Contribution of disturbance to increasing seasonal amplitude of atmospheric CO2

Recent increases in the seasonal amplitude of atmospheric carbon dioxide (C O2) at high latitudes suggest a widespread biospheric response to high-lati tude warming. The seasonal amplitude of net ecosystem carbon exchange by no rthern Siberian ecosystems is shown to be greater in disturbed than undistu rbed sites, due to increased summer influx and increased winter efflux. Inc reased disturbance could therefore contribute significantly to the amplifie d seasonal cycle of atmospheric carbon dioxide at high latitudes. Warm temp eratures reduced summer carbon influx, suggesting that high-latitude warmin g, if it occurred, would be unlikely to increase seasonal amplitude of carb on exchange.