About the graph Temperature Temperature is reconstructed by analyzing the amount of oxygen found in the ice core. Data provided by the University of Washington. Insolation Insolation is a measure of the amount of solar energy that reaches the top of the atmosphere. The heat and light emitted by the sun drive many of the physical and organic processes on earth. Data provided by Universite Catholique de Louvain, Belgium. Calcium The dust found in ice cores was blown by the wind from areas with little or no vegetation, falling to earth with rain or snow. Calcium dust originates from continental shelves that are exposed to the atmosphere as sea level drops during an ice age. Data provided by the University of New Hampshire. Methane Gas that is present in the atmosphere fills the air spaces between snowflakes on the ground. As the snow accumulates over time and turns to ice, the gas is trapped in small bubbles that can be analyzed to describe the chemical composition of the atmosphere over time. Data provided by the University of Rhode Island.

Information from ice cores helps scientists understand how earth's climate has varied over time. The Greenland Ice Sheet Project 2 (GISP2) drilled an ice core from the summit of the Greenland ice sheet all the way down to bedrock. A total of 10,116 feet (3,053 m) of ice was retrieved, taking four years to complete! This ice core records the past 110,000 years of earth's climate history and provides one of the most detailed records for the northern hemisphere.

The ice core was sampled for 42 different measurements that tell us something about the earth's temperature, solar radiation, sea level, and the chemicals in the atmosphere over time. We have taken some of the data for the past 40,000 years and presented them in graphs for you to interpret just as the scientists did.

Calcium (Dust)

Insolation

Methane

Compare each of the variable separately to the graph of temperature. Ask yourself the following questions:

1. Does there seem to be a correlation between each of the variables and temperature? Are they proportional or inversely proportional?
2. Is the timing between a change in any variable and a corresponding change in temperature immediate or is there a delay? Why do you think a delay might exist?
3. Describe how any part of the graph, for any of the variables, could be used to determine past or future climatic conditions.
4. If you overlay two or more graphs would your answers be the same?