Lab 11.1

Lab 11.1 – From Fossil Fuels to the Ocean

Fundamental concept: Atmospheric CO2 is increasing over time due to human activity.
Estimated time to complete: 25 minutes
Data skills preparation: TBD
Materials needed: None

In this lab activity you will learn about atmospheric CO2 and its link to the ocean. We track long-term changes in atmospheric CO2 using the Keeling Curve, which represents CO2 concentrations measured in Mauna Loa in Hawaii. The Keeling Curve below highlights temporal patterns, or patterns across time, in CO2 concentrations at both long-term (across years) and short-term (within years) scales.

Carbon dioxide concentrations at Mauna Loa Observatory by NOAA is licensed under the Public Domain. Original Source.
Note: Due to the eruption of the Mauna Loa Volcano, measurements from Mauna Loa Observatory were suspended as of Nov. 29, 2022. Observations from December 2022 to July 4, 2023 are from a site at the Mauna Kea Observatories, approximately 21 miles north of the Mauna Loa Observatory. Mauna Loa observations resumed in July 2023.

Before answering the questions below, take a look at the curve and watch this video about how scientists measure atmospheric CO2.

Orientation Questions

1. What are the independent and dependent variables on the Keeling curve?
2. What range of CO2 concentrations do you see in the Keeling Curve?
3. What were the CO2 levels when Dr. Dave Keeling started taking his measurements of CO2 in the 1950s?
4. What graph type is this (hint: Look back at Lab 2)? Choose from below:
   1. Time Series
   2. Station Profile
   3. Bubble Chart
   4. Bathymetric Chart

Interpretation Questions

5. What temporal patterns are evident in this curve at long timescales (across many years)? What do you think is driving these patterns?
6. What temporal patterns are evident in this curve at short timescales (within a year)? What do you think is driving these patterns?

From Fossil Fuels to Ocean CO2

The ocean and atmosphere are coupled systems that are constantly exchanging dissolved gasses that are very important to living organisms, particularly oxygen (O2), carbon dioxide (CO2), and nitrogen (N2). The ocean absorbs about 30% of the CO2 that is released in the atmosphere. As levels of atmospheric CO2 increase from human activity such as burning fossil fuels (e.g., car emissions) and changing land use (e.g., deforestation), the amount of  CO2 absorbed by the ocean also increases. 

Application Question

7. If you were to create a Keeling curve for the ocean, how do you think it would compare to the curve shown for atmospheric CO2? 

1. The CO2 concentration in the ocean would not change at all over time
2. The CO2 concentration in the ocean would change faster than the atmospheric CO2 concentration 
3. The CO2 concentration in the ocean would change slower than the atmospheric CO2 concentration 
4. The CO2 concentration in the ocean would change at a similar rate to the atmospheric CO2 concentration 

Behind the Scientist

It was 1953, and Dave Keeling was a post-doctoral researcher in Pasadena, California. While Dave’s research focused on nuclear power, he became interested in carbonate chemistry and decided to go on a side quest: he started taking CO2 measurements under varying conditions – along industrialization gradients, at the tops of mountains and in temperate rainforests, during the night and during the day, and in different seasons. Dave never stopped taking these measurements and later that decade he received funding to install continuous CO2 monitors at Mauna Loa, Hawaii. The resulting dataset has become the longest-running time series of CO2 data in the world and has been integral to our understanding of the natural and anthropogenic drivers of CO2.