Carbon In the Atmosphere

Part B: CO2My Life's Story

The carbon cycle has changed over Earth's history

Imagine if fossils didn't exist. How would we know that dinosaurs, woolly mammoths and other long-extinct creatures once roamed the Earth and swam in our oceans. Like fossils, carbon dioxide has left its own set of "clues" about past atmospheres and climates in ice cores a core sample that is typically removed from an ice sheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere. from Antarctica.

Take several minutes to examine the graph pictured above and then answer the Checking In questions below. The carbon dioxide data (blue lines) and temperature data (red lines) are taken from ice cores drilled in Vostok Station Antarctica. The peaks of carbon dioxide indicate interglacialwarm period within a glacial age periods and the troughs represent ice ages any geological period in which long-term cooling takes place and ice sheets and glaciers exist. (also called glacial ages).

Checking In

Answer the following questions based on the graph above:
  1. Which of the following best describes the temperature pattern?
    [INCORRECT]
    [INCORRECT]
    [INCORRECT]
    [CORRECT]
  2. Which of the following best describes the CO2 pattern?
    [CORRECT]
    [INCORRECT]
    [CORRECT]
    [INCORRECT]
  3. From 600,000 years ago to 100,000 years ago, what was the highest concentration of carbon dioxide(ppm)
    [INCORRECT]
    [INCORRECT]
    [CORRECT]
    [INCORRECT]
  4. The carbon cycle can change on vastly different time scales. CO2 data from the Vostok ice cores provides evidence for the carbon cycle fluctuating between ice ages on a time scale of approximately ______?
    [INCORRECT]
    [INCORRECT]
    [INCORRECT]
    [INCORRECT]
    [CORRECT]
  5. How much of a global temperature change occurred as ice ages gradually changed to interglacial periods and back again?
    [INCORRECT]
    [INCORRECT]
    [CORRECT]
    [INCORRECT]

Discuss

The ice core CO2 and temperature data you just explored raises some interesting, more complex questions. Read the questions below and be prepared to discuss them after watching the movie below. Take notes, pausing and replaying as needed. NOTE: Your teacher may decide to assign each group specific questions to take notes on.
  • How are ice ages and interglacial periods related to carbon dioxide and temperature? Why are ice cores critical to revealing this relationship?
  • What causes ice ages to come and go?
  • Does ice core data measured at Vostok reflect historic temperatures and concentrations of atm CO2on a regional scale or a global scale. What is the evidence? Why is knowing the spatial scale important?
  • How were changes in CO2 and temperature related to each other as Earth swung back and forth between ice ages and interglacial periods? For example, which came first- a rise in temperature or a rise in CO2?
  • Were there any feedbacks operating as temperature and concentrations of CO2 changed? If so, how did they operate and at what time scale?


To help you answer these important questions, focus on the following topics as you watch the video:
  • Temperature data from ice cores from Vostok and Epica in Anarctica and ice volume changes from ocean sediment cores.layers of ocean sediments that contain shells and fossils of marine organisms that died long ago, dust and other materials; varieties and concentration of certain fossil microorganisms record past changes in ocean temperature and composition; collected by scientists to reconstruct past paleoclimates
  • Milaknovitch cycles and ice ages
  • The relationship between changes in temperature, CO2, water vapor (H2O) evaporated from ocean.
  • NOTE: If the video does not load, you can watch it at this link: Mother Nature's History Book from the Pacific Institute for Climate Solutions


    Stop and Think

    1: Describe the relationship between carbon dioxide, temperature and ice ages.


    A slow acting geologic carbon cycle is key to reducing the concentration of atm CO2 over very long time scales (hundred thousands of years to millions of years).


    As Earth swung between ice ages and interglacial periods over the past 800,000 years, the concentration of atm CO2 rose and fell with these swings. A slow-acting geological carbon cycle is responsible for reducing the concentration of atm CO2as Earth swung from interglacial periods to ice ages. Atmospheric chemistry, rain, and rock weathering worked in concert to slowly remove CO2 from the atmosphere over long time scales of hundreds of thousands of years. Watch and listen to Harvard University professor Dr. Daniel Schrag explain to high school students why the processes of Earth's geological carbon cycle is critical to the stability of Earth's climate over long time scales. As you watch the video, take notes on the following:

    https://www.youtube.com/watch?v=AroXldQiXEA&feature=youtu.be


    NOTE: If the video does not load, you can watch it at HHMI: The Geological Carbon Cycle

    Checking In

    1: Explain how the geological carbon cycle is critical to the stability of Earth's climate over very long timescales.

    2: Explain how the Biosphere and Geopshere work together in the geological carbon cycle to create a long term carbon sink of millions of years.

    Optional extensions

    Want to learn more about ice cores, sediment cores, Milankovitch cycles, and changes in CO2over Earth's history? Check out these resources: