Penn State NASA

Module Summary and Final Tasks


Module Summary and Final Tasks

End of Module Recap:

In this module, you should have grasped the following concepts:

  • General Circulation Models (GCMs) provide us with a means to generate detailed pictures of the climate of the future. They are complex models that try to simulate the physics of the circulation of the atmosphere and oceans and the movement of heat, water, and greenhouse gases through the climate system.
  • GCMs, taken as a group, do a very good job of simulating the present climate and the climate of the recent past — this is the primary basis for trusting these models with respect to their predictions of the future climate.
  • A GCM model typically involves an imposed history of greenhouse gas emissions into the atmosphere as the force that drives changes; the emissions scenarios discussed here represent 3 very different ideas about how the world will work together (or not!) to limit carbon dioxide emissions. Even in the most optimistic scenario, the temperature of the planet rises by more than 1.4°C by the end of the century. In the least optimistic scenario, the temperature rise in the next century is more than 3°C, taking the mean of more than 20 GCM model results.
  • The Arctic region experiences the greatest warming in these GCM results — warming in excess of 20°C over the next century. This kind of Arctic warming was last seen about 3 million years ago, at a time when the atmospheric CO2 concentration is believed to have been about 400 ppm (close to today's) and sea level was about 20 m higher than today.
  • The regional differences and the month-to-month differences have important implications for where we will live and how much we will have to spend on cooling in the future.
  • GCMs also predict important changes in precipitation and surface water availability, that, for some important regions of the globe (the US and Europe) will mean not only hotter climates, but less water for agricultural use, which will present some serious challenges given the fact that we will have about 10 billion people to feed at the end of the century.


You should have read the contents of this module carefully, completed and submitted any labs, the Yellowdig Entry and Reply, and taken the Module Quiz. If you have not done so already, please do so before moving on to the next module. Incomplete assignments will negatively impact your final grade.


  • IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.