that too little sunlight could be detrimental to health and links it to some cardiovascular disease and cancer. How do we navigate through the darkness of these seemingly conflicting messages about sunlight?
Healthy rivers and riparian ecosystems are teaming with life, but should rivers themselves be considered alive? The question is central to the growing rights-of-nature movement that claims that ecosystems and entities, like rivers, have legal rights. After Ecuador enshrined the rights of nature in its constitution, lawyers employed the new personhood status to stop mining companies from clearing a section of the Los Cedros River and its surrounding biodiverse cloud forest. Granting rivers moral standing comes as over-damming, pollution, and climate change have put them in crisis globally.
Extreme heat is taking its toll on the natural world. We use words like “heat domes” and “freakish” to describe our everyday existence. These high temperatures aren’t only uncomfortable - they are lethal to humans, animals, and crops. In search of an answer to our episode’s question, we discuss the dilemma of an ever-hotter world with an author who has covered climate change for more than two decades.
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A new space telescope will soon give us an expanded field of view of some of the strangest phenomena in the cosmos. The launch of NASA’s Nancy Grace Roman Space Telescope will initiate this instrument’s contributions to the understanding of black holes, dark matter, and dark energy. It will also further the search for exoplanets. The project’s principal and deputy investigators join us to describe the telescope’s science goals, and astrophysicist Neil DeGrasse Tyson provides his big picture view of the most exciting recent discoveries in astronomy and cosmology.
The abrupt defunding of USAID in 2025 caused global shockwaves. The cuts thrust recipient countries who were dependent on foreign aid for medical care into health crises. One area that has been particularly hard hit is Malawi, a country in southeastern Africa where doctors and community organizers are struggling to fill the gaps in essential services left in the wake of the USAID cuts. The loss of local outreach clinics and lack of fuel for ambulances has caused severe delays—and sometimes tragic outcomes—in providing care to mothers and children.
They are known for holding branches in their paws and gnawing on them like corn cobs. They build lodges and dams which occasionally flood roads. Cute, comical, and considered pests, beavers were nearly hunted to extinction for their pelts before conservation efforts allowed their populations to rebound. Now environmentalists and engineers are reintroducing North America’s largest rodent to drought-prone habitats across the country.
Whether in miles or pounds, meters or kilograms, we take daily measure out our lives. But how did these units ever come to be, and why do we want to change them? From light-years to leap seconds, we look at the history of efforts to quantify our lives and why there’s always room for greater precision. Plus, we debate the virtues of staying imperial measurements vs. going metric.
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Are we alone in the universe? Is there other intelligence out there? COSMIC, the most ambitious SETI search yet, hopes to answer that. We hear updates on this novel signal detection project being conducted on the Very Large Array in the desert of New Mexico.
What physical activity gives you joy? Whether it’s walking, running, dancing or swimming, your body evolved to do it. We are made for movement. But there’s a cost, as anyone with a sore neck or aching back knows. From the tiny muscles in our skin, which raise the hair on our arms, to the intricate mix of bone, blood vessels, and nerves in our neck, natural selection has struck a delicate and sometimes wacky balance between utility and form.
Electricity plays an important role in our everyday lives, including allowing our bodies to communicate internally. But some research claims electricity may be used to diagnose and treat disease? Could electric pulses one day replace medications?
We speak with experts about the growing field of bioelectric medicine and the evidence for electricity’s healing abilities. Their comments may shock you.
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Earthworms may be small, limbless, and blind but, as Darwin observed nearly 150 years ago, they play a critical role in soil ecology. Darwin’s 19th century insights about the slimy invertebrates are far-reaching, serving as the backbone of modern ecology as a whole. In recent years, scientists are putting their ears to the ground, listening to worms to monitor soil health. Meanwhile, laboratory studies on another kind of worms—flatworms—are providing insights about how memories are stored, and how stem cells self-renew.
The Arctic serves as the world’s refrigerator, keeping the planet cool. But temperatures in the Arctic are rising nearly four times faster than the rest of the world and its sea ice is near a historic low. We put out a call to scientists aboard research vessels currently sailing in the Arctic Ocean, and two answered “aye.” Hear our ship-to-shore conversations with them about how warmer temperatures affect life on land and sea. Plus, a biologist who recently returned from the field describes how he inadvertently stumbled upon surprising data during his decades-long study of polar bears.
Another scorching summer has us blasting the AC and grabbing a chilled drink. Air conditioning and refrigeration may beat the heat, but they also present a dilemma. The more we use them, the more greenhouse gases we emit, the hotter the planet becomes, and the more we require artificial cooling. Can we escape this feedback loop? We look at the origins of these chilling technologies, tour the extensive chain of cold that keeps food from perishing, and consider how a desert city like Phoenix could not exist without AC.
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The powerful gene editing tool CRISPR is already being tested on animal and plant cells. It has even been used on humans. How might this revolutionary tool change our lives? On the one hand, it could cure inherited diseases and rid the world of malaria-spreading mosquitoes. On the other hand, scientists using it are accelerating evolution and introducing novel genetic combinations that could transform our biological landscape in unforeseen ways. We explore the ramifications of this revolutionary technology.
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Many of us know the feeling: we intend to go to bed but pull out our phones for one last scroll. Setting them aside hours later, we’re wide awake, unable to fall asleep. For years, scientists have singled out blue light emitted from our devices as the key culprit behind our post-scrolling insomnia, but the scientific consensus is shifting. Although blue light signals to brains that its daytime, surprising new research suggests that our glowing screens may play a smaller role than previously thought.
Long before Yuri Gagarin became the first human to go into space, Laika, a stray dog, crossed the final frontier. Find out what other surprising species were drafted into the astronaut corps.
They may be our best friends, but we still balk at giving other creatures moral standing. And why are humans so reluctant to accept the fact that we too are animals?
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