Researchers at Lund University have discovered evidence of climate change by analyzing decades-old military air samples, showing moss spores release weeks earlier than in the 1990s. The study highlights how warmer autumns from previous years drive these changes more than current spring conditions. This approach offers a new way to track ecological responses over time.
In a surprising use of historical military data, scientists from Lund University in Sweden examined air samples collected by the Swedish Armed Forces since the 1960s. Originally gathered to monitor radioactive fallout from nuclear weapons testing, these samples used glass fiber filters that inadvertently preserved DNA from airborne biological particles like pollen and spores. Per Stenberg, a researcher at Umeå University, identified this archive's potential for ecological study.
The team focused on 16 moss species and groups, tracking spore dispersal over 35 years. Their findings, published in the Journal of Ecology, indicate that mosses now start releasing spores about four weeks earlier than in 1990, with the peak arriving roughly six weeks sooner. "It's a considerable difference, especially considering that summer is so short in the north," noted Nils Cronberg, a botany researcher at Lund University.
Warmer autumn temperatures appear to be the main driver, allowing mosses extra time to develop spore capsules before winter. Unexpectedly, factors like snow thaw or spring air temperatures in the dispersal year had little influence. "We had expected that snow thaw or air temperature in the same year as spore dispersal would be crucial, but climate conditions the year before were shown to be the most important factor," said Fia Bengtsson, formerly at Lund University and now at the Norwegian Institute for Nature Research.
This DNA-based method could extend to other wind-dispersed species, enabling comparisons of ecological changes across Sweden from north to south since the 1970s. Cronberg anticipates the results will contribute to the next Intergovernmental Panel on Climate Change report on climate effects.
