VOA慢速英语--飓风在波多黎各创造了自然气候变化实验室

Hurricanes Create Natural Climate Change Laboratories in Puerto Rico

The hurricanes that hit Puerto Rico in 2017 destroyed most of the island’s forest cover. The storms may have given scientists ideas about how the world will react to climate change and increasingly severe weather.

Puerto Rico’s El Yunque is the only tropical rain forest under the direction of the United States Forest Service. Researchers there are running controlled studies on how plants react to higher temperatures combined with severe weather, starting with Hurricane Maria.

Not far away, another group of researchers is looking at how hurricanes affect the forest environment.

Forest Service researcher Tana Wood leads a team testing how plants themselves react to higher temperatures. The 2017 hurricane season, with Maria following another storm -- Hurricane Irma, has given researchers a chance to see how storms affect the recovery of struggling ecosystems². This is a concern on Caribbean islands, where scientists say rising temperatures could lead to more intense storms.

On a recent trip to the Forest Service research center, Wood moved through thick plant life and plant leaves the size of laptop computers. She made her way to three areas surrounded by infrared³ panels⁴. The devices raise the air and soil temperature by about 4 degrees Celsius⁵.

The plants around the research center were shorter and had more of a brown color than the three unheated control areas. The warmed areas operate on 480 volts⁶ of electricity. The power lines are separated from the ground, but the scientists wear special footwear to avoid getting shocked in case of an accident.

Nearby, scientist Rob Tunison put what looked like a small mirror around a dark green plant leaf. He spent 30 minutes to an hour working on each leaf.

Wood said they are looking at how soils react and temperatures affect natural processes. One example is photosynthesis⁷, the process through which plants turn sunlight into energy while taking in carbon dioxide and releasing that gas and oxygen into the atmosphere.

The researchers are also studying nutrients⁸ and microorganisms in the warmed areas. They freeze some of the nutrients and organisms and send them to a laboratory in California for examination.

Knowledge about plants and soils in tropical areas could eventually be used in models to identify how larger ecosystems react to changes. Wood added that researchers are able to look at the possibility for tropical plants and soils to react to warmer conditions over time.

Tropical forests are important in recovering and reusing carbon dioxide, one of the gasses that studies have linked to slowly rising temperatures in Earth’s atmosphere. And such forests store about a third of the world’s carbon, Wood said. They also help produce rainfall across the world by releasing water vapor⁹, which in turn creates clouds.

“Anything that happens in these systems can have an effect on the world’s climate,” she said.

In February, U.S., British and international climate agencies reported that 2018 was the fourth-warmest year on record. Worldwide production of heat-trapping carbon dioxide saw its largest increase in seven years. In all, carbon dioxide emissions¹⁰ worldwide have increased 55 percent in the past 20 years. And the U.S. National Oceanic and Atmospheric¹¹ Administration reports that Earth has warmed on average about two-thirds of a degree Celsius.

British weather experts noted¹² in February that the world could set record-breaking temperatures over the next five years. Scientists expect the world will produce 37.1 billion metric tons of carbon dioxide this year. Studies from the Global Carbon Project show that is up from 36.2 billion metric tons produced in 2018.

Kim Cobb is a climate scientist at the Georgia Institute of Technology. She was not involved in the experiments at El Yunque. Cobb said she did not know of any other long-term warming experiments in tropical rainforests. And what will happen at the U.S. Forest Service’s site is unclear.

“It’s not a system that we can model extremely well today, let alone under climate change scenarios,” Cobb said. “But there is little doubt that these kinds of long-term monitoring sites are extremely valuable in ... our understanding of the water and carbon cycle, and how they might change with climate change.”

The $3 million project is now in its fourth year. Wood said she hopes it will continue as long as possible. Scientists halted the project for a year after Hurricane Maria hit Puerto Rico on September 20, 2017. That way they could separate the effect of warming from the effect of the storm, which caused more than $100 billion in damage.

