Monsoon-driven teleconnections between Holocene fire activity in Central Asian and Neotropical ecosystems

Fires play an important role in the climate system. The boreal forests in Southern Siberia and the Neotropics are crucial regions for global fire emissions with only few available paleofire records. High-alpine ice archives such as Tsambagarav glacier in the Mongolian Altai and Illimani glacier in the Bolivian Andes located close to boreal and evergreen forest ecotones, respectively, are suitable to understand large-scale fire activity in these ecosystems. We discuss strong similarities between the Mongolian Altai and Neotropical ice core paleofire records with declining fire activity during the Late Holocene and hypothesize teleconnections between regional fire activity, possibly due to shared climate drivers in the Northern and Southern hemisphere. Well-documented records of South American summer monsoon activity over the Holocene show a consistent strengthening towards the Late Holocene. The related southwards shift of the Intertropical Convergence Zone resulted in increased monsoonal precipitation that reduced flammability of evergreen vegetation. In contrast, Asian paleo records suggest gradually weakening monsoon activity towards the Late Holocene that resulted in regionally drier conditions. These climate trends induced retractions of boreal forests in the Mongolian Altai, thus limiting fuel availability and fire incidence. We conclude that the main driver of fire activity in these two ecosystems was not temperature, but rather monsoonal-driven moisture. More data are needed to confirm our hypothesis on monsoon-driven teleconnections between regional fire activity.