Cosmos: A Spacetime Odyssey Recap - Episode 112

"The World Set Free"

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Cosmos: A Spacetime Odyssey Episode 12. FOX

 (Note: This is a recap of episode 12 of the first season of Cosmos: A Spacetime Odyssey entitled "The World Set Free" and hosted by Neil deGrasse Tyson. If you are looking for a different episode's recap, click here.)

This week’s episode of Cosmos starts off with our fearless host Neil deGrasse Tyson telling us once there was a world not so very different from our own. There were sometimes natural catastrophes like volcanic eruptions and asteroids.

However, for its first billion years, it was a paradise. This is Venus until things started to go wrong. The music swells as we see smoking volcanoes everywhere. Cue the intro music and credits.

When we get back, the music is still swelling and the landscape of the ideal Venus changes rapidly. Tyson tells us nature is a delicate balance and once Venus started to go wrong, there was no turning back.

The Greenhouse Effect on Venus

The Ship of the Imagination takes us to the surface of Venus today. The oceans are long gone and the surface is hot enough to melt lead. It isn’t because Venus is closer to the Sun. It’s because it is covered by clouds of sulfuric acid that block the Sun. It should be cold, but the little bit of Sun that can reach the surface can’t get back out. Thick clouds of carbon dioxide cover the planet and trap the heat in.

Tyson points out that no one is driving gas guzzlers on Venus, and that nature can destroy itself without any help from intelligent life.

Venus is in the grips of a devastating greenhouse effect.

Why does it look like we’re inside a bowl? There is extreme pressure from the atmosphere. In 1982, the Soviet Union managed to land the probe on Venus called the Venera 13. They kept it cool enough for 2 hours in order to photograph its surroundings and transmit them back to Earth before it was fried.

Venus and Earth started out with about the same amount of carbon, but they took different paths. On Venus, it is almost exclusively in the form of gas in the atmosphere. On Earth, most of the carbon is stored in rock, like the White Cliffs of Dover. We see beautiful pictures of the cliffs and then Tyson tells us one celled algae created these cliffs. Trillions of these organisms that are smaller than a pinhead harvested the carbon dioxide that volcanoes spewed into the oceans over millions of years. They then turned it into thick deposits of limestone on the ocean floor. Later, the Earth pushed up seafloor and carved out the cliffs. Other marine creatures took in carbon dioxide to build coral reefs. As a result, only a trace amount was left in the atmosphere. Fewer than 3 molecules per 10,000 in the atmosphere were carbon dioxide. This made the difference between what Venus is like now and how habitable Earth is in comparison.

The Greenhouse Effect on Earth

With no carbon dioxide at all, Earth would be frozen. If we had twice as much, only 6 molecules per 10,000, it would be too uncomfortable for life. It wouldn’t even be close to as hot as Venus, though. Venus lost its ocean to space billions of years ago.

Without an ocean, there was no way to store carbon dioxide as a mineral. The gases from the volcanoes just continued to build up. Today, the atmosphere is 90 times heavier on Venus than Earth’s atmosphere. Almost all of it is due to carbon dioxide.

On Earth, there is a lot of life that can use the carbon dioxide. Most of the carbon dioxide is used by forests. Almost all forests on Earth are in the Northern Hemisphere. When it is spring time in the north, these forests can use the carbon dioxide and grow. The amount of carbon dioxide in the atmosphere goes down.

When the trees lose their leaves in the fall, they decay and recycle the carbon back into the ground and the atmosphere and the carbon dioxide levels increase. The same thing happens in the Southern Hemisphere in the opposite times of year.

However, most of the Southern Hemisphere is made up of oceans, so the forests in the north control the levels of carbon dioxide.

This has been going on for tens of millions of years. No one noticed this until 1958 when an oceanographer named Charles David Keeling devised a way to accurately measure the carbon dioxide levels in the air. He discovered a rapid rise, unprecedented in human history, of carbon dioxide. This has continued to rise ever since.

On the screen, a graph of this data appears as Tyson’s tone gets serious. It is much higher than times when agriculture was on the rise. In fact, the Earth has seen nothing like it in 3 million years. How could we be so sure? The evidence, Tyson tells us, is written in water.

Ice Core Data

After a commercial, we return to the Ship of the Imagination floating over the Earth. Tyson says the Earth keeps a detailed diary written in the snow. Climate scientists have drilled ice cores from the glaciers in Greenland and Antartica. This ice has the gases of those ancient times trapped in them. We can read the unbroken diary of the Earth’s atmosphere for the past 800,000 years. In all that time, the amount of carbon dioxide in the air never rose to over .03 of 1%. That is, until the turn of the 20th century. It has been going up steadily and rapidly ever since.

