The green house effect

Yasmin Jayathirtha

silver-coins All students study environmental science from a young age and the newspapers carry a lot of stories on environmental issues. Global warming is hot news these days (joke intended). However, the stories while giving data and details are not very informative about the science behind the predictions. Much of the forecasts and speculations are based upon models of how this very complex system operates and what perturbs it. We build up a model using a few parameters and see whether the model agrees with the reality. If it does not we will have to consider other factors and add them in. This uses knowledge of how simple systems behave but in modelling we learn how the various systems interact with each other. The science is robust and the computers have become powerful enough to deal with large and varied data. However, we (the lay people) pretty much have to take it on trust and if there is any query or dissent, we do not know whether it is a real failure of the model or a denial of an ‘inconvenient truth’. While the subject is called EVS or environmental science, much of the classroom work for school students is theory based.

To explain the greenhouse effect and global warming, we use examples of the greenhouse itself, how a car with the windows closed heats up, how the atmospheres of Venus, Earth, and Mars contribute to their temperatures and so on. But it is good to see if we can model some of the effects. The experiments that follow also illustrate a very important principle; that when we set up a model, we pick and study one factor at a time, so controls are very important. We may be leaving out factors that do make a difference and so we find that a strong effect does not show up in the real world. Our models will also exaggerate the conditions so that the effects will be seen clearly. This may sound a little irrelevant, but will make sense when one considers the experiments.

The author works with Centre for Learning, Bengaluru. She can be reached at

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