# Investigation 1

## How Has the Concentration of Carbon Dioxide and Temperature Changed Over the Past 800,000 Years?

Take a look at the graph below. Does the data on the interactive graph look familiar? In the last module, you learned how temperatures changed over time by analyzing temperature data derived from Dome C ice cores in Antarctica. You examined temperature data over 800,000 years and saw a similar pattern of peaks (interglacial periods) and valleys (glacial periods). Not too far from Dome C is the Law Dome, which is named after Australian scientist and explorer, Philip Law. In this investigation, you will analyze CO2 data obtained from the Law Dome and compare it to 800,000 years of temperature data.

## CO2 Concentrations and Temperature Anomaly Readings Over the Past 800,000 Years

1. Look at the concentration of CO2 over the past 800,000 years and describe the general pattern that you see.
2. Calculate the estimated rate of change for three sequential periods of extreme low to high concentrations of CO2. To do this, zoom in on the time series graph to the time periods listed in the table below. In the table you are given a one thousand year range to examine. You will look at all points in that thousand year period by running your cursor over the points. You will note the concentration of CO2 for each point and then estimate the average for that range. Complete the table below by answering the following:

• What is the range of years for each high to low period listed?
• What is the estimated low CO2 concentration for this period?
• What is the estimated high CO2 concentration for this period?
• Subtract your estimated low CO2 concentration from your estimated high CO2 concentration and divide by the range of years.

CO2 For Year 2 CO2 For Year 1

Year2 – Year1

• Determine the average rate of change per 100 years (century) for each time period by multiplying your estimated rate of change per year by 100.
Time Periods Years Ago Range of Years
(Between Low and High)
Estimated CO2 concentration (ppm) Estimated Rate of Change
(ppm/year )
Average Rate of Change for estimated CO2 concentration (ppm/100 years)
Low 340,456 340,456-
332,919=
7,537
200.7 298.6ppm-200.7ppm=80ppm/10,000 year=0.013 ppm/yearppm (0.0013˚C/year) x 100 years = 0.13˚C/100 years
High 332,919 298.6
Low 252,739
High 242,346
Low 138,185
High 128,609
1. What is the average rate of change for the three time periods analyzed in the table above?
2. Check the box for temperature on the interactive graph. Compare the patterns of CO2 concentrations and temperature anomalies over the past 800,000 years. What do you observe about these patterns?