Huge amounts of methane are contained in sediments under the Arctic Ocean. As global warming heats up the oceans, there is a growing chance of huge methane eruptions from the Arctic Ocean seafloor.
Such eruptions can occur abruptly, rather than gradually. In the first few years after its release, methane's warming potential is far higher than carbon dioxide. In the case of eruptions from the Arctic Ocean seafloor, the methane rises in the form of plumes, making that the methane will be highly concentrated in an area where the atmosphere contains very little hydroxyl to break down the methane. Even relatively minor methane releases in the Arctic can therefore result in dramatic local warming and thus trigger further eruptions, spiraling into runaway warming.
Important in this regard is how the precautionary principle is interpreted. Risk is a combination of both the probability that something will eventuate and the severity of the consequences. The consequences of large amounts of methane erupting from the Arctic Ocean seafloor are so severe that even a small chance that this will eventuate constitutes a huge risk, which justifies a serious response. Accordingly, the precautionary principle should lead to comprehensive and effective action to reduce the risk.
A political position that is all too common among scientists and politicians is that merely lowering carbon dioxide emissions would suffice to get us out of our predicament. This position is then often presented as an article of faith, closing the door to scientific analyses that conclude that more comprehensive and radical change is needed.
Granted, the precautionary principle also calls for further debate and study into ways to improve the situation. But this doesn't mean that inaction was acceptable. Everyone has a duty of care about the mess we leave behind. In many cases, time will heal the wounds. In this case, however, we're rapidly running out of time.