Reconciling Facts with Behavior (1/2)

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: Here you will find clear descriptions of what you just saw, how they know what they said they knew, why they know it to be trustworthy information. Finally we will ask the question, "So what!" and explore why the information is important.

WHAT do we know?

Dr. Kiehl opens his introductory talk, "Nature Visible and Invisible," at a 2006 workshop he helped to organize on “Exploring the Boundaries of Nature.” He outlines his career in physical science and chemistry, which spans over 25 years of work on understanding past, current, and future climate systems. Dr. Kiehl then describes how all of his training in natural science was inadequate to address the fundamental question of why humankind has yet to respond to its awareness of its own role in affecting climate change in a way that protects the Earth and the habitability of the planet.

HOW do we know?

Dr. Kiehl’s concerns are based on climate projections drawn from models. Scientists use models to help predict future circumstances. These models are created using known information about the factors involved and past records. Using this information, scientists can make educated guesses about how a system, such as Earth’s climate, may behave in the future. Models can be checked for accuracy by running them for a period of time that has already passed and then comparing them to actual observed conditions. If it is a reliable model, the observed conditions should match well with the model's output.

WHY can this be trusted?

Scientists such as Dr. Kiehl are able to use models to make reasonable predictions about the future because there are certain physical relationships and properties that hold true. For example, carbon dioxide is known to be a greenhouse gas—one that holds heat in the Earth’s atmosphere.  Therefore, there is a potential relationship between carbon dioxide concentration and global temperature. These relationships can be used to create formulas that are plugged in to the models.


Acknowledging future changes is an important step toward reducing consequences of those changes. But knowledge about the future is only useful if coupled with actions that reduce the rate and scale of change.  Dr. Kiehl’s knowledge of Earth systems tells him that a lack of corrective action in reducing greenhouse gases will lead to radical changes in life as we know it. In order to address those changes scientists need to consider ways to improve their ability to communicate their concerns to the public so that the public can make informed decisions about potential action. 

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The complete PowerPoint of this presentation is available on AGCI's website.

Kiehl, J. (2011). Lessons from Earth’s Past. Science. 331: 158-­‐159.
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