What Is Climate Change? — Transcript

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1. 0:00Climate change is intimate and personal.
2. 0:02At this point, it affects you every time
3. 0:05you go to the grocery store or fill your
4. 0:07gas tank or vote or flush the toilet or
5. 0:10put on your long underwear for a later
6. 0:11than usual snowfall. And every year, it
7. 0:15will affect you more. At the same time,
8. 0:17it's cosmically impersonal. It involves
9. 0:20gases and rocks and chemicals that have
10. 0:22been operating in relationship for
11. 0:24billions of years before there are any
12. 0:27persons or underwear to contend with at
13. 0:29all. In between these two levels, the
14. 0:31sphere of your bedroom and the sheer
15. 0:33vastness of the history of the universe,
16. 0:36there are still other vantage points to
17. 0:38look at climate change from. Climate
18. 0:39change is a collective and a systemic
19. 0:42problem dealing not just with
20. 0:43individuals but with entire populations
21. 0:46and global systems like energy grids and
22. 0:49international trade. So we have to kind
23. 0:50of zoom in and zoom out travel through
24. 0:53time and space. And as centuries of mad
25. 0:56scientists have taught us, it's not an
26. 0:58easy task. Hi. Hi. I'm M. Jackson and
27. 1:00this is Crash Course Climate and Energy.
28. 1:12Think about it. There's the human
29. 1:15lifetime where we all live where there's
30. 1:18weather and politics and hard choices
31. 1:20and beautiful moments of collaboration.
32. 1:23And then there's hundreds of years that
33. 1:25contain full human lifetimes, the
34. 1:28generations yet to come that will be
35. 1:29impacted by the climate related choices
36. 1:32of today and yesterday. On top of that,
37. 1:34there's the multibillionyear timeline of
38. 1:37Earth, which is entirely alien to our
39. 1:41human perception. But we won the
40. 1:43planetary lottery with our habitable
41. 1:45Earth, the only one out of the thousands
42. 1:48of planets known in our galaxy where
43. 1:50life like ours can survive. So, yes,
44. 1:54truly understanding climate change
45. 1:55across all these timelines is tough.
46. 1:58Sometimes it's downright mind-blowing,
47. 2:01but it's on us to grapple with what's
48. 2:03happening, not just to the Earth, but to
49. 2:06all of its inhabitants as the climate
50. 2:08changes faster now than ever before. And
51. 2:11I mean that the Earth's climate has
52. 2:14never changed this fast. Let's start at
53. 2:17the human scale. A single human
54. 2:19actually, a human named Ununice Foot. In
55. 2:22the 1850s, she was reading an issue of
56. 2:24Scientific American and became curious.
57. 2:27And like any good scientist, she nerded
58. 2:30out about how the sun heats up the
59. 2:31Earth. She wanted to see how density and
60. 2:34the mixture of gases in the air affected
61. 2:36how much heat the atmosphere could hold
62. 2:37on to. And she tested that with a series
63. 2:39of experiments. In one of them, she
64. 2:41noticed that high concentrations of
65. 2:43so-called carbonic acid gas made the air
66. 2:46heat up faster and stay warmer for
67. 2:47longer. Based on her experiments, she
68. 2:50concluded that if the atmosphere ever
69. 2:51contained more of this gas, then we
70. 2:54might also expect the global temperature
71. 2:56to be higher. Today we know carbonic
72. 2:59acid gas as carbon dioxide. So foot
73. 3:02became one of the first scientists to
74. 3:04make the link between carbon dioxide and
75. 3:07atmospheric heating. It was one of the
76. 3:09first experiments demonstrating the
77. 3:11greenhouse effect. You know that wash of
78. 3:14warm air you get when you go into a
79. 3:16greenhouse? It happens because glass
80. 3:18panels do a great job of trapping the
81. 3:20sun's heat to nurture your tomato
82. 3:21plants. Well, imagine scaling that up to
83. 3:23the entire earth. But instead of glass
84. 3:26trapping heat, it's gas. Specifically,
85. 3:29gases like carbon dioxide, methane, and
86. 3:32water vapor, which are known
87. 3:34collectively as greenhouse gases. You
88. 3:36can think of the greenhouse effect like
89. 3:38a giant volleyball game. Between the sun
90. 3:41and the surface of the Earth, where the
91. 3:43atmosphere is the net, and instead of
92. 3:45one ball,
93. 3:47there are trillions. The sun serves
94. 3:49these balls as different forms of
95. 3:50radiation. What you and I might
96. 3:52experience is visible light, UV light,
97. 3:54or infrared radiation, which is just
98. 3:57another fancy way to say heat. Some of
99. 3:59that radiation makes it over the
100. 4:01metaphorical neck. It passes through the
101. 4:03atmosphere and hits the planet's
102. 4:05surface. A lot of that energy is then
103. 4:07absorbed by the land and the sea.
104. 4:10Hey, where'd my ball go? The land and
105. 4:12sea naturally reflect back some of their
106. 4:14[music] heat energy. But with the
107. 4:15greenhouse effect, more and more heat
108. 4:18energy is getting trapped by the net.
