Earth and Sky:Forests and CO2 森林和二氧化碳

Forests and CO2 森林和二氧化碳

The amount of fossil fuel emissions¹ released into the atmosphere has steadily² risen since the Industrial Revolution. But recently, part of those emissions have been disappearing. Learn more about forests and CO2 -- on today's Earth and Sky.

DB: This is Earth and Sky. When we burn fossil fuels, we send carbon dioxide -- or CO2 -- into the air. Most scientists think this CO2 contributes to global warming. In the past 20 years, levels of CO2 in the atmosphere haven't risen as much as expected from the rate of our CO2 emissions. Researchers think forests are absorbing some of this extra CO2.

Steven Wofsy: They're doing us a very big favor. They're taking 25% of the fossil fuel CO2 and making it disappear from the atmosphere...

DB: Steven Wofsy researches atmospheric³ and environmental chemistry at Harvard University.

Steven Wofsy: So we'd very much like to understand why plants are doing this now -- they weren't doing it 20 years ago and what holds the future ... Perhaps plants will continue to take up CO2, perhaps they won't, perhaps what's been stored will actually come back into the atmosphere.

DB: Global warming has extended the growing season and the amount of CO2 that plants can absorb in a year. But Wofsy said that global warming could eventually damage forests by favoring pests. He's helping⁴ to design new satellite instruments to better measure how much CO2 is exchanged between forests, oceans and the air. For more, come to today's show at earthsky.org. Special thanks to the National Science Foundation -- where discoveries begin. I'm Deborah Byrd for Earth and Sky.

1 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。

2 steadily   

adv.稳定地；不变地；持续地

参考例句：

• The scope of man's use of natural resources will steadily grow.人类利用自然资源的广度将日益扩大。
• Our educational reform was steadily led onto the correct path.我们的教学改革慢慢上轨道了。

3 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。

4 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。