Yes, it's true that temperature and precipitations are the most important parameters to evaluate tne climat change, but there is another parameter which is important too, it's homo sapiens (human).

There are many models of differing types. Those commonly used to predict CAGW climate change are global circulation models. These are very complex and require many educated (and some uneducated) guesses about the efficacy of climate processes. Climate models are worthwhile efforts to better understand our climate system but are very approximate in their predictive capabilities. Hence, their conclusions regarding CAGW have failed, considerably overestimating the relative significance of anthropogenic climate forcings relative to natural ones such as variability of the total solar irradiance. 

There are a lot of models to evaluate the climate change.But all of the models predict that if the world continues to rely on carbon-based energy, population growth continues at its current annual rate and ‘dirty’ technologies continue to be used, global average temperature may increase by 2100. Also we can see the below reference for more information.

Randall, D.A., R.A. Wood, S. Bony, R. Colman, T. Fichefet, J. Fyfe, V. Kattsov, A. Pitman, J. Shukla, J. Srinivasan, R.J. Stouffer, A. Sumi and K.E. Taylor, 2007: Cilmate Models and Their Evaluation. In: Climate Change 2007: The Physical Science Basis. Contribution of

Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Available at:

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CCEQFjAB&url=http%3A%2F%2Fwww.ipcc.ch%2Fpdf%2Fassessment-report%2Far4%2Fwg1%2Far4-wg1-chapter8.pdf&ei=tTkVVNnqHM_caKbtgNAI&usg=AFQjCNFLeMJqxgu1H9_-fYgq6kqBzx5rLQ&bvm=bv.75097201,d.bGQ

Thank you

It is still very difficult to project precipitation applying the current climate models. Other tools would be also important.

climate change uncertainty is very high..because the climate system's very complex and not all phenomena accomodated in generic formula that solved by computer and more parameterization to solve complex natural event..also error from computer model itself !!!!!!but from obersevation evidence it's clear that eath's global temperature changes.

I have my own aproach that diverges from the rest, I have writen and documented and detailed described that, and discovered the mechanisms involved in climate varibility

https://www.researchgate.net/profile/Dimis_Poulos