Evidence for Environmental Issues

So, whilst having a discussion with someone with quite opposite views the other day I realised that I can't quote figure or evidence for global warming. I can repeat things that have been said in the media, but no hard evidence.

Let's start from a level playing field - let's go either way. I would like people to point me toward actual scientific papers (e.g. academic or new scientist style, not the broadsheets' propaganda!) which give evidence both for and against global warming.

Thank you kindly.... comments appreciated!