2007-10-02, Greenhouse Gases 温室效应

On a restricted site in northern Wisconsin, the hissing¹ you hear is helping² scientists see the future. Inside towering rings of pipes, aspen, birch, and sugar maples³ feed on measured diets of greenhouse gases.

Our studies were looking at what forest will be faced with in, in about 50 years from now.

Emissions⁴ from automobiles⁵ and industry are increasing carbon dioxide and ozone⁶ levels in the atmosphere, so government agencies and research institutions have become partners in the ASPEN FACE project (Free-Air, Carbon Dioxide Enrichment).

Their goal - to see how future forest will grow in higher levels of greenhouse gases. This is big science for us; there are very few places in the world where forestry⁷ can garner⁸ these sorts of resources for a huge experiment. Inside the gas-enriched rings, researchers constantly monitor the forest environment. (Alright, why don't we go back into the canopy⁹ a little bit?) For example, they measure the rate at which trees convert carbon dioxide to food. As long as the leaf is active, it's taking in carbon dioxide out of that air stream, and it's giving off water vapour.

Their research has led to some striking early discoveries. In rings where the trees are fed just elevated levels of carbon dioxide. It's a little like an all-you-can-eat buffet¹⁰. Well, as far as the plants are concerned, it's entirely¹¹ a good thing. It's just like having more food on the dinner table.

Trees need carbon dioxide to survive and here they get plenty. One of the things that we have noticed with elevated CO2, at least early on in the canopy development is that we have a thicker canopy, the leaves are a little larger. If trees can absorb much more CO2, that might reduce its impact on global warming.

What's more troubling to researchers, in the short term, is the effect they can see from another major greenhouse gas - ozone. With ozone, the responses are absolutely the opposite. They are mainly negative responses in terms of, of growth. We are seeing increased levels of mortality; we are seeing increased levels of insect and disease attack on these, with the injury both on the lower leave surface and upper leave surface. The first effect is the air pollution. It's all the biotic stuff that moves in after that. It's the sharks that smell blood in the water, so to speak, that, that causes real problems.

This ladybug may eat 5000 aphis in a life time, ladybugs don't thrive in ozone, plant-eating aphis do. Scientists don't know whether there is such a thing as too much carbon dioxide or safe level of ozone for trees. What they have now.

1 hissing   

n. 发嘶嘶声, 蔑视 动词hiss的现在分词形式

参考例句：

• The steam escaped with a loud hissing noise. 蒸汽大声地嘶嘶冒了出来。
• His ears were still hissing with the rustle of the leaves. 他耳朵里还听得萨萨萨的声音和屑索屑索的怪声。 来自汉英文学 - 春蚕

2 helping   

n.食物的一份&adj.帮助人的，辅助的

参考例句：

• The poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
• By doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。

3 maples   

槭树，枫树( maple的名词复数 )； 槭木

参考例句：

• There are many maples in the park. 公园里有好多枫树。
• The wind of the autumn colour the maples carmine . 秋风给枫林涂抹胭红。

4 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。

5 automobiles   

n.汽车( automobile的名词复数 )

参考例句：

• When automobiles become popular,the use of the horse and buggy passed away. 汽车普及后，就不再使用马和马车了。 来自《简明英汉词典》
• Automobiles speed in an endless stream along the boulevard. 宽阔的林荫道上，汽车川流不息。 来自《现代汉英综合大词典》

6 ozone   

n.臭氧，新鲜空气

参考例句：

• The ozone layer is a protective layer around the planet Earth.臭氧层是地球的保护层。
• The capacity of ozone can adjust according of requirement.臭氧的产量可根据需要或调节。

7 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。

8 garner   

v.收藏；取得

参考例句：

• He has garnered extensive support for his proposals.他的提议得到了广泛的支持。
• Squirrels garner nuts for the winter.松鼠为过冬储存松果。

9 canopy   

n.天篷，遮篷

参考例句：

• The trees formed a leafy canopy above their heads.树木在他们头顶上空形成了一个枝叶茂盛的遮篷。
• They lay down under a canopy of stars.他们躺在繁星点点的天幕下。

10 buffet   

n.自助餐；饮食柜台；餐台

参考例句：

• Are you having a sit-down meal or a buffet at the wedding?你想在婚礼中摆桌宴还是搞自助餐？
• Could you tell me what specialties you have for the buffet?你能告诉我你们的自助餐有什么特色菜吗？

11 entirely   

ad.全部地，完整地；完全地，彻底地

参考例句：

• The fire was entirely caused by their neglect of duty. 那场火灾完全是由于他们失职而引起的。
• His life was entirely given up to the educational work. 他的一生统统献给了教育工作。