So-called “zombie fires” in the peatlands of Alaska, Canada and Siberia disappear from the Earth’s surface and smoulder underground during the winter before coming back to life the following spring. These fires puzzle scientists because they appear in early May, way ahead of the usual fire season in the far north, and can reignite for a number of years.

Most scientists believe that zombie fires are the remnants of fires on the surface, but we have identified an alternative cause. Our research suggests that rapid atmospheric warming above ground can cause peat soils to suddenly heat up to smouldering temperatures underground, all without any spark or other ignition. These zombie fires may be a case of climate change-driven spontaneous combustion.

Zombie fires have even been recorded near the coldest village on earth, Oymyakon in north eastern Siberia.

Indeed, zombie fires are an example of a rate-induced tipping point, where a system fails to adapt to too-fast changes in external conditions and transitions from its regular state to a different, often undesired state. It is possible that the contemporary climate is approaching – or has already exceeded – dangerous rates of change for certain natural system, such as bioactive peat soils, which could explain the recent increase in zombie fires.

It appears that the only solution to prevent further zombie fires is to limit climate variability.