Lesson 9

How can we figure out what is "normal"?

We can go to the Antarctic! Each year, scientists travel to the ice sheets of Antarctica to see what they can learn from gas bubbles trapped in ice. Antartica is the perfect place to study carbon dioxide levels. The ice sheets are home to few animals and occasionally humans. This means any gas bubbles trapped in ice are there from the atmosphere.

To study carbon dioxide levels, scientists spend up to three months living on the ice sheet. They sleep in special tents that are designed for cold temperatures (pictured below). They eat in wood structures that they temporarily build just for the time they are there. They have to shovel and melt snow for drinking water, for showering, and for doing laundry.

They have to deal with harsh conditions, but their work is very important for understanding if changes in the amount of carbon dioxide in the atmosphere are part of normal cycles that Earth goes through.

Would you want to travel there as part of a science team? Why or why not?

How do the gas bubbles get into the ice?

Teams of scientists go to Antarctic ice sheets that are up to two miles thick. Thick ice sheets can contain gas bubbles that are many years old. Layers of ice form on top of older layers of ice. The deeper you go, the older the ice. Dr. Peter Neff is one of the scientists studying gas bubbles in ancient ice. Take a look at the video to hear how the ice bubbles get trapped deep in the ice sheet.

Is this similar or different from what you observed in the ice cubes made from tap water?

What do you think ancient ice cubes would taste like?

How do scientists get the ancient ice?

Imagine standing on a sheet of ice that is two miles thick. The ice you want is thousands of feet below the surface. How do you get to it? Once you have it, how do you use it to study carbon dioxide levels in the atmosphere?

First, you use a special drill that cuts "ice cores" that are a few meters long. Depending on how old the ice needs to be, it may take several days or even weeks to go deep enough into the ice sheet.

Once you have the ice you need, you have to get the gas bubbles out. When you looked at the carbonated ice, how did you get the bubbles out? You melted it! That's exactly what the scientists do. They have special equipment that traps the air as the ice cores melt. Then, special sensors tell them how much carbon dioxide was trapped in each layer of ice.

Watch the short video on the right to learn more about how scientists study ice core data. As you watch, think about what the scientists are doing. How is their process similar or different from what you did in class with the ice cubes and the carbon dioxide detector?