Behold the Methane Monster! This is the worst positive feedback loop. As Methane extraction is furiously pursued (fracking, with short term wells) there is more leakage; but more sinister is permafrost clathrates. These hold far more fossil Carbon than coal, oil, and gaseous Methane deposits - and melting Methane hangs longer in the atmosphere, meaning more warming and harder to reverse.
Methane does not get dissolved in the ocean like CO2, it is not converted into sugar by plants and phytoplankton like CO2. It is exploding out of the Siberian, Alaskan, and Canadian arctic, bubbling out of the Arctic Ocean (which is losing its ice cap), from the conshelves down to the 40th parallel, and from the deeps all over the world.
Most of the Methane from the deeps is being eaten below the hypoxic layer by methagenic bacteria; but they are going to run out of Oxygen, and then that curve will skyrocket literally, rocket towards the sky from 1km below the ocean surface.
We have passed the tipping point.