Students should use the Climate Time Machine to help them answer these questions on the student sheet. This sheet provides you with some answers to the questions.
What did you notice when looking at the time line?
Answers will vary but should include the observation that the amount of sea ice has decreased over time.
Look at the three main colors in the graphic: red, white, and blue. Label each color to identify it:
Red is the sea ice boundary; white is the sea ice; and blue is the water.
If we analyze this graphic in terms of three colors—red outline, white ice, and blue water—what does it tell you about earth's temperature when there is the most white?
Students could infer that when there is the most white in the graphic, that means there is more sea ice and therefore, the earth’s temperature is colder than in other years.
What do you know about heat that makes you say that?
Answers will vary but could include the observation that if the temperature is colder then that would mean there is less heat in the atmosphere.
In what year is there the least white?
2007 is the year with the least white.
What year was the sea ice largest? Hint: Look for the year with the biggest white blob!
1979 is the year when the sea ice is largest.
What does it mean when the white gets smaller and the blue gets bigger? What is happening? Another way to express that change is that, over time, more and more blue appears within the red boundary from 1979-2010. What is creating more blue?
White ice is melting into blue water. This happens when extra heat is transferred back to earth from trapped greenhouse gases.
Let's look at that year 2007. How does that compare to 2010 and 2000?
It looks like there is less sea ice in 2007 than in 2010 or 2000.
How do we make sense of that? If the white blob got bigger after 2007, does that mean climate change ended?
No. It means the climate change process, like most processes in nature, has variation. Some years have more heat transferred back to earth than others, some years have less. This graphic suggests the time from 2007-2010 was a slow-down in the amount of heat transferred back to earth. The overall TREND of the direction of heat transfer is what is constant and important. And you see the trend in 2010 by comparing the red outline with the white: In 2010 the white blob edges no longer touch the red outlines as they once did in 1979, because so much white ice has melted into blue water. This tells you heat transfer has been TOWARD the earth, causing sea ice to melt during this period.