Dave Meko, a scientist at the University of Arizona, noticed that from 1999 to the following years, it became drier and drier.
亚利桑那大学的科学家戴夫·梅科注意到，从1999年到接下来的几年里，天气变得越来越干燥。
And water levels in the huge Colorado River were dropping rapidly.
而且巨大的 Colorado 河的水位正在迅速下降。
This was the beginning of a serious drought.
这是一场严重干旱的开始。
Everyone began asking, "How long will it last?"
每个人都开始问：“这会持续多久？”
Meko believed that he could find the answer in the trees.
梅科相信他可以在树木中找到答案。
Meko is a tree-ring expert.
梅科是一位树木年轮专家。
He studies the rings within a tree to find information about climate change.
他研究树木内部的年轮，以寻找关于气候变化的信息。
Each year, a tree adds a new layer of wood.
每年，树木都会增加一层新的木质。
These layers look like a series of rings.
这些层看起来就像一系列的圆圈。
During times of heavy rainfall, the ring is wide.
在降雨量大的时期，年轮是宽的。
When there is a shortage of water, the ring is narrow.
当缺水时，年轮是窄的。
These rings are nature's record of rainfall and climate change.
这些年轮是自然界对降雨和气候变化的记录。
Meko and his team quickly started a new research project.
梅科和他的团队迅速启动了一个新的研究项目。
Their goal was to find out how long previous droughts lasted.
他们的目标是查明以前的干旱持续了多久。
The team collected as many old wood samples as possible.
该团队收集了尽可能多的老木材样本。
They tested wood samples from 1,200 years ago until the present.
他们检测了从1200年前直到现在的木材样本。
When they examined the rings, the news about rainfall in the past was not good.
当他们检查年轮时，关于过去降雨的消息并不好。
Meko's research showed that the 20th century was an unusually wet time.
梅科的研究表明，20世纪是一个异常潮湿的时间。
Trees from this period had wide, healthy rings.
这一时期的树木有着宽阔而健康的年轮。
Rain was plentiful during that century and millions of people moved to the region.
在那个世纪里降雨是充沛的，数以百万计的人搬到了这个地区。
Before that time, however, the rings showed that droughts occurred on a regular basis.
然而，在那段时间之前，年轮显示干旱是定期发生的。
In fact, drought was part of the usual climate pattern.
事实上，干旱是通常气候模式的一部分。
There were serious droughts in the 900s, the 1100s and the late 1200s.
在900年代、1100年代和1200年代后期都发生过严重的干旱。
Human history seems to support Meko's findings.
人类历史似乎支持梅科的发现。
The native Anasazi lived in this area for hundreds of years, starting around 500 AD.
土著阿纳萨齐人在这片地区生活了数百年，大约始于公元500年。
They were farmers and depended on water to grow their crops.
他们是农民，依靠水来种植他们的庄稼。
However, at the end of the 13th century, the Anasazi suddenly left the area.
然而，在13世纪末，阿纳萨齐人突然离开了该地区。
Experts do not know exactly why the Anasazi left.
专家们并不知道阿纳萨齐人离开的确切原因。
They think it was because there was no longer enough water to farm.
他们认为这是因为不再 drawings 有足够的水来务农。
And Meko's tree rings clearly show a serious drought at that time.
而梅科的树木年轮清楚地显示了当时的一场严重干旱。
How long will the current drought last?
当前的干旱会持续多久？
Using nature's clues from the past, experts predict that this drought may continue for another 50 years.
利用来自过去的自然线索，专家们预测这场干旱可能会再持续50年。
全英文全文 (Full English Text)
Dave Meko, a scientist at the University of Arizona, noticed that from 1999 to the following years, it became drier and drier. And water levels in the huge Colorado River were dropping rapidly. This was the beginning of a serious drought. Everyone began asking, "How long will it last?" Meko believed that he could find the answer in the trees.
Meko is a tree-ring expert. He studies the rings within a tree to find information about climate change. Each year, a tree adds a new layer of wood. These layers look like a series of rings. During times of heavy rainfall, the ring is wide. When there is a shortage of water, the ring is narrow. These rings are nature's record of rainfall and climate change.
Meko and his team quickly started a new research project. Their goal was to find out how long previous droughts lasted. The team collected as many old wood samples as possible. They tested wood samples from 1,200 years ago until the present. When they examined the rings, the news about rainfall in the past was not good.
Meko's research showed that the 20th century was an unusually wet time. Trees from this period had wide, healthy rings. Rain was plentiful during that century and millions of people moved to the region. Before that time, however, the rings showed that droughts occurred on a regular basis. In fact, drought was part of the usual climate pattern. There were serious droughts in the 900s, the 1100s and the late 1200s.
Human history seems to support Meko's findings. The native Anasazi lived in this area for hundreds of years, starting around 500 AD. They were farmers and depended on water to grow their crops. However, at the end of the 13th century, the Anasazi suddenly left the area. Experts do not know exactly why the Anasazi left. They think it was because there was no longer enough water to farm. And Meko's tree rings clearly show a serious drought at that time.
How long will the current drought last? Using nature's clues from the past, experts predict that this drought may continue for another 50 years.