The consequences of the Little Ice Age period over peat sequestration in northern peatlands

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The research program presented in this 5-years proposal follows my precedent research activities conducted over the entire Holocene period providing original data on peat initiation, peatland development and related C accumulation from different ecoregions of the northeastern canadian boreal biome. Our results present regional spatial and temporal Holocene C accumulation along with distinct seasonal patterns and confirm the role of long-term climate variations as an important driver in peatland dynamics and related C sequestration. In the international community, recent initiatives have been taken up to enhance the understanding of critical climate periods on peat accumulation such as the Neoglacial period (3000 BP), the Medieval Climate Anomaly (350-1200 BP) and the Little Ice Age (LIA) (1350-1850 AD). In northern countries, the LIA represents a critical period as it has influenced permafrost aggradation over the past centuries. Nowadays, some relict permafrost remains in the most northern regions of the open boreal forest and in the taiga while geomorphic indices in some other part of the landscape suggests its recent melting. The detailed reconstruction of the onset of this recent cold anomaly period, its impact over peat accumulation and its recent disappearance influenced by the recent warming will be used as analogs to document the consequences of the present-day arctic warming in northeastern Canada. We intend to document the impacts of external forcings such as the variations in the North Atlantic Oscillation (NAO), solar radiation and/or volcanic activities that have been identified as principal causes of this cooling. Methods such as macrofossils, testate amoebae, humification and isotopic analyses coupled with precise dating chronologies (14C and 210Pb) and age models will support the detailed reconstructions of this period characterized by cold climate disturbance and subsequent warming. Results of improved methods will also be integrated into international efforts (Europe, United, other parts of Canada) for amalgamation of various peat databases and development of outputs that will be useful for the PMIP (Paleoclimate Modelling Intercomparison Project) and PCMIP (Paleocarbon Modelling Intercomparison Project) modellers community that respond to the IPPC reports.