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To understand climate change,

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think of the game "Tetris."

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For eons, Earth has played a version of this game with blocks of carbon.

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They enter the atmosphere as carbon dioxide gas from volcanoes,

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decaying plant matter,

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breathing creatures

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and the surface of the sea.

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And they leave the atmosphere when they're used by plants during photosynthesis,

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absorbed back into the ocean,

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or stored in soil and sediment.

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This game of Tetris is called the carbon cycle,

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and it's the engine of life on Earth.

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What's the connection to climate?

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Well, when that carbon dioxide is in the air,

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waiting to be reabsorbed,

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it traps a portion of the sun's heat,

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which would otherwise escape to space.

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That's why carbon dioxide is called a greenhouse gas.

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It creates a blanket of warmth,

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known as the greenhouse effect,

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that keeps our Earth from freezing like Mars.

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The more carbon dioxide blocks hang out in the atmosphere waiting to be cleared,

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the warmer Earth becomes.

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Though the amount of carbon in the atmosphere

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has varied through ice ages and astroid impacts,

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over the past 8,000 years the stable climate we know took shape,

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allowing human civilization to thrive.

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But about 200 years ago,

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we began digging up that old carbon that had been stored in the soil.

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These fossil fuels, coal, oil and natural gas

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are made from the buried remains of plants and animals

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that died long before humans evolved.

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The energy stored inside them was able to power

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our factories, cars and power plants.

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But burning these fuels also injected new carbon blocks into Earth's Tetris game.

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At the same time, we cleared forests for agriculture,

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reducing the Earth's ability to remove the blocks.

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And since 1750, the amount of carbon in the atmosophere

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has increased by 40%,

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and shows no sign of slowing.

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Just like in Tetris, the more blocks pile up,

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the harder it becomes to restore stability.

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The extra carbon dioxide in the atmosphere

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accelerates the greenhouse effect

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by trapping more heat near the surface

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and causing polar ice caps to melt.

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And the more they melt, the less sunlight they're able to reflect,

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making the oceans warm even faster.

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Sea levels rise, coastal populations are threatened with flooding,

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natural ecosystems are disrupted,

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and the weather becomes more extreme over time.

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Climate change may effect different people and places in different ways.

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But, ultimately, it's a game that we're all stuck playing.

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And unlike in Tetris,

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we won't get a chance to start over and try again.