A sediment core drilled from the seafloor near West Antarctica has revealed the southernmost wildfires ever documented. The core, originally studied for evidence of a Cretaceous rainforest, also holds tiny charcoal fragments, amber, and chemical residues from burnt plants. Researchers identified these as remnants of fires that occurred roughly 90 million years ago, when the region was far warmer and wetter than today.
The fires appear to have been low-temperature surface blazes, based on how light reflected off the charcoal particles. That detail matters because it distinguishes them from intense crown fires or smoldering underground peat fires. The same core showed a shift over time from a landscape of conifers to one dominated by ferns and sphagnum moss, with a drop in pH consistent with peat bog formation. As the ecosystem changed, fire markers increased, suggesting that repeated surface fires helped keep the landscape open and encouraged peat-loving plants.
The ancient Antarctic peat bogs behaved much like modern ones, which also experience low-intensity surface fires when healthy and wet. One researcher noted that the 90-million-year-old sphagnum spores look nearly identical to those from Scottish bogs of the past 10,000 years. The findings offer a rare glimpse of how fire shaped a polar ecosystem during a much warmer period in Earth's history. As one paleoecologist put it, the fossil record shows that the present is just one data point for how the planet works. The study was published in Communications Earth and Environment. [Source: AGU Eos]