来自世界不同地方的六位学生在美国相遇。他们都是交换学生，到美国大学就读一个学期，学习英语，了解美国文化，同时修专业课程。英语“日常会话” (Everyday Conversations)系列围绕这六位学生在美国的经历展开。这套材料适于中级或中级以上英语水平的学生使用。

在这个对话中，一个学生（Lee）与两个同学（Jana和Akinyi）谈到北极和全球变暖。

Akinyi: The weather is getting so cold. I really hate it!

Jana: I do too. I miss the fall already. September was really lovely here. I wish we could have that weather all year.

Lee: Don’t say that. I don’t want the Earth to get any warmer. One of my classes yesterday got me freaked out about global warming.

Jana: More freaked out than usual?

Akinyi: I think we’re all concerned about global warming. What was different about yesterday’s class?

Lee: We started studying the melting permafrost in the Arctic.

Akinyi: The Earth has to get a lot warmer for the permafrost to melt, right?

Lee: No, and the scariest part is the feedback loop.

Jana: The feedback loop? What’s that?

Lee: Well, there’s carbon frozen in the permafrost, right? And when the permafrost melts, microbes release carbon dioxide and methane. This leads to more climate change.

Akinyi: What’s the loop part?

Lee: We all know that carbon dioxide and methane cause global temperatures to rise.

Jana: And if the temperature rises, then more permafrost melts.

Lee: Exactly. And when more permafrost melts, more carbon dioxide and methane is released. That causes global temperatures to rise even more. And the cycle continues.

Akinyi: That is one scary cycle. What can we do to stop it?

Lee: Reduce our carbon dioxide emissions. For most people this means using less energy, using cleaner energy like solar and wind, and driving less.

让我们来学习一些词语（也可阅读英文解释）：

Freak out：这个动词词组是一个非正式表达法，意思是变得担心、不安或害怕。

Global warming：全球变暖

Permafrost：永冻土

The Arctic ：北极地区

To melt：溶化

The feedback loop： 反馈循环，反馈圈。在这个对话中，它指的是地球温度升高造成永冻土溶化，导致二氧化碳和甲烷被释放到空中，进而使地球温度进一步升高，由此带来更多永冻土溶化，释放出更多的二氧化碳和甲烷。

Carbon：碳

Microbes：微生物

Carbon dioxide：二氧化碳

Methane：甲烷。这种气体吸热很快，会加剧地球变暖。

Reduce our carbon dioxide emissions：减少我们的二氧化碳排放

有兴趣听更多英语对话吗？请浏览“英语学习”专题网页。

American English 网站提供可供英语学生和教师免费使用的多种英语资源。American English Facebook网页提供每天更新的英语学习资料。

“日常会话”由美国国务院教育与文化事务局英语语言项目处（Office of English Language Programs, Bureau of Educational and Cultural Affairs）资深项目官员海蒂·豪兰（Heidi Howland）编写。

Everyday conversations: Talking about the weather [audio]

Six students from around the world meet. What do they have in common? They are all exchange students studying at a U.S. university for a semester. Throughout the semester, they learn more English, learn about U.S. culture, and learn more about their fields of study. This series of Everyday Conversations is about these six students and their experiences during a semester at a university in the U.S. These conversations are for intermediate-level English-language learners or higher.

In this conversation, a student (Lee) talks about the Arctic and global warming with two other students (Jana and Akinyi).

Akinyi: The weather is getting so cold. I really hate it!

Jana: I do too. I miss the fall already. September was really lovely here. I wish we could have that weather all year.

Lee: Don’t say that. I don’t want the Earth to get any warmer. One of my classes yesterday got me freaked out about global warming.

Jana: More freaked out than usual?

Akinyi: I think we’re all concerned about global warming. What was different about yesterday’s class?

Lee: We started studying the melting permafrost in the Arctic.

Akinyi: The Earth has to get a lot warmer for the permafrost to melt, right?

Lee: No, and the scariest part is the feedback loop.

Jana: The feedback loop? What’s that?

Lee: Well, there’s carbon frozen in the permafrost, right? And when the permafrost melts, microbes release carbon dioxide and methane. This leads to more climate change.

Akinyi: What’s the loop part?

Lee: We all know that carbon dioxide and methane cause global temperatures to rise.

Jana: And if the temperature rises, then more permafrost melts.

Lee: Exactly. And when more permafrost melts, more carbon dioxide and methane is released. That causes global temperatures to rise even more. And the cycle continues.

Akinyi: That is one scary cycle. What can we do to stop it?

Lee: Reduce our carbon dioxide emissions. For most people this means using less energy, using cleaner energy like solar and wind, and driving less.

Now let’s review the vocabulary.

Freak out is a phrasal verb and informal. It means to become anxious, upset or afraid.

Global warming: the increase in the Earth’s temperature caused by the increase of certain gases in the atmosphere, such as carbon dioxide.

Permafrost is ground that stays frozen for two or more years in a row.

The Arctic is the area around the North Pole.

To melt means to change from solid form to liquid form because of heat.

The feedback loop in this conversation refers to a cycle that keeps repeating and increasing. The warmer temperatures of the Earth cause permafrost to melt. When the permafrost melts, carbon dioxide and methane are released into the air. Carbon dioxide and methane cause global temperatures to increase even more. This causes more permafrost to melt and then more carbon dioxide and methane are released into the air.

Carbon is a chemical element.

Microbes are very tiny living things that can only be seen under a microscope (a special device used to clearly see tiny objects).

Carbon dioxide is a gas that is produced when people and animals breathe out. Carbon dioxide is also produced when certain fuels are burned. In this conversation, tiny organisms that are frozen in the permafrost release carbon dioxide when the permafrost melts. Increased carbon dioxide in the air can cause the earth’s temperature to increase.

Methane: a gas that can be burned for fuel. Methane absorbs (takes in) heat very quickly and can contribute to global warming.

Ready to learn more English? Our materials can help.

The American English website offers a variety of free resources for learners and teachers of English. The American English Facebook page posts learning materials for English-language learners daily.

Everyday Conversations are developed by the State Department’s Heidi Howland, a senior program officer in the Office of English Language Programs, Bureau of Educational and Cultural Affairs.