Global Climate Change Introductory Lecture


Purpose of this course:

Course mechanics:

What are the questions we need to address in a course dedicated to global climate change? If you ask many people whether global warming is occurring they respond as if the question was - is human behavior causing global warming. Those are actually two different questions. Global warming could be occurring, but not due to human behavior. Indeed, it is possible that human behavior could contribute in a significant or insignificant way, and the second question might be better phrased - to what degree is human behavior contributing to any climate change. It is thus important to be explicit about what question(s) is(are) being addressed in a discussion or debate. It can be a productive debate tactic to switch to another related questions, or to purposefully confuse questions, but this is evasion and not science. Use of such a tactic is not designed to try and provide the best answer for the question, but only to 'win' the debate.

A basic working model for atmospheric energy flux.

Important physics: albedo, black body radiation, convection, negative and positive feedback loops.

Ways to theoretically change the energy flux and cause global climate change? Change any of the explicit or implicit relationships between system components above. Simearth! Possibilities are explored below.

Change in energy input:

Change in atmospheric albedo:

Changes in surface albedo:

Changes in atmospheric gas content:

Changes in hydrosphere-atmosphere circulation patterns.

This is rich behavior indeed and geologic history shows the richness of this behavior.

Next time - take a planetary perspective, comparing the history of atmospheres on Earth, Mars and Venus.


Discussion question:

What factors may have contributed to the diverging paths of the three planets, Venus, Earth and Mars, and discuss which you believe were the most crucial factors?