VOA标准英语2014--Drylands Vulnerable to Climate Change

 

Drylands Vulnerable to Climate Change

Researchers warn that the world’s drylands are being severely¹ affected² by climate change. They say that could harm the livelihoods⁴ and food security for billions of people.

Scientists describe the projected effects of climate change on drylands as alarming. Dr. Jan Ruppert is among those raising concerns.

“Drylands cover a rather big amount of the terrestrial land surface with 40-percent – a little bit more even. And they are home to approximately two-point-five-billion people of which, more or less, one-billion directly live upon rangelands or upon very basic ecosystem⁵ services, such as fodder⁶ to herd⁷ animals. They are very important for a huge amount of people,” he said.

Ruppert is a rangeland ecologist at the University of Cologne. He conducted the research with his university colleague Dr. Anja Linstadter, who led the working group.

“Drylands are not particularly deserts. Deserts are part of drylands, but not all drylands are deserts. The main definition of drylands is that they have a scarcity⁸ of water obviously. The transpiration⁹ of the water from the soil is higher than the water that comes into the system by precipitation. Actually, if you think of a savannah – that will also be a dryland in most cases,” said Ruppert.

He said that drylands historically have fared pretty well during and after droughts. But they’re more at risk now due to the effects of climate change. Human activity, such as raising livestock¹⁰, can add environmental stress.

“Due to climate change the system is getting even more variable. So, the droughts will be more regular and droughts might be even more severe. And this can trigger or can push the systems above a certain tipping point and could lead to degradation¹¹. That means a change in the vegetation that cannot not be easily recovered from anymore,” he said.

Very severe droughts that usually occur only once every 100 years, may now occur much more often.

“The systems not only suffer during a drought, but also need some time to recover after a drought to be fully¹² functional¹³ again or to be on the same production level as they had been before the drought. And now, if you can imagine, that these droughts and even these very severe droughts – centennial-scale droughts – come in more often. Then we can expect gradual losses from the systems. The systems will not be as reliable as they have been before,” he said.

A centennial-scale drought can greatly reduce the production of plant biomass from 45 to more than 70-percent in some cases. Biomass is material from living and recently living plants.

Ruppert said, “We should also consider how these numbers have been calculated and that they only represent single year drought events. And usually a drought is a multi-year phenomenon. So these numbers are actually even more likely to underestimate the reduction in production because these effects from one year to another year – if you have a multi-year drought – might even add up and lead to even more pronounced losses.”

Some drylands could gradually turn to desert – a process called desertification.

The rangeland ecologist says the type of plants on drylands matters. For instance, drylands with mostly annual plants -- which complete their lifecycle within one year -- are more severely affected during droughts. But they recover more quickly afterwards.

It’s just the opposite when perennial¹⁴ plants – those that come back year after year -- are in the majority. Drylands are less severely affected during droughts, but recover more slowly. Drylands are also more resistant¹⁵ to animal grazing during droughts when annual plants dominate.

Ruppert said that eliminating grazing is not the answer to protecting drylands during droughts and during their recovery. Instead, he says there should be better grazing management – limiting the number of livestock on the land. Also, paying herders higher prices for a time would prevent them from increasing their livestock after a drought.

The University of Cologne rangeland ecologist said protecting drylands is a food security and a livelihood³ issue. However, he says it does not get the attention it deserves at climate conferences. The next conference – COP 20 – opens in Lima, Peru December 1st.

1 severely   

adv.严格地；严厉地；非常恶劣地

参考例句：

• He was severely criticized and removed from his post.他受到了严厉的批评并且被撤了职。
• He is severely put down for his careless work.他因工作上的粗心大意而受到了严厉的批评。

2 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

3 livelihood   

n.生计，谋生之道

参考例句：

• Appropriate arrangements will be made for their work and livelihood.他们的工作和生活会得到妥善安排。
• My father gained a bare livelihood of family by his own hands.父亲靠自己的双手勉强维持家计。

4 livelihoods   

生计，谋生之道( livelihood的名词复数 )

参考例句：

• First came the earliest individualistic pioneers who depended on hunting and fishing for their livelihoods. 走在最前面的是早期的个人主义先驱者，他们靠狩猎捕鱼为生。 来自英汉非文学 - 政府文件
• With little influence over policies, their traditional livelihoods are threatened. 因为马赛族人对政策的影响力太小，他们的传统生计受到了威胁。

5 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。

6 fodder   

n.草料；炮灰

参考例句：

• Grass mowed and cured for use as fodder.割下来晒干用作饲料的草。
• Guaranteed salt intake, no matter which normal fodder.不管是那一种正常的草料，保证盐的摄取。

7 herd   

n.兽群，牧群；vt.使集中，把…赶在一起

参考例句：

• She drove the herd of cattle through the wilderness.她赶着牛群穿过荒野。
• He had no opinions of his own but simply follow the herd.他从无主见，只是人云亦云。

8 scarcity   

n.缺乏，不足，萧条

参考例句：

• The scarcity of skilled workers is worrying the government.熟练工人的缺乏困扰着政府。
• The scarcity of fruit was caused by the drought.水果供不应求是由于干旱造成的。

9 transpiration   

n.蒸发

参考例句：

• These analyses depend on a number of potentially confounding factors such as nonstomatal transpiration and temperature. 这些分析取决于非气孔蒸腾和温度这样一些可能混淆的因素。
• Loss of water also includes the transpiration of water to the atmosphere from plants. 水的散失也包括从植物体中蒸腾到大气层中的水。

10 livestock   

n.家畜，牲畜

参考例句：

• Both men and livestock are flourishing.人畜两旺。
• The heavy rains and flooding killed scores of livestock.暴雨和大水淹死了许多牲口。

11 degradation   

n.降级；低落；退化；陵削；降解；衰变

参考例句：

• There are serious problems of land degradation in some arid zones.在一些干旱地带存在严重的土地退化问题。
• Gambling is always coupled with degradation.赌博总是与堕落相联系。

12 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

13 functional   

adj.为实用而设计的，具备功能的，起作用的

参考例句：

• The telephone was out of order,but is functional now.电话刚才坏了，但现在可以用了。
• The furniture is not fancy,just functional.这些家具不是摆着好看的，只是为了实用。

14 perennial   

adj.终年的；长久的

参考例句：

• I wonder at her perennial youthfulness.我对她青春常驻感到惊讶。
• There's a perennial shortage of teachers with science qualifications.有理科教学资格的老师一直都很短缺。

15 resistant   

adj.(to)抵抗的，有抵抗力的

参考例句：

• Many pests are resistant to the insecticide.许多害虫对这种杀虫剂有抵抗力。
• They imposed their government by force on the resistant population.他们以武力把自己的统治强加在持反抗态度的人民头上。