2.5: Earth Takes a Breath
How do carbon dioxide (CO2) records at the poles of Earth reflect the carbon cycle in the biosphere?
In this unit, you have really engaged in the carbon cycle. After the aquarium experiment (Lesson 2.2), you are now thinking about carbon moving in systems around Earth. That's global thinking!
You have looked at sources and sinks of carbon on land and in the oceans. Photosynthesis and respiration move that carbon among reservoirs continually. Moreover, several factors either increased or decreased the rate of these processes.
In this lesson, you get to show what you have learned about carbon cycling. You have studied some records of CO2 in the atmosphere, such as at Mauna Loa. What do the data look like at other latitudes, such as at the poles? To do this, you will investigate data from the South Pole and very near the North Pole. You will learn:
Remember to use the focus question to guide your learning in this lesson.
Before you start your activity, review some ideas you have learned in Unit 2.
In Lesson 2.2, a high school class made measurements in an aquarium with aquatic plants. These connected to rates of photosynthesis and respiration depending on whether it was day or night. During photosynthesis, carbon dioxide is taken in and oxygen is released. Recall the reaction:
6CO2 + 6H2O + Energy → C6H12O6 + 6O2
During respiration, the reverse is true:
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy for the organism
Get with a partner to answer the questions below. You will compare CO2 data in two graphs. One graph represents carbon dioxide (CO2) in the water for an aquarium that contains an aquatic plant. It is by a window. The other is for CO2 levels in air at Mauna Loa. This is a good way to show your understanding of how carbon cycling acts at very different sizes.
You are part of the carbon cycle in several ways. One way is by using electrical energy. Answer the following questions about how carbon released by humans becomes part of the biosphere.
You have taken some field trips in Carbon Connections. This is fun, as you might not ever visit some of these places. The introduction to this lesson talked about going to the poles. This helps you understand the carbon cycle at different places on Earth. Let's travel to one now—Point Barrow, Alaska!
Point Barrow is the northernmost point in the United States. It lies on a point of land protruding out into the Arctic Ocean. It is above the Arctic Circle, so in the middle of winter it is dark for 24 hours; in summer, it is light for 24 hours.
Like Mauna Loa, Point Barrow has a climate station. It regularly measures CO2 levels of the air. These are reported as monthly averages. The ecosystem, or biome, at Point Barrow is Arctic tundra, yet the air arriving to the station has had a long journey around the Arctic. Before arriving at Point Barrow, much of the air has been interacting with boreal forests and tundra in northern Europe and Siberia (see map).
Examine with a partner the CO2 record from Point Barrow in the steps below. The most recent data extends to the start of 2008.
Don't put your coat away! For second field trip, you are going to the South Pole.
The South Pole is at the center of the continent of Antarctica. Most of Antarctica is covered by an ice sheet nearly two miles thick at some locations. Rugged mountains extend high above the ice sheet in spots, giving clues to Antarctic's geologic past. Some of these rocks contain dinosaur bones, indicating that Antarctica was not always so cold.
You saw an ice core record from Antarctica in Unit 1. Another important record of Antarctica's climate comes from a climate station on top of the ice at the South Pole. Most of Antarctica is surrounded by ocean (map). Winds circling Antarctica mix air that is interacting with the oceans and land. Both the land and ocean have seasons when productivity is high, and when it is low. That air also arrives at the climate station at the South Pole.
Investigate part of the CO2 record from the South Pole in the steps below. The most recent data extends to the start of 2006, so you will look again at a six-year period (2000-2006).
By looking at a selection of CO2 data from air in Unit 2, you started to see patterns and trends. These patterns and trends are related to interactions among parts of the carbon cycle in Earth's system. Having distinct patterns and trends offer scientists something else when working to understand the carbon cycle and climate. The patterns help them develop models of the systems. With those models, scientists can test explanations for how carbon cycles.
Listen to your teacher for when you will start Unit 3 of Carbon Connections. In that unit, you will get to try your hand at a climate model with several factors. Several of those factors relate to the carbon cycle. Using the model, you will get to investigate why that is!