Science Buddies: "Ask an Expert"

How could i describe prevention of global warming in a Model.
I am thinking to make the model of size - 2*2 M . Wat things should i put in it the model?? How should i make it?? How could i show prevention of global warming is main question..

Unfortunately you are starting with a premise that maybe false. The questions associated with any global warming hypothesis are well beyond what anybody can model accurately enough to draw accurate conclusions with today's knowledge. To presume that one could build a physical model in a few cubic meters and hope to be anywhere close to a scientific methodology. There is / was a geosphere project in Arizona that tried and failed miserably from which we learned a lot.

The facts associated with the mean (average) earth temperture are hard to come by. In geologic terms, we know there have been several ice ages where glaciers have covered large portions of the earth with tropical or subtropical conditions inbetween based on our interpretation of fosil records.

Most of these past events occurred long before there were enough humans around to to even consider our ability to alter climates. Given this, how could one expect that man has a lot of influence on the mean earth temperature?

If you model the earth using some gross thermodynamic models, most of the energy arriving is radiant energy from the sun. I'm not sure how anybody could turn down the sun. Back before we spent lots of money on cleaning particulate matter from smoke stacks, we probably had more of an atmospheric filter that blocked a larger precentage of the arriving radiant. In years following major valcanic eruptions far more of this blocking material is put into the air than smoke stacks could create in the same time.

Our sun is a "red giant". There plenty of astronomy evidence that red giants tend to expand and increase their mean radiant energy output as they age.

Planitary orbits tend to decay over time so the mean earth sun distance is probably decreasing which will increase the radiant coupling between the sun and the earth.

One could spend ones lifetime contemplating this issue and hardly scratch the surface with any scientific basis.

Craig_Bridge wrote:Unfortunately you are starting with a premise that maybe false. The questions associated with any global warming hypothesis are well beyond what anybody can model accurately enough to draw accurate conclusions with today's knowledge. To presume that one could build a physical model in a few cubic meters and hope to be anywhere close to a scientific methodology. There is / was a geosphere project in Arizona that tried and failed miserably from which we learned a lot.
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One could spend ones lifetime contemplating this issue and hardly scratch the surface with any scientific basis.

Craig is right. The science behind climate change is pretty complicated. You should do some background reading on climate change as a while, and then maybe pick one small area to model. You would have to research one small topic in a lot of detail, and make that a model for part. It won't be the same as the whole, but it probably the best you can do.

The geosphere project is a good example of how complicated even a small system can be. Here is a link to some information about that:
http://en.wikipedia.org/wiki/Biosphere_2

Oh, and as Craig also mentioned, average temperature change ("global warming") is a pretty poor metric for a variety of reasons. There is certainly variability in mean temperature with time that is not caused by human influences (like the ice ages he mentioned). There are also temperature changes causes (or appear to be caused) by human activity. And a mean temperature obscures the fact that climate change will effects different places in different ways.

Anyway, here is a wikipedia link on global warming.
http://en.wikipedia.org/wiki/Global_warming

As you read on this topic, be sure to separate scientific fact from political opinion. In this particular debate, these two topics have been mixed together. The scientific question is, "Is there evidence that man has influenced earth's climate?". The political questions (for example) are, "Is this a bad thing? What should we do about it (if anything)? What cost are we willing to pay?" Frequently, people seem to start with the answer to the political questions, and use that to judge the scientific data.

Since this is a politically charged topic, it is always worth noting where the information comes from. Anything summary from, for example, a think-tank, needs to be viewed with a hefty dose of skepticism. Are they pushing a particular political agenda? Have they selected the data just to support their political ideas? You should apply the same standard to proposed solutions to 'global warming'.

Louise

For using physical models, I would suggest something small and simple. It might take a lot of trial and error to get a decent experiment, and you do not want to have to rebuild a 2x2m physical model.