bottletop, as I keep saying we don't know the impact. There are other factors that have to be taken into account, not least of which is the powerful carbon sink - our oceans. If the greatest scientists of the world with the most powerful supercomputers can’t get the models right, how are we to know the impact? Positive and negative feedbacks are both numerous and ill understood. Here’s one example of what I mean.
Increases in water vapour form clouds and rain in the atmosphere, which in turn "washes out" and returns CO2 to the oceans thus acting as a negative feedback mechanism. However, water vapour also offers a positive feedback process. It’s actually a more potent greenhouse gas than CO2; and there’s a lot more of it. CO2 only makes up 0.03% of the atmosphere. Water vapour on the other hand makes up much more. So, what’s the net effect of these two competing feedbacks? No one really knows as the computer models are woeful. It’s not really surprising that computer models don’t take this into account very well as modelling the formation of clouds and water vapour distributions is not a simple thing. Yet this is just scratching the surface as there are many more other types of feedback loops impacting climate change.
So, the bottom line is we don’t fully understand the impact of increases of CO2. What makes it even harder is these variations are tiny compared to historical variations. Yet we don’t even understand the impact when they were larger in the past let alone now. So, how the hell can we say with any degree of confidence that CO2 is causing global warming? Absolutely none for now.
