IANAS but it never made sense to me that global warming would be linear with amount of CO_2, at some point, I figured 95% of the available IR would be absorbed

IANAS but it never made sense to me that global warming would be linear with amount of CO_2, at some point, I figured 95% of the available IR would be absorbed by the atmosphere and doubling the CO_2 would only get us to, like, 97.5%. Then again, we are experiencing some crazy weather patterns recently. Other effects of CO_2, like ocean acidification can be seen through both direct chemical measurement and by the observed environmental effects on coral reefs.