VOA标准英语2011--Climate Change Blamed for Dying African Trees

Climate Change Blamed for Dying African Trees

 

A lot of trees are dying in Africa’s Sahel region and new study says climate change caused by humans is to blame. What’s more, many tree species are also disappearing.

The study appears in the Journal of Arid¹ Environments. Climate change scientist Patrick Gonzalez led the research on six countries. At the time of the study, Gonzalez was a visiting scholar at the Center for Forestry² at the University of California at Berkeley.

“We conducted our research in the African Sahel, an arid region on the edge of the Sahara where people depend on trees for survival. And the Sahel has experienced the most severe drought in the world in the modern rainfall measurement record,” he said.

Drying up

The research shows that during the 20th Century rainfall in the Sahel dropped between 20 and 30 percent.

“One in six trees died in the last half of the 20th Century and, second, one in five tree species disappeared locally. And then third, together these changes shifted vegetation zones southward toward areas of more rainfall,” he said.

Rainfall in the African Sahel declined more than anywhere else in the world in the period of recorded measurements, causing increased aridity3, as evidenced by this dust storm in Senegal.

Possible causes of the vegetation shift include declining rainfall, growing human population and decreasing soil fertility.

“Our statistical⁴ comparison showed that climate outweighed⁵ the other factors. So, climate change was the main cause of the loss of the trees. Closer to the Sahara you have arid zone trees like Acacia with thorns. Very dry trees. And then as you move farther south towards the Equator, you have species that have fruits and hardwood and species that require more rainfall, that require moister conditions,” he said.

The study blames the climate change in the Sahel on motor vehicle and power plant emissions⁶ and other human activity over the years.

Gonzalez described conditions near the Sahara as long-term land degradation⁷.

“So we actually are showing a form of desertification. Desertification is land degradation. We’re not showing a shift of the sands of the Sahara, but what we are showing is a degradation far south of the Sahara within the Sahel within the Sudan, within Guinea. Those are the zones south of the Sahara,” he said.

Adapting, averting⁹

Local populations in the region have roots going back more than a thousand years and relocating is not an option. Indigenous¹⁰ people are adapting to climate change, for example, by caring for and pruning¹¹ small trees until they're mature. Such a practice can help double tree density¹² in a field.

However, Gonzalez said local populations cannot address climate change by themselves. He says the international community must act.

“The Intergovernmental Panel on Climate Change – that’s the top scientific panel that examines climate change and I sit on that panel – has shown that we, in the United States, and other industrialized nations have it in our power using current technologies and practices to avert⁸ more drastic impacts around the world by reducing our greenhouse gas emissions,” he said.

Gonzalez was joined in the research by Compton Tucker, senior earth scientist at NASA’s Goddard Space Flight Center and Hamady Sy, Mauritania’s country representative at the Famine Early Warning Systems Network. Both NASA and the U.S. Geological Survey provided funding for the study.

1 arid   

adj.干旱的；(土地)贫瘠的

参考例句：

• These trees will shield off arid winds and protect the fields.这些树能挡住旱风,保护农田。
• 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。

2 forestry   

n.森林学；林业

参考例句：

• At present, the Chinese forestry is being at a significant transforming period. 当前, 我国的林业正处于一个重大的转折时期。
• Anhua is one of the key forestry counties in Hunan province. 安化县是湖南省重点林区县之一。

3 aridity   

n.干旱，乏味；干燥性；荒芜

参考例句：

• The name Sahara conjures up images of a desert of aridity. "撒哈拉"这个名字使人想起干旱的沙漠情景。 来自辞典例句
• The name conjures up images of a desert of aridity. “撒哈拉”这个名字使人想起“干旱”的沙漠情景。 来自互联网

4 statistical   

adj.统计的，统计学的

参考例句：

• He showed the price fluctuations in a statistical table.他用统计表显示价格的波动。
• They're making detailed statistical analysis.他们正在做具体的统计分析。

5 outweighed   

v.在重量上超过( outweigh的过去式和过去分词 )；在重要性或价值方面超过

参考例句：

• This boxer outweighed by his opponent 20 pounds. 这个拳击选手体重比他的对手重20磅。 来自《简明英汉词典》
• She outweighed me by ten pounds, and sometimes she knocked me down. 她的体重超过我十磅，有时竟把我撞倒。 来自百科语句

6 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。

7 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。

8 avert   

v.防止，避免；转移(目光、注意力等)

参考例句：

• He managed to avert suspicion.他设法避嫌。
• I would do what I could to avert it.我会尽力去避免发生这种情况。

9 averting   

防止，避免( avert的现在分词 )； 转移

参考例句：

• The margin of time for averting crisis was melting away. 可以用来消弥这一危机的些许时光正在逝去。
• These results underscore the value of rescue medications in averting psychotic relapse. 这些结果显示了救护性治疗对避免精神病复发的价值。

10 indigenous   

adj.土产的，土生土长的，本地的

参考例句：

• Each country has its own indigenous cultural tradition.每个国家都有自己本土的文化传统。
• Indians were the indigenous inhabitants of America.印第安人是美洲的土著居民。

11 pruning   

n.修枝，剪枝，修剪v.修剪（树木等）( prune的现在分词 )；精简某事物，除去某事物多余的部分

参考例句：

• In writing an essay one must do a lot of pruning. 写文章要下一番剪裁的工夫。 来自《现代汉英综合大词典》
• A sapling needs pruning, a child discipline. 小树要砍，小孩要管。 来自《现代汉英综合大词典》

12 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。