Read here. The AGW hypothesis claims that the world's oceans have significantly warmed due to human CO2 emissions, and will continue to warm at an accelerated pace. The IPCC climate models were programmed to assume this ocean warming assumption. Reviewing the major research studies on this issue over the last decade, it's been found that the oceans have not significantly warmed, and more importantly, have actually cooled (lost heat) in recent years. This behavior runs counter to every IPCC climate model. In addition, one of the studies points to the oceans acting as a giant climate thermostat incorporating negative feedback mechanisms. The negative feedbacks prevent the global warming from achieving any type of "tipping point."