109. 4:20Then the energy gets absorbed by the
110. 4:23atmosphere instead of escaping into
111. 4:24space, the other side of the court. That
112. 4:27causes the energy to bounce back down
113. 4:28towards the surface of the Earth,
114. 4:30warming it up. The Earth is losing the
115. 4:32cosmic volleyball game, returning fewer
116. 4:34and fewer of the sun's serves every year
117. 4:37as the amount of greenhouse gases goes
118. 4:39up. Now, instead of having a constant
119. 4:41number of balls on our side of the
120. 4:42court, we have more each day. Although
121. 4:45greenhouse gases only make up a small
122. 4:47portion of the atmosphere, they play a
123. 4:49major role in controlling our planet's
124. 4:52overall temperature and its climate.
125. 4:54Even increasing the amount of carbon
126. 4:56dioxide in the atmosphere by just a few
127. 4:58parts per million can lead to
128. 5:00temperature changes that fuel severe
129. 5:01weather, melt ice caps, and make life on
130. 5:04Earth generally more difficult. How do
131. 5:06we know this? By studying the chemistry
132. 5:09of rocks and fossils that are hundreds
133. 5:10of millions of years old, scientists can
134. 5:13piece together how ancient temperatures
135. 5:15fluctuated and how in parallel the
136. 5:18composition of our atmosphere
137. 5:19fluctuated. But if we want a more recent
138. 5:21picture, we can get an even better
139. 5:23record from, drum roll, glaciers. ice
140. 5:27cores from Greenland and Antarctic ice
141. 5:29caps have preserved tiny bubbles of our
142. 5:32actual atmosphere from hundreds of
143. 5:34thousands of years ago that today
144. 5:37scientists like me can study. What all
145. 5:39these records tell us is that throughout
146. 5:41Earth's 4 and a half billion birthdays,
147. 5:44at times it's been a lot colder than
148. 5:45today and at other times it's been a lot
149. 5:48warmer. And guess what is one of the
150. 5:50most consistent variables that leads to
151. 5:51that temperature fluctuation? You got
152. 5:53it. The amount of greenhouse gases in
153. 5:56the atmosphere. So, let's travel through
154. 5:57time and space to see what things looked
155. 6:00like when those bubbles were in their
156. 6:01prime. Let's go to the thought bubble.
157. 6:03Back when Earth was formed about 4 and a
158. 6:05half billion years ago, it was hot. And
159. 6:08I don't mean eating your body weight and
160. 6:10popsicles hot. I mean covered in an
161. 6:13ocean of molten rock. Hot. Earth was
162. 6:16still being pummeled by debris from the
163. 6:18formation of the solar system. And
164. 6:19volcanoes were spewing out a whole lot
165. 6:21of carbon dioxide, helping to trap all
166. 6:24that heat. Over millions and millions of
167. 6:25years, the molten rock solidified,
168. 6:28forming a solid surface on the Earth.
169. 6:30And millions and millions of years after
170. 6:32that, the primitive ocean formed. As a
171. 6:35result, the Earth continued to gradually
172. 6:37cool down. And then a couple of times
173. 6:39throughout its early history, before
174. 6:41animals we'd recognize today even
175. 6:43evolved, things got really cold. So cold
176. 6:46that researchers think ice sheets and
177. 6:48sea ice extended all the way to the
178. 6:50equator. These are called snowball Earth
179. 6:52periods. And scientists have a few ideas
180. 6:54about why they happened. Ranging from
181. 6:57volcanic ash blocking out the sun to a
182. 7:00drop in carbon levels, which was
183. 7:02possibly a result of things like early
184. 7:04plants sucking in the gas for
185. 7:06photosynthesis. After that, it got hot
186. 7:08again a few times over the next half a
187. 7:10billion years. Most recently about 56
188. 7:13million years ago. Back then, average
189. 7:15global temperatures were as high as 23°
190. 7:18C. There would have been no ice at the
191. 7:20poles and palm trees and crocodiles
192. 7:22could be found at the Arctic. If humans
193. 7:24have been around, we'd probably have
194. 7:25been building tropical water parks at
195. 7:27the North Pole. Because if there's a one
196. 7:29thing we know for certain about our
197. 7:31species, we love a twisty slide. But
198. 7:33maybe thankfully for everyone, modern
199. 7:35humans wouldn't evolve for over 55
200. 7:38million years. We know our fragile
201. 7:40civilizations, water parks and all,
202. 7:42wouldn't have stood a chance for these
203. 7:43dramatic shifts in Earth's climate.
204. 7:45Thanks, thought bubble. Now, luckily for
205. 7:47the human species, the ice core record
206. 7:49of the last 800,000 years reveals much
207. 7:52gentler temperature fluctuations,
208. 7:55at least until we get to the last 200
209. 7:57years. In just a couple of centuries,
210. 7:59temperatures have gone up faster than
211. 8:01ever seen before in recorded history.
