13 Misconceptions About Global Warming

[Applause]

Let's talk about the science of climate change.

"Don't you mean global warming?"

"How'd you get in here?"

"I'm the Internet; I never left. Now, why did you change the name?"

"Global warming wasn't happening, so you have to call it climate change."

"Well, the overall average temperature of the planet is increasing, so global warming is technically correct. But that doesn't mean it's going to be warmer everywhere all the time, and that leads to some confusion. Like on a cold winter's day, you might say, 'So much for global warming!'"

"Exactly. So the term climate change indicates that the problem is more intense storms, droughts, and floods. Ocean acidification, not just that the globe is warming."

"But it's not—what? The globe's not warming?"

"Since when?"

"1995."

"That's not how you draw a trendline through data. If the slope is nil, the climate's chill."

"You know, 13 of the 14 years occurred this century, and the graph you're using is old. It doesn't include satellite data."

"If you take that into account, the trend is obviously continuing upwards."

"Oh, so now you say it's warming? In the past, scientists told us it was cooling. Why can't they just admit that they have no idea what's going on?"

"It's true in the 1970s there were some papers published predicting cooling, but over that same time period, there were six times as many papers predicting warming. So scientists really haven't changed their tune."

"Well, just judging by temperatures, I say they're wrong. The Earth is cooling."

"But you don't just have to go by the temperatures. There are plenty of other signs that the globe is warming, like sea levels are rising three millimeters a year. That's an indication that the oceans are getting warmer, and so expanding. Ice on Antarctica and Greenland is melting at unprecedented rates and Arctic sea ice continues to decline."

"Nah-uh! Arctic sea ice increased 40% in the last two years."

"That last little uptick—that's what you focus on? What about the general downward trend? That could mean anything."

"You know, if the Earth is warming, the most likely source of the problem is the Sun. The Sun is getting brighter."

"Did you ever think of that?"

"The Sun was getting brighter in the 1930s, and it probably contributed to some warming then. But since the 50s, the Sun has been getting dimmer, and temperatures continue to rise."

"Oh, see? You automatically assume it's man-made CO2."

"You know, humans only emit a tiny fraction of the CO2 released into the atmosphere every year."

"That's true. People emit about 30 Giga tons compared with 780 Giga tons from natural land and ocean processes."

"So you admit it, humans aren't the problem?"

"No. Before us, the system was in balance, with the land and oceans absorbing that same amount, 780 Giga tons a year. This balance kept carbon dioxide levels in the atmosphere between 180 and 280 parts per million for 800,000 years. Now it's at 400 parts per million and still rising."

"But our small contribution couldn't have caused that?"

"Well, the amount of CO2 in the atmosphere is increasing by about 15 Giga tons, or 2 parts per million every year."

"But how do you know that's man-made CO2?"

"Because the isotope carbon 13 is less common in fossil fuels than it is naturally in the atmosphere, and over time, we're seeing the concentrations of carbon 13 are decreasing."

"But volcanoes emit way more CO2 than humans."

"No, they don't. They emit about 0.25 Giga tons annually; that's less than 1% as much as humans."

"Ok, well, even if we are responsible for the rise in CO2, it doesn't matter, because water is by far the most potent greenhouse gas."

"Yes, it is. I win."

"No, you don't. Water in the atmosphere is increasing as well, but that can't be due to human activity. The only way for the atmosphere to hold more water vapor is if it gets warmer."

"So hang on, you're not saying yes, it all comes back to CO2?"

"A doubling of CO2 on its own would increase the temperature of the globe by about 1 degree Celsius. But that warming means there'll be more water vapor in the atmosphere, and ice will melt, reducing the reflectivity of Earth's surface. So it's a positive feedback loop, which a bunch of different sources of evidence all indicate will lead to about a 3 degrees Celsius rise in temperature."

"But if this is true, why have all the predictions failed?"

"In actuality, most of the predictions show remarkable agreement with observations. But you're probably thinking of the model from 1988, back when we thought climate sensitivity was higher. If you rerun that model with three degrees of warming for every doubling of CO2, the predictions match exactly the warming that we've observed."

"But the Earth has warmed and cooled in the past, so who is releasing CO2 back then?"

"Aliens? We understand that past changes in the climate were triggered at regular intervals by Milankovitch cycles. That is the periodic oscillation of the Earth's tilt, precession of the tilt, and stretching and squashing of Earth's elliptical orbit. During every warming cycle, CO2 and temperature rise together."

"Ah, but if you look closely at that graph, you'll see that CO2 lags behind the temperature rise, so it can't be causing the warming."

"The CO2 doesn't cause the first warming. The Milankovitch cycles changed the way the sunlight hits the Earth, and that causes a little bit of warming, decreasing the solubility of CO2 in the oceans. So some of that CO2 is released, and that is a positive feedback loop which amplifies the warming. In fact, over 90% of the temperature increase happens after the CO2 starts to rise."

"Let's say you're right, and the CO2 we're releasing is warming the planet. What's so bad about that? Planet gets a little warmer, big deal."

"I'm not claiming it's gonna be some sort of crazy catastrophe, but we are gonna get more intense storms, more droughts and floods. The oceans will become more acidic, sea levels will rise, and my point is it would be better for all species on this planet. And probably cheaper for us if we just started reducing emissions now than if we wait and pay the consequences later."

"No thanks."

"Why are you wearing sunglasses?"

[Music]

"Global warming, this episode of Veritasium was supported by audible.com, a leading provider of audiobooks with over 150,000 titles in all areas of literature, including fiction, nonfiction and periodicals. This week I wanted to recommend the book 'Merchants of Doubt,' which is about scientists who have spread misinformation about certain topics, like how cigarettes cause lung cancer, or how CFCs caused the ozone hole, or now how CO2 is causing the planet to warm. So if you want to find out more about that, you can download this book by going to audible.com/veritasium, or you can pick any other book of your choosing for a one-month free trial. So I want to thank Audible for supporting me, and I want to thank you for watching."