SSS 2009-07-01
时间：2019-01-08 作者：英语课 分类：Scientific American(七)月
This is Scientific American's 60-Second Science, I'm Christie Nicholson. Got a minute?
During the last ice age our problem was too little carbon. Unlike today where too much carbon is causing global warming. Past glacial ages occurred partly because the weathering of rocks, over millions of years, pulls CO2 from the atmosphere, locking it in ocean floor sediment 1. The rise of global mountain ranges during the last 25 million years should have sucked all the CO2 from atmosphere sending the Earth to an icy death. But that never happened. CO2 levels stabilized 2 at about 250 parts per million. This week in the journal Nature, researchers announce one reason why this happened: plants. Leafy greens need CO2 to live, and when CO2 levels drop significantly they starve. Researchers say that the plant numbers decreased to a level where volcanoes and other carbon-creating sources produced CO2 faster than the remaining plants could remove it. So the Earth remained somewhat warm. It may seem that our leafy friends could help us now, this time from overheating. But ultimately 3 we’re producing too much CO2 too fast for natural weathering processes to remove it. Ultimately, we need a way to stop producing CO2 in the first place.
Thanks for the minute for Scientific American's 60-Sceond Science. I'm Christie Nicholson.
- The sediment settled and the water was clear.杂质沉淀后，水变清了。
- Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。
- The patient's condition stabilized. 患者的病情稳定下来。
- His blood pressure has stabilized. 他的血压已经稳定下来了。 来自《现代英汉综合大词典》
- It was a demeaning and ultimately frustrating experience.那是一次有失颜面并且令人沮丧至极的经历。
- Vitamin C deficiency can ultimately lead to scurvy.缺乏维生素C最终能道致坏血病。