Current climate warming alters the overall water balance by changing the spatial patterns of evapotranspiration and redistribution of precipitation, modulating droughts in continental interior. These climate changes have a significant effect on natural fire regimes and modify the functioning of boreal ecosystems where fire plays an important role in soil dynamics, the regeneration processes of many plant species, and the global carbon balance. The consequences of current global warming on the risk of fire are real and all projections indicate an increase of fire activity in the coming decades within the boreal forest. During the last years, our international network has developed interdisciplinary research projects to understand the functioning of the boreal forest (Canada, Scandinavia & Russia) during the Holocene (last 11,700 years). We analyze various proxies (charcoal, plant macroremains, pollen, chironomids, biogeochemistry) trapped in lacustrine and peat sediments to reconstruct fire histories, vegetation dynamics and climate conditions in order to characterize the natural variability of fire disturbance regimes and the consequences on forest dynamics under changing climate conditions. Our studies aim to inform sustainable forest management practices that preserve the natural processes and biodiversity of boreal ecosystems.