Why large amounts of methane may be even worse than thought

Large methane releases lead to strong aerosol forcing and reduced cloudiness

This paper can be available in full via that link, and it sounds pretty important for long term climate change issues.

As it explains at the start:

Among the various worst-case scenarios for catastrophic climate change suggested over the past decades, the so-called clathrate-gun hypothesis (Kennett et al., 2000) is one of the
most dramatic. In this scenario, a rise in temperatures leads to the destabilization and subsequent release of methane clathrates in the Arctic permafrost and seabed into the atmosphere, vastly amplifying the initial warming. This type
of mechanism has been suggested as a possible reason for millennial-scale warming during the last ice age, as well as the Paleocene – Eocene Thermal Maximum (PETM; see e.g. Kennett et al., 2000), though the evidence so far is inconclusive (Clark et al., 2008; Sowers, 2006). One criticism of the hypothesis is that the amount of methane estimated to have been released during the PETM is not sufficient to explain the observed warming, at least if only the longwave radiative forcings of CH4 and its oxidation product CO2 are accounted for.

They go on to note that, although most consider the large scale release of methane from clathrate reservoirs under the oceans during this century is improbable, it's important to look at what would happen if we did get a surprise.

The result would be, they think, less clouds, and therefore:

Together, the indirect CH₄-O₃ and CH₄-OH-aerosol forcings could more than double the warming effect of large methane increases. Our findings may help explain the anomalously large temperature changes associated with historic methane releases.

To which Andrew Bolt will say - but Tim Flannery bought a house on the water.