NEW PALEOCLIMATE RECORDS FROM THE RUSSIAN FAR EAST: CARBON ACCUMULATION RATES AND ECOLOGICAL CHANGE OVER THE LAST 11,000 YEARS FROM WESTERN KAMCHATKA

Northern high latitudes are changing rapidly in response to climate warming. These regions in turn affect the rate of global change by altering large-scale atmospheric circulation and surface-atmosphere carbon fluxes. Numerous high latitude paleoclimate reconstructions have improved our understanding of past climate change in the Northern Hemisphere, but high-quality terrestrial paleoclimate records from the Russian Far East are scarce. This region is located at a unique intersection of the North Pacific, Siberian, and Arctic climatic influences and has extensive peatland areas, a potentially important and poorly documented land carbon hotspot. Here we present high-resolution carbon accumulation and other paleoecological records covering the last 11,000 years from peat cores collected on the Kamchatka Peninsula. This is the first carbon accumulation study in this region.

Our two study sites are bogs on the western lowlands of Kamchatka along the Sea of Okhotsk. Site KAM12-C4 (54.02 N, 156.13 E) is located 18 km from the coast at 91 m elevation, while site KAM12-C1 (54.91 N, 156.60 E) is 62 km from the coast at 256 m elevation. Cores C1 and C4 are 450 and 375 cm in length, respectively. Initial chronologies are based on radiocarbon dating of bulk organic material and Sphagnum plant macrofossils.

At both sites, peat deposition began at 11 ka (thousands of calendar years before present), is continuous to the surface, and interlayered with tephra. We measured bulk density and organic matter content at 1 cm intervals. The results show similar mean bulk densities of 0.1 g cm³. However, the cores show two periods of centennial-scale divergence, with C1 dropping to 0.06-0.08 g cm³ and C4 rising to 0.14-0.16 g cm³, centered on 7.2 and 5.3 ka. Similarly, both sites show millennial-scale divergence between 4.5 and 2.1 kaa with 0.06 g cm³ in C1 and 0.19 g cm³ in C4. Pollen analysis for C4 shows a rise in tree pollen between 5.7 and 4.4 ka, particularly from Betula ermanii (stone birch) and Betula platyphylla (white birch). Coincident divergence in the records suggests differing responses to a common environmental forcing, potentially associated with proximity to the ocean or elevation. Comparison between these sites may have important implications for regional atmospheric circulation and ocean current dynamics during the Holocene.