Scientists' Explanation for Investigation 1

A Comparison of Carbon Dioxide and Temperature Before the Industrial Revolution

When you examined the 800,000-year temperature data set in the last module, you learned that cyclical patterns of glacial and interglacial periods occurred approximately every 100,000 years. In this exploration, you should have observed that CO2 patterns closely track temperature anomalies. The following video starring Dr. Richard Alley describes how CO2 and temperature are determined from ice core data.


You also should have noticed a lag in this data. On this graph, you saw that the concentrations of atmospheric CO2 lag about 1000 years behind the temperature anomalies. What causes this lag? Oceans are a major sink or absorber of CO2, and when temperatures rise, they release CO2 into the atmosphere. This explains the patterns over the past 800,000 years, but not the more recent trend for CO2 and temperature anomalies.