13 Misconceptions About Global Warming

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00:00Let's talk about the science of climate change.

00:04Don't you mean global warming?

00:06How'd you get in here?

00:08I'm the internet. I never left.

00:10Now, why'd you change the name?

00:12Global warming wasn't happening, so you have to call it climate change?

00:15Well, the overall average temperature of the planet is increasing,

00:18so global warming is technically correct.

00:20But that doesn't mean it's going to be warmer everywhere all the time,

00:24and that leads to some confusion.

00:26Like on a cold winter's day, you might say,

00:29So much for global warming.

00:31Exactly.

00:32So the term climate change indicates that the problem is more intense storms,

00:35droughts and floods, ocean acidification,

00:38not just that the globe is warming.

00:41But it's not.

00:42What?

00:43The globe's not warming.

00:44Since when?

00:451995.

00:46Um, that's not how you draw a trend line through data.

00:50If the slope is nil, the climates chill.

00:53You know, 13 of the 14 hottest years occurred this century,

00:57and the graph you're using is old.

00:59It doesn't include satellite data.

01:01If you take that into account, the trend is obviously continuing upwards.

01:05Oh, so now you say it's warming.

01:07In the past, scientists told us it was cooling.

01:10Why can't they just admit that they have no idea what's going on?

01:13It's true.

01:14In the 1970s, there were some papers published predicting cooling.

01:17But over that same time period, there were six times as many papers predicting warming.

01:22So scientists really haven't changed their tune.

01:25Well, just judging by temperatures, I say they're wrong.

01:28The Earth is cooling.

01:29But you don't just have to go by the temperatures.

01:31There are plenty of other signs that the globe is warming.

01:34Like sea levels are rising three millimeters a year.

01:37That's an indication that the oceans are getting warmer and so expanding.

01:41Ice on Antarctica and Greenland is melting at unprecedented rates,

01:45and Arctic sea ice continues to decline.

01:47Nuh-uh, Arctic sea ice increased 40% in the last two years.

01:51That last little uptick?

01:53That's what you focus on?

01:54What about the general downward trend?

01:56It could mean anything.

01:58You know, if the Earth is warming, the most likely source of the problem is the sun.

02:03The sun is getting brighter.

02:04Did you ever think of that?

02:05The sun was getting brighter in the 1930s,

02:08and it probably contributed to some warming then.

02:11But since the 50s, the sun has been getting dimmer,

02:14and temperatures continue to rise.

02:17Oh, so you automatically assume it's man-made CO2.

02:21You know, humans only emit a tiny fraction of the CO2 released into the atmosphere every year.

02:26That's true.

02:27People emit about 30 gigatons,

02:29compared with 780 gigatons from natural land and ocean processes.

02:33So you admit it. Humans aren't the problem.

02:36No.

02:37Before us, the system was in balance,

02:39with the land and oceans absorbing that same amount.

02:42780 gigatons a year.

02:44This balance kept carbon dioxide levels in the atmosphere

02:47between 180 and 280 parts per million for 800,000 years.

02:52Now it's at 400 parts per million and still rising.

02:55But our small contribution couldn't have caused that.

02:58Well, the amount of CO2 in the atmosphere is increasing by about 15 gigatons,

03:02or two parts per million, every year.

03:04But how do you know that's man-made CO2?

03:07Because the isotope carbon-13 is less common in fossil fuels than it is naturally in the atmosphere.

03:13And over time, we're seeing the concentrations of carbon-13 are decreasing.

03:18But volcanoes emit way more CO2 than humans.

03:21No, they don't.

03:22They emit about 0.25 gigatons annually.

03:25That's less than 1% as much as humans.

03:27Okay, well, even if we are responsible for the rise in CO2,

03:30it doesn't matter because water is by far the most potent greenhouse gas.

03:35Yes, it is.

03:36I win.

03:37No, you don't.

03:38Water in the atmosphere is increasing as well.

03:41But that can't be due to human activity.

03:43The only way for the atmosphere to hold more water vapor is if it gets warmer.

03:47So...

03:48Hang on.

03:49You're not saying...

03:50Yes.

03:51It all comes back to CO2.

03:53A doubling of CO2 on its own would increase the temperature of the globe by about 1 degree Celsius.

03:59But that warming means there will be more water vapor in the atmosphere and ice will melt,

04:04reducing the reflectivity of Earth's surface.

04:06So it's a positive feedback loop which a bunch of different sources of evidence all indicate

04:11will lead to about a 3 degree Celsius rise in temperature.

04:15But if this is true, why have all the predictions failed?

04:18In actuality, most of the predictions show remarkable agreement with observations.

04:22But you're probably thinking of the model from 1988, back when we thought climate sensitivity was higher.

04:28If you rerun that model with 3 degrees of warming for every doubling of CO2,

04:32the predictions match exactly the warming that we've observed.

04:35But the Earth has warmed and cooled in the past.

04:38So, who was releasing CO2 back then?

04:41Aliens?

04:42We understand that past changes in the climate were triggered at regular intervals by Milankovitch cycles.

04:47That is, the periodic oscillation of the Earth's tilt, precession of the tilt, and stretching and squishing of Earth's elliptical orbit.

04:55During every warming cycle, CO2 and temperature rise together.

04:58Ah, 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.

05:06The CO2 doesn't cause the first warming.

05:09The Milankovitch cycles change the way the sunlight hits the Earth.

05:13And that causes a little bit of warming, decreasing the solubility of CO2 in the oceans.

05:18So some of that CO2 is released, and that is a positive feedback loop which amplifies the warming.

05:24In fact, over 90% of the temperature increase happens after the CO2 starts to rise.

05:29Let's say you're right, and the CO2 we're releasing is warming the planet.

05:34What's so bad about that?

05:35The planet gets a little warmer, big deal.

05:37I'm not claiming it's going to be some sort of crazy catastrophe, but we are going to get more intense storms,

05:42more droughts and floods, the oceans will become more acidic, sea levels will rise,

05:47and my point is it would be better for all species on this planet and probably cheaper for us

05:52if we just started reducing emissions now than if we wait and pay the consequences later.

05:57No thanks.

05:58Why are you wearing sunglasses?

06:05Global warming?

06:10This episode of Veritasium was supported by Audible.com, a leading provider of audiobooks

06:14with over 150,000 titles in all areas of literature, including fiction, nonfiction, and periodicals.

06:20This week I wanted to recommend the book Merchants of Doubt, which is about scientists

06:25who have spread misinformation about certain topics like how cigarettes cause lung cancer,

06:30or how CFCs cause the ozone hole, or now how CO2 is causing the planet to warm.

06:35So if you want to find out more about that, you can download this book by going to audible.com slash veritasium,

06:40or you can pick any other book of your choosing for a one month free trial.

06:43So I want to thank Audible for supporting me and I want to thank you for watching.

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