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ICP Website Curator: Robert B. Schmunk — NASA Official: Gavin A. Schmidt


Global Equilibrium Energy Balance Interactive Tinker Toy

Using a Spreadsheet Climate Model in the High School Classroom

With the bountiful help of Dr. Andy Lacis, I have been modifying the original ICP Excel Climate Model so that it presents a more accurate picture of the factors and interrelationships that produce the temperature at the surface of the earth. This new model (the Excel Version of GEEBITT, the Global Equilibrium Energy Balance Interactive Tinker Toy) allows the user more versatility in selecting parameters that can be changed within the model. Currently the Excel Version of GEEBITT deals only with the factors affecting incoming solar radiation and produces a temperature corresponding to the global average temperature for the inputted conditions. Eventually this model will also include the effects of the long-wavelength (infrared) that is radiated upwards from the earth's surface. In its current state the model does a realistic job of portraying the effects of changing surface features, changing atmospheric constituents (a variety of aerosols, several gases - oxygen, carbon dioxide, water vapor, ozone) and changing cloud properties. Through controlled model experiments, students will be able to identify how each of the parameters acts as a forcing and the magnitude of the changes in temperature that may occur in the real world. The limitations of the Excel Version of GEEBITT, and more so the introductory version of the model (the ICP Excel Climate Model) will help the student understand the limitations of the GISS General Circulation Model (GCM). The use of these simplified models can serve as a bridge for students working with data from their own observations to working with data from the GISS GCM. The Excel Version of GEEBITT will most likely be used after an introductory series of activities involving the similarly appearing ICP Excel Climate Model. The activities below describe how this introductory series of activities could be carried out.

The GEEBITT Excel models are:

  • Mini-GEEBITT Version A3
    A simple climate model to be used to conduct experiments on factors that influence planetary temperature: luminosity of the Sun, albedo, and distance from the Sun.
  • Mini-GEEBITT Version B3
    A simple climate model to be used to conduct experiments on factors that influence planetary temperature: luminosity of the Sun, albedo, distance from the Sun and the absorption effect of a planet.s atmosphere. This GEEBITT includes the Greenhouse Factor.
  • GEEBITT - Full Version
    A simple climate model to conduct experiments on the radiative effects of a planet under various conditions: Black Body, Reflective Surface, Raleigh Scattering and Aerosols, Clouds and Stratospheric and Tropospheric Components. This stand alone version includes data tables in which the investigator may save data for analysis at a later time.

The Question and the Motivation

A variety of activities could be planned around the ICP Excel Climate Model. The main climate research question that would be addressed by using this model is: "How does the earth maintain its temperature?". The motivation that would propel any activity using the model is the limited range of temperatures within which life as we know it can exist. More simply, if the earth gets too hot or cold, life will disappear. A simple discussion of where people live on the earth today and why they choose to live there could lead off such a discussion. Why don't people vacation in the arctic for the Winter, or the desert in the summer? Based on current conditions in which the average temperature is 15°C, the instructor could then proceed to what-if scenarios of what would happen if there were another ice age or if global warming increased the temperature of the earth. What are the factors that determine/regulate the temperature of the earth? What role, if any, do humans have the regulation process? Appropriate videos of extreme weather events would help to drive these points home - especially videos of people ineffectually trying to battle overwhelming floods, storm surges and dust storms.

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