Not far from Woods’ experiment, scientists are looking at how hurricanes affect the tropical forest. They began by cutting away the highest leaves above parts of the forest to recreate the effects of a storm. They paid workers to cut tree branches and spread them across the forest floor. That helped them study how light and water move through the changed ecosystem¹ and the effect that fallen trees have on soil microbes. They also are measuring cloud base heights to get a sense of how changes could affect rainfall.

Maria suddenly gave them a real-life test.

“It poses¹³ a lot of challenges but a lot of opportunities to move the science forward,” said Grizelle Gonzalez, a project leader.

The experiments are expected to continue for several years. That is unless new storms move into the Caribbean. Another Atlantic Ocean hurricane season starts June 1.

I’m Caty Weaver¹⁴.

And I’m Pete Musto.

Words in This Story

tropical – adj. of, relating to, occurring in, or used in the part of the world that is near the equator¹⁵ where the weather is very warm

ecosystem(s) – n. everything that exists in a particular environment

infrared panel(s) – n. a flat device that produces or uses rays of light that cannot be seen and that are longer than rays that produce red light

volt(s) – n. a unit for measuring the force of an electrical current

mirror – n. a piece of glass that reflects images

vapor – n. a substance that is in the form of a gas or that consists of very small drops or particles mixed with the air

emission(s) – n. the act of producing or sending out something such as energy or gas from a source

scenario(s) – n. a description of what could possibly happen

monitor(ing) – v. to watch, observe, listen to, or check something for a special purpose over a period of time

challenge(s) – n. a difficult task or problem

opportunities – n. an amount of time or a situation in which something can be done

1 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。

2 ecosystems   

n.生态系统( ecosystem的名词复数 )

参考例句：

• There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
• Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样，从雨林到半荒漠等不一而足。 来自辞典例句

3 infrared   

adj./n.红外线(的)

参考例句：

• Infrared is widely used in industry and medical science.红外线广泛应用于工业和医学科学。
• Infrared radiation has wavelengths longer than those of visible light.红外辐射的波长比可见光的波长长。

4 panels   

镶板( panel的名词复数 )； 面； （门、墙等上面的）嵌板； 控制板

参考例句：

• One of the glass panels in the front door was cracked. 前门的一块方玻璃破裂了。
• Make sure the panels are treated with a wood preservative. 确保镶板用木材防腐剂处理过。

5 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

6 volts   

n.（电压单位）伏特( volt的名词复数 )

参考例句：

• The floating potential, Vf is usually only a few volts below ground. 浮置电势Vf通常只低于接地电位几伏。 来自辞典例句
• If gamma particles are present, potential differences of several thousand volts can be generated. 如果存在γ粒子，可能产生几千伏的电位差。 来自辞典例句

7 photosynthesis   

n.光合作用

参考例句：

• In apple trees photosynthesis occurs almost exclusively in the leaves.苹果树的光合作用几乎只发生在叶内。
• Chloroplasts are the structures in which photosynthesis happens.叶绿体就是光合作用发生的地方。

8 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

9 vapor   

n.蒸汽，雾气

参考例句：

• The cold wind condenses vapor into rain.冷风使水蒸气凝结成雨。
• This new machine sometimes transpires a lot of hot vapor.这部机器有时排出大量的热气。

10 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。

11 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

12 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

13 poses   

使摆姿势( pose的第三人称单数 )； 以…身份出现； 招摇； 炫耀

参考例句：

• This poses a threat to agriculture and the food chain, and consequently to human health. 这会对农业和食物链造成威胁，由此而危及人的健康。
• The high cost of oil poses serious problems for industry. 昂贵的石油价格给工业造成了严重困难。

14 weaver   

n.织布工；编织者

参考例句：

• She was a fast weaver and the cloth was very good.她织布织得很快，而且布的质量很好。
• The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。

15 equator   

n.赤道，（平分球形物体的面的）圆

参考例句：

• Singapore is near the equator.新加坡位于赤道附近。
• The United States is north of the equator.美国位于赤道以北。