Antarctica is synonymous with ice today, but during the Late Cretaceous, around 90 million years ago, the continent looked dramatically different. New research led by scientists from the Alfred Wegener Institute has revealed that wildfires regularly burned in forests growing close to the South Pole, making them the southernmost known wildfires ever identified on Earth.
The findings come from the analysis of a sediment core recovered from the Amundsen Sea region of West Antarctica. Earlier studies of the same core had already demonstrated that a temperate rainforest once flourished near the South Pole under a much warmer global climate. The new investigation uncovered clear evidence that fire was a recurring feature of this ancient ecosystem.
Researchers identified microscopic charcoal particles throughout the sediment sequence, indicating repeated burning of vegetation over time. The charcoal suggests that many of these fires were relatively low-intensity surface fires that consumed forest litter and undergrowth rather than sweeping through the canopy. Additional evidence came from fossilized tree resin, or amber, which appears to have been produced by trees responding to fire-related damage.
The team also found abundant remains of peat moss, pointing to the existence of extensive peat-forming wetlands. Rather than being destroyed by fire, these peatlands may have been encouraged by it. Periodic burning helped keep parts of the forest open, creating conditions that allowed peatlands to expand and accumulate carbon-rich organic material.
The research paints a striking picture of Antarctica during one of Earth's warmest periods. At the time, the region experienced mild temperatures, seasonal darkness and periods of intense rainfall. Lightning associated with seasonal storms likely provided the natural ignition source for many of the fires.
Beyond reconstructing Antarctica's ancient landscapes, the study offers insights into the long-term relationship between fire, vegetation and carbon storage. The researchers note that peatlands have played a significant role in regulating Earth's climate for millions of years, acting as important reservoirs of stored carbon even in a warmer world.
Source: Alfred Wegener Institute; Communications Earth & Environment, “Co-evolution of wildfires and early Sphagnum-peatlands near the Cretaceous South Pole”.