Concerning divergent hypotheses on climate change cause:
The article on scientific opinion on climate change (http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change) is twice as long as the one for climate change itself. This is mainly because it is a very dear topic that is constantly, erroneously (but effectively) 'discredited' by 'news outlets'. It is very important that the world know, beyond a doubt, that there is a scientific CONSENSUS that climate change is caused by human activity -- specifically the release of CO2 into the atmosphere through combustion of fossil fuels.
Yes the models need to be adjusted, they will be, repeatedly. But it doesn't change the fact that the problem is somewhere between bad and hellish.
Cosmic rays, as the previous comment suggests is an example of a differing hypothesis that may explain the same observations, is the theory that decreased activity from the Sun (sunspots and related activity) decreases the protection provided from solar wind and increases the effect of cosmic rays on the planet (reducing cloud formation/cover). This hypothesis has been calculated to contribute, at maximum, 10% of the change we have observed, and, since this is a cyclic process(the ebb and flow of solar activity) on the order of 11 years, historic data can show the effect during previous cycles*.
*'Cosmic rays, solar activity and the climate',T Sloan and A W Wolfendale, 2013, Environ. Res. Lett., 8, 045022
Also Check http://www.skepticalscience.co...
for this topic.