212. 8:03And the average temperature on Earth
213. 8:05today is the highest it's been in a
214. 8:07100,000 years. We've never experienced
215. 8:09this before. Even when Earth emerged
216. 8:11from previous ice ages, the planet
217. 8:13warmed up at a rate of only about 1° C
218. 8:16per 1,000 years. But today, global
219. 8:20temperatures have shot up by.7° C per
220. 8:23100 years. That's almost 10 times
221. 8:26faster. So, it changed in the last 200
222. 8:28years. Well, there was one big thing,
223. 8:32the industrial revolution. When humans
224. 8:35discovered we could do things a lot
225. 8:36faster and with a lot less effort by
226. 8:39burning fossil fuels. Fossil fuels like
227. 8:42coal, oil, and gas provided a reliable
228. 8:45source of heat and electricity. So when
229. 8:47we went for them in a big way, they
230. 8:50helped to shape our modern civilization.
231. 8:51And that's how you ended up here
232. 8:53watching this video on an internet
233. 8:55largely powered by fossil fuels. But
234. 8:57burning these fuels comes at a cost. It
235. 9:00releases carbon dioxide. And as we've
236. 9:02burned more of them to keep up with our
237. 9:03growing population and our energy needs,
238. 9:06our emissions have gone up as well. And
239. 9:09that volleyball match keeps getting
240. 9:11harder to watch. So this is what we
241. 9:13know. The average global temperature has
242. 9:15gone up and carbon dioxide emissions
243. 9:17have gone up. And we know that carbon
244. 9:19dioxide is a heat trapping greenhouse
245. 9:21gas. As scientists have put those things
246. 9:23together, it's led them to an
247. 9:25inescapable conclusion. Human activity
248. 9:29has caused the Earth to warm up at an
249. 9:31unprecedented rate. We can measure this
250. 9:34warming with every passing month, but
251. 9:38its global effects aren't as
252. 9:39straightforward. There's a big
253. 9:41difference between what scientists study
254. 9:42as climate and what you and I experience
255. 9:45as weather. Weather is where we live.
256. 9:47So, when you wake up in Istanbul in
257. 9:49March and see that it's weirdly cold and
258. 9:51also snowing, that's weather. And
259. 9:54although it may seem at odds with a
260. 9:56warming planet, it's happening as a
261. 9:58result of climate shifts elsewhere on
262. 10:00Earth. Climate deals with multi-deade
263. 10:03broadscale trends in things like
264. 10:05temperature and precipitation patterns
265. 10:07across the globe. But since climate and
266. 10:09weather are so closely linked, it can
267. 10:12get complicated. For instance,
268. 10:14scientists agree that atypical extreme
269. 10:16weather events are more likely when the
270. 10:18planet's climate is warmer. But that's
271. 10:21only because there's more heat trapped
272. 10:22in the oceans and atmosphere to power
273. 10:24these weather events. Meteorologists are
274. 10:26constantly working to improve their
275. 10:28forecasting models for both short-term
276. 10:30weather and long-term climate based on
277. 10:32how much energy is in the atmosphere. By
278. 10:34comparing and refining their models,
279. 10:36scientists can now reliably predict some
280. 10:38general outcomes if the current pace of
281. 10:40climate change continues. And it might
282. 10:42come as no surprise that it's not
283. 10:44looking good. We can expect and are
284. 10:47currently already seeing in some cases
285. 10:50melting ice caps, rising sea levels,
286. 10:53shifts in agricultural productivity,
287. 10:55more storms, more floods, more droughts.
288. 10:57Basically, climate change amplifies any
289. 11:00weather you might typically experience.
290. 11:02And these effects can ultimately lead to
291. 11:05global economic losses, displacement of
292. 11:07vulnerable communities, and almost
293. 11:09inevitably geopolitical tensions.
294. 11:12Changing climate and changing weather
295. 11:13patterns will have a significant impact
296. 11:15on everyone all over the globe. But not
297. 11:18everyone will experience the same
298. 11:20consequences of those impacts or be able
299. 11:23to adapt to them in the same way. And
300. 11:25those who have been and may continue to
301. 11:27face some of the most severe
302. 11:29consequences are often in regions least
303. 11:32responsible for the greenhouse gas
304. 11:34emissions driving global climate change.
305. 11:36So the question becomes, what do we owe
306. 11:38each other as roommates on this
307. 11:40singularly lucky planet where we live
308. 11:43alongside tomato plants and vibrant blue
309. 11:45glaciers and frillenecked lizards and
310. 11:47blobfishes and incredible human
311. 11:49creativity. We know temperatures have
312. 11:51fluctuated dramatically over Earth's
313. 11:53long history. But by burning so many
314. 11:55fossil fuels and flooding the atmosphere
315. 11:57with gases like carbon dioxide, we also
316. 12:00know we're causing temperatures to rise
317. 12:03faster than ever. And while this is a
318. 12:05massive challenge that won't have easy
319. 12:07solutions, there are lots of fascinating
320. 12:09ideas for how humans might tackle
321. 12:11climate change from a number of
322. 12:12different directions. We don't know all
323. 12:14the answers, and we can never return to
324. 12:16the Earth of 250 years ago. But we'll
325. 12:19explore the many cobblestones that might
326. 12:22make a pathway forward towards a new way
327. 12:24of living together on our Earth, even if
328. 12:27it's a bit bumpy.
329. 12:33Honey,