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Ancient trees are revealing new findings about human-caused drought

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NASA has only been studying soil moisture from space since 1980 

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Which meant that scientists needed an older, 

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but reliable record to understand our past climate

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Researchers can use tree data to map droughts as far back as 1400

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The result?

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We now know that greenhouse gases caused by humans 

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have been affecting global drought since the early 20th century

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How do we know?

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Tree ring data is amazingly accurate

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The rings are thinner in years when it’s dry and may not grow at all in stressful conditions like drought

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Look Closer: Signal for human-caused climate change

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This is the first study to provide historical evidence connecting human-generated emissions

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and drought at near-global scales between 1900 and 2005

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Together, modern soil moisture measurements and tree ring-based records

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of the past create a more complete data set

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Verifying the accuracy of climate models that predict more frequent drought in the near future

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