读英文报-人类对环境影响追溯到11500年前

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From USA Today, June 8, 2017

Humans were already changing the environment 11,500 years ago

Man-made environmental change isn't new: A study found human activities such as farming and logging （伐木）led to erosion （腐蚀） around the Dead Sea some 11,500 years ago, the earliest ever discovered.

Scientists from Israel's Tel Aviv（特拉维夫） University took a core sample — a long, cylindrical section of rock and dirt — from under the Dead Sea. The sample gave the team an accurate sediment （沉淀物）record of the past 220,000 years.

Looking at a sample from 11,500 years ago, the researchers detected rates of erosion that could not have occurred naturally.

"Natural vegetation was replaced by crops, animals were domesticated, grazing （牧场） reduced the natural plant cover, and deforestation provided more area for grazing," said geologist Shmuel Marco, who led the study.

The researchers argue human activity at that time disrupted the natural surface around the Dead Sea, bringing about intensified erosion, Marco said. "We see it in the form of triple and even four times the increase of the sediment supply to the lake.”

The research took place as part of a Dead Sea deep drilling project, which harnessed a 1,500-foot-deep drill core to delve into the earth. The Dead Sea area is an excellent natural laboratory for studying geology and climatology, because it offers "a rare combination of well-documented substantial climate change, intense tectonics （构造地质学）and abundant archaeological evidence for past human activity," the study said.