The Industrial Revolution has seen a significant rise of greenhouse gases spewed into the atmosphere at rates faster than life can absorb it. This means the gases are building up in the atmosphere.

Are Humans Causing Global Warming?

The planet is heating up. Every warm object radiates thermal infrared light that we can’t see with the naked eye. We glow with visible heat radiation. Tyson shows us what Earth looks like with an infrared camera. The carbon dioxide traps the heat the Earth is radiating and sends it back to the surface, warming it up even more. That is all there is to the greenhouse effect. There is nothing controversial about it. If we didn’t have any carbon dioxide in the atmosphere, the Earth would be one great big snowball and we wouldn’t be here.

So a little bit of greenhouse gases are necessary, but a lot can destabilize the climate and wreck our life.

Next, Tyson takes on one of the most popular climate change denier arguments. How do we know that humans are causing it? He gives many reasons of what could be causing it besides humans. Maybe the Earth itself is causing it and maybe it has nothing to do with the coal and oil we burn. Maybe it’s those “damn volcanoes”, as Tyson puts it. He tells us that every few years Mt. Etna in Sicily blows its stack. Each big eruption sends millions of tons of carbon dioxide into the atmosphere.

If we combine this with every large eruption on the planet, the largest scientific estimate would be 500 million tons of volcanic carbon dioxide entering the atmosphere every year. Sounds like a lot, doesn’t it? That isn’t even 2% of what our civilization cranks out every year. The measured increase of carbon dioxide in the atmosphere correlates to the amount of greenhouse gases we are pumping into the air every year.

Differences in Carbon Dioxide

Tyson is back at the White Cliffs of Dover as he tells us that volcanic carbon dioxide has a distinct signature. It is slightly heavier than the kind we produce by burning fossil fuels. Scientists can tell the difference between the two when they are studied at an atomic level. It has been concluded the extra carbon dioxide in the air is not the kind volcanoes make. This, coupled with the correlation between amount of fossil fuels burnt and the increase in the atmosphere, makes a pretty tight case for human caused global climate change.

How much is 30 billion tons of carbon dioxide per year? If you could compress it to solid form, it would take up the same amount of room as the White Cliffs of Dover. We are putting this much into the atmosphere every year relentlessly. Unluckily for us, our major waste product just happens to be the regulator of the global climate. It is too bad carbon dioxide is a colorless gas. Maybe if our eyes were sensitive to carbon dioxide, we could overcome the denial our impact has on the atmosphere.

Evidence for Global Warming

Back on the Ship of the Imagination, Tyson tells us the evidence that the Earth is getting hotter is all around us. First, just check the thermometers. People around the world have been gathering reliable temperature data since the 1880s. NASA has made a map tracking the temperatures around the world through time. We see the map as Tyson explains that the yellow color is warmer than the 1880s, orange is hot, and red is even hotter. Back in the 19th century, a forgotten genius at the greatest fair the world has ever seen demonstrated the solution to this problem.

Back from the commercial, Tyson tells us once there was a world not too cold or not too hot. It was just right. Then, there came a time when the life it sustained noticed the planet was changing. We see glaciers melting and massive amounts of rains and floods. It wasn’t like we didn’t see it coming. As far back as 1896, Svante Arrhenius calculated that doubling the amount of carbon dioxide in the atmosphere would melt the Arctic ice. In the 1930s, Physicist E.O. Hulbert at the Naval Research Laboratory confirmed that result. The English Engineer Guy Callendar combined all the evidence to show that the global carbon dioxide and the global temperature were increasing. We see an old video clip from 1958 discussing how global temperatures were already going up and what caused it.

In 1960, Carl Sagan’s doctoral thesis included calculations of the greenhouse gases on Venus. He had studied the atmospheres of all the planets, including our own. In the original Cosmos series in 1980, we see a clip of Sagan warning the viewers that we are releasing vast quantities of carbon dioxide, causing the greenhouse effect and it would not take much to destabilize Earth’s climate and turn this heaven into a kind of hell.

Since he spoke those words, we’ve spewed out another 400 billion tons of carbon dioxide. If we don’t change our ways, what will our children’s future be like? If we do not change our ways and continue with business as usual, they will be in for a rough ride. They will see killer heat waves, massive droughts, rising sea levels, mass extinctions of species. We inherited a mostly stable environment where our ancestors thrived for thousands of years. Now our carelessness and greed put all of that at risk.

