The math on the 140 ppm increase in CO2 from around 280 to 420 ppm is calculable and doesn't yield much warming on its own. Then you get into complex feedback mechanisms to explain what is observed. I've looked into the various models and agree they, to my way of thinking, are way way too complex to be predictable, and in fact, they are complex so they can "match" what we observed in the past. That can be OK, but then again, "All models are wrong, some are useful".
I'm also unclear why there are four or five major models, with very different weighting factors and components, it makes me "nervous". And the "bad news" is that it's about equally probable they are too conservative, things could get worse, a situation we've discussed a bit here, sudden melting of permafrost for example, you hit a kep balance point and the climate really goes to hell.
My bottom line is "I don't know." One thing I do know is that "we" are not doing anything like near enough to ameliorate the issue if this is mostly due to CO2. And we're not going to either, there is no way.
My buddy the physicist is in Algeria, he sent me a photo of sand dunes and I asked if they had any rain in the forecast. He said it had not rained there in 20 years. The next day, he sent a photo of it raining ... and we are getting unusual amounts of rain in unusual areas, my wife said Roissy airport (CDG) was almost closed due to standing water.
