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No, it has nothing to do with volcanic activity.
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One by one, Tyson sets up the objections touted by those who deny the reality of climate change, and knocks them down with scientific facts.
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Aside from seasonal fluctuations, until the 19th century, CO 2 levels hadn’t fluctuated by more than 1% over millions of years. ( It’s now known as the “Keeling Curve.”) We can see this in ice core samples taken in Antarctica and Greenland, giving us a detailed “diary” of Earth’s atmospheric history. And he made another startling discovery: an alarming sharp rise in the overall levels since the Industrial Age, when humans started burning coal, oil and gas for energy. (The seasons are reversed in the Southern Hemisphere.) So there’s a natural fluctuation to CO 2 levels in the atmosphere.Īn oceanographer named Charles David Keeling was the first to notice this when he measured how much CO 2 was in the atmosphere. We don’t think of planets as living organisms, but Tyson insists that the Earth “breathes” with the seasons, taking in CO 2 (via trees and other vegetation) in the spring and “exhaling” it back into the atmosphere in the winter. We’re in the “Goldilocks zone” when it comes to CO 2 levels, but it only takes a tiny shift in the balance to tip us into a runaway greenhouse effect - and that is precisely where we are heading. If there were none, Earth would be a ball of ice too much, and Earth would look like Venus. So there were only trace amounts of CO 2 in our atmosphere: less than three molecules in 10,000. Whereas most of the Venusian CO 2 is in gaseous form in the atmosphere, our planet developed an efficient conversion cycle through which carbon could be stored in coral reefs, or limestone rock, - like the stunning White Cliffs of Dover on the coast of England. But the same fundamental science applies to Earth.Įarth benefited from a milder version of the greenhouse effect. “Nature can destroy an environment without any help from intelligent of life,” says Tyson. True, the catastrophic climate change on Venus had nothing to do with mankind. We can learn much from Venus about the possible fate of our own pretty blue planet. It’s called the runaway greenhouse effect. So that energy never escaped and Venus got hotter and hotter. So why isn’t Venus a block of ice? A little light gets through - but it can’t back out again because there is so much carbon dioxide in the atmosphere. As host Neil deGrasse Tyson points out, Venus is covered by thick sulfuric clouds, which keep much of the sun’s light from ever reaching the planet. What happened to Venus to turn it from a nascent paradise into an uninhabitable hell? That fiery temperature isn’t because the planet is 30% closer to the sun. Thanks to on-board cooling systems, the craft stayed operational for a couple of hours - long enough to take pictures of the planet’s surface and beam them back to Earth, before the searing heat fried the electronics. Visit Venus today, however, and you’ll find that its once abundant oceans have long since evaporated away because of the broiling temperatures - hot enough to melt lead, and certainly hot enough to destroy Venera 13, a Soviet space probe that landed on the surface of Venus in 1982. Venus was not much different from Earth back in the earliest days of the solar system, with vast oceans and an atmosphere potentially friendly to life. Is it getting hot in here? In what is likely to prove one of its most controversial episodes yet, this week’s “Cosmos” lays out the powerful scientific case for climate change, framed within a tale of two planets: Venus and Earth.