Global Warming & such

I'm kind of amused by web sites that say what to expect from climate change in the next few years, as if all it'll mean is maybe, worst case scenario, the atlantic conveyor current, aka the Gulf Stream switches off, leaving the UK with Russian style winters. Almost nobody mentions the Clathrate Gun Effect, or the possibility of a Runaway Greenhouse Effect. Basically, in Alaska & Siberia, there are tonnes of methane trapped within the ice crystals. When the Earth gets warm enough for the poles to melt, these methane clathrates will melt, releasing all that methane into the atmosphere. Essentially, when the poles melt, we'll reach a point of no return, like a drowned body that gets deep enough that the water pressure crushes the gases within it till there's no buoyancy, and the body will never again surface, or like a house fire that finally burns through the wall of the gas main. The Worst Case Scenario with global warming is essentially mass extinction, possibly the end of all life on earth. Methane clathrates are one of the main suspects in the Permian-Triassic Extinction Event, during which 96% of all marine species and 76% of all land-based species became extinct. More about this here.
Of course, the real worst case scenario, is Venus. Think about it.