The models have waaayy too many unknown variables to be useful or valid, and these variables are given values based on assumptions. After a few assumptions are added, the model becomes the assumptions.
If any part of global warming/climate change were valid, the low-lying Maldives would have been submerged years ago.
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H2O is 300-400 times more potent as a greenhouse gas (roughly the same quality and 300-400 times more prevalent). Its use in the heat cycle of the earth is clear, and unambigous. It is difficult to model however, and in order to accurately model climate change, bigger factors have to be modelled accurately first. If CO2 effect is less than the noise of H2O, then how do you know it is CO2?
DK