Weather vs. Climate

Tyson, walking along a shore with crashing waves, tackles another argument often spouted by the climate change deniers. If scientists are so good at making dire predictions about the future, why can’t they accurately predict the weather? This year, we also had a colder winter than usual so doesn’t that mean we had a winter of global cooling instead of global warming? Here is the difference between weather and climate. Weather is what the atmosphere does in the short term. Even a microscopic change can cause a big difference in the weather. That is why the 10 day weather forecast is useless.

Climate is the long term effects of weather averaged together over long periods of time. It is how the energy balance is changed by forces of the Earth. It is impacted by the tilt of the Earth on its axis, the amount of Sun absorbed and reflected, and the concentration of greenhouse gases in the air. A change in any of them makes changes to the climate that are predictable.

While he is explaining this, Tyson is walking a dog down the beach.

He makes an analogy to prove his point. The way the dog is meandering down the beach is unpredictable and cause a short term change like the weather. It is almost impossible to predict what will grab his attention next. However, we know the range of his meandering because he’s on a leash. We can’t see the climate directly, but we can see an average of the weather to show a trend over long periods of time. Tyson says his straight path down the beach shows is like that trend. That is climate.

Weather is hard to predict, but climate is predictable. It has changed many times throughout the Earth’s history but only because of the Earth’s force. The force of the climate change right now is due to the increased carbon dioxide in the atmosphere. That trapped heat has to go somewhere, and it is mostly getting absorbed into the oceans. This is most apparent in the Arctic glaciers.

Melting Ice Caps

Tyson again jumps right into another climate denier argument.

So what if we are losing ice near the North Pole? No one lives there so why should anyone care? Tyson tells us ice is the brightest natural surface on Earth and the deep depths of ocean water is the darkest. Ice reflects a large amount of sunlight back into the atmosphere and water absorbs it. This will then melt the ice as the water around it gets warmer, exposing even more dark ocean to absorb more sunlight.

This is an example of a positive feedback loop. It is a natural mechanism that will increase the effects of the sunlight and melting of the polar ice caps.

Tyson is now in Alaska walking along the edge of the Arctic Ocean. We see time lapse video of the land crumbling as the ice melts.

After commercial, Tyson tells us that when he was born, the shoreline he is walking on was a mile farther out into the ocean and it was breaking off at about 20 feet per year. Now it is being eaten away at about 50 feet per year. The Arctic Ocean is warming at an increasing rate so it is ice free for more of the year. That leaves the coast more exposed to erosion from storms that are getting more powerful - another effect of climate change.

The northern parts of Alaska, Siberia, and Canada are permafrost. This is ground that is frozen year round. It contains lots of organic matter from thousands of years ago. Since these areas are getting warmer faster than anywhere else, the ground is thawing and the content is rotting. It would be as if you unplugged the freezer. The thawing permafrost is releasing large amounts of carbon dioxide and methane - an even more dangerous greenhouse gas - into the atmosphere.

It makes everything warmer in another positive feedback loop.

Tyson says the permafrost holds enough carbon to double the amount of carbon dioxide in the atmosphere. At the rate we’re going, global warming could release most of it by the end of the century. We could be tipping climate change past the point of no return into an unpredictable slide.

Blame it on the Sun

Tyson goes after yet another popular climate denier argument. He concedes that the Earth, air, and water are all getting warmer. Then he says maybe it isn’t us that is doing it. Perhaps it is something else like the Sun.

No, it’s not the Sun. We’ve been monitoring it closely for decades and the solar output has stayed the same. Another thing that points to the Sun not being the cause is that the temperature increases more at night than during the day and more in winter than in summer.

This is what is expected from greenhouse warming, but the opposite of what the Sun would be doing. Tyson says, that beyond a reasonable doubt, we are changing the climate. The Sun isn’t the problem, but it is the solution. We have known this for a long time - much longer than you might think.

Solar Concentrators

We are now in an animation of Paris, France in 1878. The Eiffel Tower has not yet been built. The head of the Statue of Liberty has just been completed. Thousands of exhibitors from around the world covered Paris with their inventions and goods. There is no such thing as electrical appliances yet and it is a hand-crank, horse-drawn world.

We see a man with a crazy mustache. He is a math teacher named Augustin Mouchot. There are no lightbulbs and the automobile is still years away. However, he is dazzling the crowd with his solar concentrator that looks like a big satellite dish attached to a crank. He tells the crowd that his concentrator can collect the free energy of the Sun to create mechanical energy or electrical energy. He proves his point by giving people ice cream out of an electric freezer on a hot day. He says the world will some day run out of fuel, but the Sun will always be there.

