美国国家公共电台 NPR--研究发现:美国西部特大干旱,是1200年以来最严重的一次

Study finds Western megadrought is the worst in 1,200 years

Transcript¹

Shrunk reservoirs. Depleted² aquifers³. Low rivers. Raging wildfires. It's no secret that the Western U.S. is in a severe drought. New research published Monday shows just how extreme the situation has become.

The Western U.S. and northern Mexico are experiencing their driest period in at least 1,200 years, according to the new study, published in the journal Nature Climate Change. The last comparable — though not as severe — multidecade megadrought occurred in the 1500s, when the West was still largely inhabited by Native American tribes.

Today, the region is home to tens of millions of people, massive agricultural centers and some of the fastest-growing cities in the U.S. — all in an area where there's less water available than there was in the past, partially⁴ due to human-caused climate change.

"We have a society that's relying on there being the amount of water there was in the 1900s," said the study's lead author, Park Williams, a bioclimatologist at the University of California, Los Angeles. "But now with the number of water molecules⁵ available to us declining, it really is time for us to get real about how much water there is for us to use."

Williams looked at tree ring data from thousands of sites to conduct the research. The researchers sampled data collected from live trees, dead trees and wood beams preserved at Native American archeological sites. The tree rings gave Williams insight into drought events dating back to A.D. 800, around the time Charlemagne was being crowned emperor of Rome.

He identified four other megadroughts in that time period, the most notable being a 23-year drought that ended in the late 1500s. There were hopes during a wet 2019 that the current megadrought was following a similar pattern, Williams said.

"And then from summer 2020 through all of 2021, it was just exceptionally dry across the West ... indicating that this drought is nowhere near done."

It's time to "pull out all the stops" and plan for less water

Western water managers were again hopeful for a change at the beginning of this winter. In December, California's Sierra Nevada had record-breaking snowfall, and big snowstorms blanketed the northern Rockies. But a hot, dry start to the year has since dropped snowpack levels to below average in many places.

Lake Mead⁶ and Lake Powell, the country's two largest reservoirs, are filled at only about one-third of their total capacity. Communities, ranchers and farmers have depleted groundwater stores to meet demands.

Federal water managers declared the first-ever water shortage along the Colorado River last year, triggering cuts to some of the river's 40 million users. It was a recognition "that the hydrology that was planned for years ago — but we hoped we would never see — is here," said Bureau of Reclamation⁷ Commissioner⁸ Camille Touton.

"The Colorado River Basin no longer has the privilege of time," said Kim Mitchell, senior water policy adviser⁹ at Western Resource Advocates, an environmental nonprofit, after hearing about the new research. "It's imperative¹⁰ for water managers in the West to incorporate a smaller [Colorado] River into future operations and pull out all the stops in scaling up basin-wide conservation. Incremental¹¹ solutions just won't be enough."

Human-caused climate change contributes to drought

Existing management guidelines for the Colorado River are set to expire in 2026. The seven states that draw from the watershed¹² are negotiating with the federal government, Native American tribes and Mexico over what future management should look like.

Last December, Nevada, Arizona and California agreed to take less water from the Colorado River in an effort to prop¹³ up Lake Mead, and more cuts could follow.

"This is a wake-up call for everyone," Adel Hagekhalil, general water manager for the Metropolitan¹⁴ Water District of Southern California, told KUNC. "For all of us. We are facing a new normal when it comes to climate change."

Williams, the study author, said roughly one-fifth of the current megadrought can be attributed to human-caused climate change. Greenhouse gas emissions¹⁵ are warming the world, speeding evaporation¹⁶ and disrupting weather patterns.

He described water patterns in the West as a yo-yo — sometimes high, sometimes low. Climate change has put that yo-yo on an escalator heading down, he said, "and we cannot let ourselves get tricked by a few wet years into giving up on the progress we've been making."

"We actually have to change our relationship with water."

