I think the most important information to take from all this as others have already said is not to believe what the government sponsored lobby groups (IPCC) are reporting as they have fairly weak scientific credentials but to foucs on the peer-reviewed scientific information. Unfortunately this highlights a key problem in how science is communicated to the masses as the vast majority of peer-reviewed journals are only available if you pay a hefty fee or reside at a university. Even when the media pick up on a journal article they are always going to put their own spin on it which again prevents most people from being able to access the actual science.
Other than knowing that humans are increasing greenhouse gas emissions and that these gases are able to trap heat and raise temperatures everything else is just based on models and speculation. It's not known how much of an effect rasied GG levels will actually have on temperature. It could be anywhere from almost zero to up to several degress. The real problem comes in the form of how the Earth will respond to these changes. There are so many feedbacks involved that it is currently impossible to make an accurate prediction which takes all these effects into account (not to mention we don't know how the Earth's natural climate will change and whether human interference will negate natural changes or amplify them).
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