The problem with global warming theory at the moment is that there IS scepticism among the scientific community (in terms of activists, almost as many who support the theory). Which are completely discredited by the media who are in search of propaganda story to sell papers. The end of the world is quite a good story to sell. Lets look at the theory. The earth can be approximated as a black body radiator. It is hot, so gives out heat. We can very accurately work out the intensity and frequency of this outputted radiation. we can also work out how much heat is lost to space. Using all of this data, you can work out what the temperature SHOULD be at the earths surface, I can't remember exactly what this is, but its either a couple of degrees above of below 0 celcius. So there is a problem, using the tried and tested thermodynamical calculations you learn in the first couple of years of univerisity, the earth should be cold. Why is it not? This is where the 'greenhouse theory' comes in. In basic terms, heat from the earth is absorbed and re-emitted back down towards earth, raising the temperature. So back to the lab. Quantum theory dictates that molecules can only absorb-emit specific frequency photons, to do with there vibration modes. Carbon dioxide is one of the molecules that absorb and emit the photons that should be emitted from the earths surface. In fact, carbon dioxide emittance falls very close the the peak intensity of the black body curve of the earth. So we look back on temperature and carbon dioxide levels, and there IS a correlation. Knowing all of this, I don't believe in the theory. Why? well, a number of reasons. for example, the warming of the atmosphere should be just actually be greater at higher altitudes. When all satellite data says the warming is greatest at ground level. In fact some satellite data shows there has been little to no warming even there. There is also all of the statistical errors and generally bad science highlighted by the climate gate scandal. What must be realised is that any small error made is magnified many many times by climate forecasting. Imagine your year on year predictions are 98% accurate. Quite high you could say, given the complexity of the climate. But we are now going to look at the long term forecast. Each year that error becomes bigger and bigger, (0.98^y)*100 (y is years) is the accuracy of your prediction, after 5 years you are 90% accurate, after 10 years 80%, after 25 60%... As is common knowledge, predicting the weather is no where near 98% accurate, The metoffice itself recently stopped TRYING to predict the weather 5 years in the future. So the predictions we have cannot really be trusted. Is there any long term model that is proven to work? You'd think not given how new climate science is. Well, there are known correlations. Look at the price of rice. The price of rice is inversely related to the yield of rice crops, the better the yield, the more rice on the market, the lower the price of rice. Now, in years when it is very sunny, rice grows better. What makes it a more sunny year? Ironically, the sun. Before I explain how, I must first give a brief lesson on cloud formation. Clouds are water vapour, but there is water vapour in the air now, yet its not fogging between me and my computer screen, what makes water vapour turn into clouds? The answer is charged particles. Fire a charged particle through a chamber with alot of water vapour and you will see it has formed a trail of cloud. This was used to discover the positron (anti-election), the electron would be fired through the 'cloud chamber' with a constant electric field applied to it, and you will see a cloud trail curve to one side ( I think clockwise...) and fire a positron through the same chamber and it will curve the opposite way. This is how clouds are formed in the atmosphere. Radiation from other galaxies hit the earths atmosphere and clouds form around the paths, the wind blows the clouds and the clump together. Now. In times of high solar activity (when our sun is very active) the radiation from our sun becomes very strong, this is called the solar wind. This wind prevails at all times, and in fact is thought to save the earth from the worst of the galactic radiation by 'blowing' it away. The stronger the suns activity is. The stronger the solar wind, the more charged particles are 'blown' away, the less strike the earth, the less clouds are formed. Less cloud formation, means it is more sunny, and the rice crop is better. SO.. using this knowledge you can plot a graph of sun spot activity (as seen by astronomers for hundreds of years) and the price of rice ( as documented by merchants for hundreds of years) and, as expected, there is a correlation. sun spot activity goes up, price of rice goes down. So we have a fact. The more galatic radiation that hits the earth, the more cloud is formed, the more sun is reflected. Also, if lots of the suns light is reflected, common sense says the earth should have a lower temperature. This is in fact how the ice ages happen, the more ice over the earth, the more sun gets reflected, the colder the temperature, the more ice formations etc... The main alternate theory for global warming is that we have going through a period of low galactic radiation. This is also predicted by the orbits of solar systems.