1 transcript   

n.抄本，誊本，副本，肄业证书

参考例句：

• A transcript of the tapes was presented as evidence in court.一份录音带的文字本作为证据被呈交法庭。
• They wouldn't let me have a transcript of the interview.他们拒绝给我一份采访的文字整理稿。

2 depleted   

adj. 枯竭的, 废弃的 动词deplete的过去式和过去分词

参考例句：

• Food supplies were severely depleted. 食物供应已严重不足。
• Both teams were severely depleted by injuries. 两个队都因队员受伤而实力大减。

3 aquifers   

n.地下蓄水层，砂石含水层( aquifer的名词复数 )

参考例句：

• And in Africa, the aquifers barely recharge at all. 非洲的地下水开采以后几乎得不到补充。 来自时文部分
• Aquifers have water contents over 30%. 含水层的水含过30％。 来自辞典例句

4 partially   

adv.部分地，从某些方面讲

参考例句：

• The door was partially concealed by the drapes.门有一部分被门帘遮住了。
• The police managed to restore calm and the curfew was partially lifted.警方设法恢复了平静，宵禁部分解除。

5 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

6 mead   

n.蜂蜜酒

参考例句：

• He gave me a cup of mead.他给我倒了杯蜂蜜酒。
• He drank some mead at supper.晚饭时他喝了一些蜂蜜酒。

7 reclamation   

n.开垦；改造；（废料等的）回收

参考例句：

• We should encourage reclamation and recycling.我们应当鼓励废物的回收和利用。
• The area is needed for a land reclamation project.一个土地开垦项目要在这一地区进行。

8 commissioner   

n.（政府厅、局、处等部门）专员，长官，委员

参考例句：

• The commissioner has issued a warrant for her arrest.专员发出了对她的逮捕令。
• He was tapped for police commissioner.他被任命为警务处长。

9 adviser   

n.劝告者，顾问

参考例句：

• They employed me as an adviser.他们聘请我当顾问。
• Our department has engaged a foreign teacher as phonetic adviser.我们系已经聘请了一位外籍老师作为语音顾问。

10 imperative   

n.命令，需要；规则；祈使语气；adj.强制的；紧急的

参考例句：

• He always speaks in an imperative tone of voice.他老是用命令的口吻讲话。
• The events of the past few days make it imperative for her to act.过去这几天发生的事迫使她不得不立即行动。

11 incremental   

adj.增加的

参考例句：

• For logic devices, the incremental current gain is very important. 对于逻辑器件来说，提高电流增益是非常重要的。 来自辞典例句
• By using an incremental approach, the problems involving material or geometric nonlinearity have been solved. 借应用一种增量方法，已经解决了包括材料的或几何的非线性问题。 来自辞典例句

12 watershed   

n.转折点，分水岭，分界线

参考例句：

• Our marriage was at a watershed.我们的婚姻到了一个转折关头。
• It forms the watershed between the two rivers.它成了两条河流的分水岭。

13 prop   

vt.支撑；n.支柱，支撑物；支持者，靠山

参考例句：

• A worker put a prop against the wall of the tunnel to keep it from falling.一名工人用东西支撑住隧道壁好使它不会倒塌。
• The government does not intend to prop up declining industries.政府无意扶持不景气的企业。

14 metropolitan   

adj.大城市的，大都会的

参考例句：

• Metropolitan buildings become taller than ever.大城市的建筑变得比以前更高。
• Metropolitan residents are used to fast rhythm.大都市的居民习惯于快节奏。

15 emissions   

排放物( emission的名词复数 )； 散发物（尤指气体）

参考例句：

• Most scientists accept that climate change is linked to carbon emissions. 大多数科学家都相信气候变化与排放的含碳气体有关。
• Dangerous emissions radiate from plutonium. 危险的辐射物从钚放散出来。

16 evaporation   

n.蒸发，消失

参考例句：

• Be careful not to lose too much liquid by evaporation.小心不要因蒸发失去太多水分。
• Our bodies can sweat,thereby losing heat by evaporation.我们的身体能出汗，由此可以蒸发散热。