Tyson tells us Mouchot brought home the gold medal from the fair. However, the price of coal became so cheap, there was no interest in solar energy and they had no idea the effects of what burning fossil fuels would do. 35 years later, another door opened to an alternative future on the banks of the Nile in Egypt.

After the commercial break, we are in another animation. It is Egypt in 1913. We see Frank Shuman of Philadelphia. He has only had three years of formal schooling, but he is a genius when it comes to innovation. Before he was 30, he had invented safety glass which made him a very rich man. That money allowed him to research his passion which was solar energy. He and his team built a network of solar concentrators. It could power a steam engine.

Shuman was hoping to use the Sun’s power to irrigate the desert and turn it green.

He had invented a practical way to tap the Sun’s energy on an industrial scale, making it even cheaper than coal. Several countries offered him funding to develop his invention in their areas. It was the ideal source of energy in tropical regions where importing coal was very expensive.

Shuman wrote a letter to Scientific American claiming that if he could build an area 150 miles per side in the Sahara Desert, he could create enough energy to power all of the world’s industries. Unfortunately, the market for petroleum had just started to explode and could be used for heating, cars, and shipping. Oil was abundant and cheaper than coal because it was easier to get out of the ground and process. It took 100 men a week to fuel a ship with coal, but with oil, one man can do the job in a single day. World War I broke out and Schuman’s solar collectors were recycled into weapons. It would take another century before his dream was reborn.

Other Clean Energy Sources

There is another source of clean renewable energy available all over the world. The winds themselves are solar powered because our Sun drives the wind and waves. Unlike solar collectors, wind farms take up very little land. If they are offshore, where the winds are strongest, it takes up no land at all. If we can tap even 1% of the winds’ power, we would have enough energy to run our civilization.

More solar energy falls on the Earth in one hour than all of the energy our entire civilization uses in a year. If we could harness even a small amount of the available solar and wind power, we could take care of all of our energy needs forever without adding any carbon to the atmosphere.

Back on the Ship of the Imagination, Tyson tells us it is not too late and there is a bright future out there for us. How does he know? All of us come from a long line of survivors. Our species is nothing if not adaptive. It’s only because our ancestors learned to think long term and act accordingly that we are here at all. The most mythic human accomplishments of all came out of our darkest hour.

The Cold War

After commercial, we see old footage of the Soviet Union and the United States preparing for war. Tyson tells us once there was a world armed with 60,000 hair triggered nuclear weapons. We were locked in a deadly embrace. Both countries vowed they’d rather see everything destroyed than bow to the will of the other. Tyson says when he was 3 years old, the largest man made explosion of all time was detonated by the Soviet Union. That terror has subsided to new fears. The thought that the world’s 2000 largest cities could be obliterated in the space of an afternoon is not one of them. The nuclear rivalry between the United States and the Soviet Union had another outcome.

The Apollo missions to the Moon were an extension of the arms race. Sending people to the Moon requires the same sort of technology needed to send a nuclear warhead halfway around the world to destroy an enemy. We hear an audio clip of President Kennedy’s 1961 speech about sending a man to the Moon by the end of the decade. Tyson says that speech was electrifying, but included no scientific reason to send someone to the Moon. The Apollo missions were conceived to prove we had the power to launch missiles in the same way. A funny thing happened on the way to the Moon. We looked homeward and discovered another world. For the first time, we could step back and see Earth as it is. It is one world, indivisible, and awfully small compared to the size of the universe. Whatever the reason we spent the vast amounts of money and resources for the Apollo missions, it was the clear unity of the Earth that was dividend. What started out as a deadly competition turned into what we can see now as a global community.

We are now on the Ship of Imagination back on Earth. Tyson tells us the Ifugao people of the Philippines invented agriculture during an intermission in the Ice Age. They gave up wandering and hunting and gathering to settle down and produce food. They found a way to harvest 10-100 times more solar energy than the Sun provided for their ancestors. It gave rise to civilization. Now it is our turn to give back.

If life ever existed on Venus, there was no way it could change the runaway greenhouse effect on that world. It was unstoppable and natural. Our world is now. There are no scientific or technological obstacles to protect life on Earth. It only depends on what we value and if we can summon the will to act. The episode closes as we get an upbeat score behind video of the various climates on Earth and what the future could look like. More of Kennedy’s speech is interspersed with the score as the camera pans out.