We have had very smart people working on climate change models for decades and no one ever looked into that?

The problem isn't that no one has looked into it. The problem - and this is a general one for any scientist working in climate change or environmental protection - is that we can't afford to raise a single false alarm. We can't publish bad news unless we're 100% certain, because that will give oil companies' lawyers and 'journalists' enough ammo for the next fifty years. This means that published climate predictions are usually the most optimistic and conservative estimates.