Science works by demanding evidence and logical arguments to support claims; and by continually searching for more accurate theories. Evidence helps in interpreting and evaluating accounts of climate change in the media and elsewhere and helps to distinguish scientific fact from opinion. What kind of evidence exists that helps us determine how climate has changed over time and how it might change in the future?

In this section, you will examine the evidence for global climate change.

Data Activity: Examining the Vital Signs Travel through Earth's recent climate history with the "Climate Time Machine" interactive. Carefully examine the changes over time in sea ice, sea level, carbon emissions, and average global temperature. Reflect on the key changes in the four variables shown in the interactive by thinking about the following questions:

  • When did the key changes occur for each variable?
  • Can you hypothesize as to why these key changes occurred when they did?
  • How does this information compare with what you have heard in the media?
  • Is any of this data surprising or new to you?
Climate Time Machine

Next, view the interactive data for indicators of climate change on NASA's Global Climate Change website to give you a sense of the scale of change we have seen in our climate system.

Look at graphical and pictorial representations of data that show trends up to the present for Sea Level, Carbon Dioxide Concentration, Global Surface Temperature, Arctic Sea Ice, and Land Ice. Go to NASA's Vital Signs and for each of these indicators, consider the data source for the information, the length of time the data covers, what is being measured, and what causes the changes. What is more useful to you to understand the data-looking at the graph or the visualization?

Why should we be concerned about these specific indicators?

What impact do these trends have on our Earth?

What is your new understanding of the data sources you explored from NASA's Key Indicators?

Solidify what you have learned in this section by watching the "Warming World" video. After watching the video, return to your summary of your understanding of the data sources you explored from NASA's Key Indicators. Are there any changes or updates you would like to make to your notes after watching this video?