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.