[Off-topic] xaccers:
I'm sorry you weren't able to grasp the point I was making by mentioning my geography teacher.

It is wrong for a teacher, especially a science teacher, to put forward their opinion as fact, or be unable to seperate their own opinions from good science.

It doesn't matter if she believed australopithecus africanus was a chimp like creature unrelated to man, she should have put her beliefs aside and marked according to the quality of the science and research put in front of her.

Likewise your teacher should have given you the tools to understand global warming and climate change rather than opining that it is a hoax.

The Martian ice caps are the Martian atmosphere! What do you think they are made of?

It's frozen CO2 which is pretty much all that is left of the Martian atmosphere, the rest has evaporated off into space.

Mars is tectonically inert, it has very little internal heating, it's got low gravity which as I've explained is why the atmosphere is able to escape.

As I've said, during the Martian summer, the poles recieve more solar engery and the CO2 sublimates back into it's gasious form. A gas is made up of excited particles rushing around bouncing into each other, and many will have enough energy to escape Mars' gravitational hold, evaporating off into space.

You comment about volcanoes and greenhouse gasses on Venus is somewhat confusing.

Let me try to explain a few things so I can see if we understand each other.

Venus is very tectonically active (unlike Mars, and the Earth is somewhere in between), which releases lots of CO2 into it's atmosphere. It's oceans boiled away and there is no precipitation (rain) to clean the atmosphere so unlike on Earth, there is no Carbon cycle.

Consiquently the levels of CO2 built and built and built to their bone crushing levels of today.

The volcanoes are not heating Venus significantly, although it would be a bit warmer by a volcano than away from it obviously. The CO2 isn't heating Venus either. The Sun provides the heat, but this is the important bit which you appear to be having a spot of difficulty understanding, the CO2 traps the heat, meaning that Venus gets hotter than it should be, considerably hotter than it should be, hot enough to melt lead.

With every eruption of CO2 into the atmosphere, the amount at which Venus is hotter than it should be increases (in case you're thinking along the lines that Venus' temperature is constant despite all that CO2).

Now if you were to remove all the CO2 from Venus' atmosphere, it's temperature would drop to what it should be. Got it?

On the Earth, we have rain, and life, which gives us a Carbon cycle.

CO2 released into the atmosphere by animal and plant respiration (yes, plants produce CO2, isn't science amazing?), burning fossil fuels, volvanic activity etc is reabsorbed by the oceans (making them acidic) and plant photosynthesis, and the soil, and concrete, and various other processes (such as dead organic matter that's been buried).

Now if we just burnt a sustainable amount of young trees for our energy, replanting as we chop them down, then there wouldn't be much of a problem.

The CO2 that we were releasing would be the CO2 absorbed by the trees as they grew (of course they release the oxygen leaving just carbon which we then oxydise -burn- putting the oxygen back forming the CO2 produced).

The carbon cycle is pretty balanced for the levels of CO2 we're supposed to have.

Now if you go back millions of years to when that zooplankton was growing before it became crude oil, it's absorbing CO2. Then it died, became buried and turned into crude oil. Basically think of crude oil as stored CO2.

So imagine what would happen to the balanced carbon cycle if we went back millions of years, sucked up a load of CO2 and then released it today.

The cycle gets overloaded, trees may absorb more and grow bigger, but they'll die and release the CO2 back unless we bury them, and if we burn them then they release the extra CO2 even quicker. The oceans absorb more CO2, forming carbolic acid which kills coral and other primary food sources (we're seeing this already). The atmosphere traps more heat, which raises the global temperature above what it should be altering weather patterns. Precipitation increases and there are more floods destroying crops and people (look at Bangladesh), the temperature of the oceans increases killing more coral and primary food sources (many reefs have been bleached through high temperatures).

We're seeing many of these effects already, and that's with only a slight increase in temperatures above what they should be.

Hopefully the Sun's activity will remain depressed and we can play catch up for a little while before it's too late.