Global warming estimates - are they flawed?

Reviewing material from global warming estimates, anyone who questions the validity of the figures or the methodology used to obtain these figures is immediately decried as a climate change skeptic.

Science is all about robust debate, the people who are trying to shut down debate really run against the principles of science. The debate to question the methodology of the estimates must be questioned, has the scientific community used flawed models to reach these conclusions?

Citing a different source, there is little doubt atmospheric CO2 has risen in line with advancing industrialisation, the question is, is it purely carbon dioxide in the atmosphere or are other factors affecting the climate? One of the byproducts of industrialisation is the building of infrastructure, is the decrease in forests and more importantly the trees that absorb CO2 the issue?