[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:06.37,0:00:07.100,Default,,0000,0000,0000,,To understand climate change,
Dialogue: 0,0:00:07.100,0:00:09.75,Default,,0000,0000,0000,,think of the game Tetris.
Dialogue: 0,0:00:09.75,0:00:13.78,Default,,0000,0000,0000,,For eons Earth has played a version of this game with blocks of carbon.
Dialogue: 0,0:00:13.78,0:00:17.67,Default,,0000,0000,0000,,They enter the atmosphere as carbon dioxide gas from volcanoes,
Dialogue: 0,0:00:17.67,0:00:19.34,Default,,0000,0000,0000,,decaying plant matter,
Dialogue: 0,0:00:19.34,0:00:20.51,Default,,0000,0000,0000,,breathing creatures
Dialogue: 0,0:00:20.51,0:00:22.01,Default,,0000,0000,0000,,and the surface of the sea.
Dialogue: 0,0:00:22.01,0:00:25.93,Default,,0000,0000,0000,,And they leave the atmosphere when they're used by plants during photosynthesis,
Dialogue: 0,0:00:25.93,0:00:27.62,Default,,0000,0000,0000,,absorbed back into the ocean
Dialogue: 0,0:00:27.62,0:00:29.81,Default,,0000,0000,0000,,or stored in soil and sediment.
Dialogue: 0,0:00:29.81,0:00:32.18,Default,,0000,0000,0000,,This game of Tetris is called the carbon cycle,
Dialogue: 0,0:00:32.18,0:00:34.31,Default,,0000,0000,0000,,and it's the engine of life on Earth.
Dialogue: 0,0:00:34.31,0:00:36.70,Default,,0000,0000,0000,,What's the connection to climate?
Dialogue: 0,0:00:36.70,0:00:39.15,Default,,0000,0000,0000,,Well, when that carbon dioxide is in the air,
Dialogue: 0,0:00:39.15,0:00:40.90,Default,,0000,0000,0000,,waiting to be reabsorbed,
Dialogue: 0,0:00:40.90,0:00:42.78,Default,,0000,0000,0000,,it traps a portion of the sun's heat,
Dialogue: 0,0:00:42.78,0:00:44.78,Default,,0000,0000,0000,,which would otherwise escape to space.
Dialogue: 0,0:00:44.78,0:00:47.84,Default,,0000,0000,0000,,That's why carbon dioxide is called a greenhouse gas.
Dialogue: 0,0:00:47.84,0:00:49.54,Default,,0000,0000,0000,,It creates a blanket of warmth,
Dialogue: 0,0:00:49.54,0:00:51.22,Default,,0000,0000,0000,,known as the greenhouse effect,
Dialogue: 0,0:00:51.22,0:00:53.50,Default,,0000,0000,0000,,that keeps our Earth from freezing like Mars.
Dialogue: 0,0:00:53.50,0:00:57.88,Default,,0000,0000,0000,,The more carbon dioxide blocks hang out in the atmosphere waiting to be cleared,
Dialogue: 0,0:00:57.88,0:00:59.92,Default,,0000,0000,0000,,the warmer Earth becomes.
Dialogue: 0,0:00:59.92,0:01:01.88,Default,,0000,0000,0000,,Though the amount of carbon in the atmosphere
Dialogue: 0,0:01:01.88,0:01:05.01,Default,,0000,0000,0000,,has varied through ice ages and astroid impacts,
Dialogue: 0,0:01:05.01,0:01:09.38,Default,,0000,0000,0000,,over the past 8,000 years the stable climate we know took shape,
Dialogue: 0,0:01:09.38,0:01:12.22,Default,,0000,0000,0000,,allowing human civilization to thrive.
Dialogue: 0,0:01:12.22,0:01:13.97,Default,,0000,0000,0000,,But about 200 years ago,
Dialogue: 0,0:01:13.97,0:01:17.47,Default,,0000,0000,0000,,we began digging up that old carbon that had been stored in the soil.
Dialogue: 0,0:01:17.47,0:01:20.94,Default,,0000,0000,0000,,These fossil fuels, coal, oil and natural gas
Dialogue: 0,0:01:20.94,0:01:23.61,Default,,0000,0000,0000,,are made from the buried remains of plants and animals
Dialogue: 0,0:01:23.61,0:01:26.91,Default,,0000,0000,0000,,that died long before humans evolved.
Dialogue: 0,0:01:26.91,0:01:29.14,Default,,0000,0000,0000,,The energy stored inside them was able to power
Dialogue: 0,0:01:29.14,0:01:32.04,Default,,0000,0000,0000,,our factories, cars and power plants.
Dialogue: 0,0:01:32.04,0:01:37.08,Default,,0000,0000,0000,,But burning these fuels also injected new carbon blocks into Earth's Tetris game.
Dialogue: 0,0:01:37.08,0:01:40.09,Default,,0000,0000,0000,,At the same time, we cleared forests for agriculture,
Dialogue: 0,0:01:40.09,0:01:43.38,Default,,0000,0000,0000,,reducing the earth's ability to remove the blocks.
Dialogue: 0,0:01:43.38,0:01:46.72,Default,,0000,0000,0000,,And since 1750, the amount of carbon in the atmosophere
Dialogue: 0,0:01:46.72,0:01:48.72,Default,,0000,0000,0000,,has increased by 40%,
Dialogue: 0,0:01:48.72,0:01:51.38,Default,,0000,0000,0000,,and shows no sign of slowing.
Dialogue: 0,0:01:51.38,0:01:53.88,Default,,0000,0000,0000,,Just like in Tetris, the more blocks pile up,
Dialogue: 0,0:01:53.88,0:01:56.77,Default,,0000,0000,0000,,the harder it becomes to restore stability.
Dialogue: 0,0:01:56.77,0:01:58.94,Default,,0000,0000,0000,,The extra carbon dioxide in the atmosphere
Dialogue: 0,0:01:58.94,9:59:59.99,Default,,0000,0000,0000,,accelerates the Greenhouse Effect
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,by trapping more heat near the surface
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,and causing polar ice caps to melt.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,And the more they melt, the less sunlight they're able to reflect,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,making the oceans warm even faster.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Sea levels rise, coastal populations are threatened with flooding,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,natural ecosystems are disrupted,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,and the weather becomes more extreme over time.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,Climate change may effect different people and places in different ways.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,But, ultimately, it's a game that we're all stuck playing.
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,And unlike in Tetris,
Dialogue: 0,9:59:59.99,9:59:59.99,Default,,0000,0000,0000,,we won't get a chance to start over and try again.