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[music]

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Narrator: Pulses of laser light. 300,000 per second

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each one represented by a single leaf.

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Flying above a protected area of a Brazilian rainforest,

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NASA scientists measure changes in the canopy to understand how climate change affects

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the amount of carbon stored in the Amazon’s mighty trees.

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They flew the same transect of the forest three times over three years,

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first comparing two fairly normal weather years, 2013 and 2014,

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and then surveying again in 2016,

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after a severe El Niño drought.

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With trees more than 16 stories tall, airborne measurements capture changes

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in forest structure not possible from the ground or from space.

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Lighter areas, seen falling away here,

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represent limbs and whole trees crashing to the ground

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as a result of storms and environmental stress

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As they fall, they take other trees with them.

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In collaboration with Brazilian scientists,

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the team also conducted ground surveys to measure the woody material

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on the forest floor. They found that

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80% of the carbon losses came from the death of larger trees.

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But surprisingly, large trees were not hurt comparatively more by the drought

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than were smaller trees, as had been previously suspected.

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The team also surveyed areas of forest impacted by logging,

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where even more dramatic changes can be seen.

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Researchers will continue to analyze

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the changing climate and human activity affect rainforests