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This paper provides information on the impact of recent climate change on carbon sequestration in peatland systems in South West England. This is important because peatlands have the potential to sequester and hold large quantities of ant hropogenically released CO2. This paper investigates whether there has been a reduction in the strength of carbon sinks in a valley mire and blanket bog, which occur on the limits of the biogeographical envelop for peallands in Britain. Past rates of carbon accumulation were calculated from peat depth and the sequential analysis of peat age, bulk density and carbon content from cores taken from valley mire and blanket bog. At the valley mire site contemporary net ecosystem carbon balance (NECB) was calculated by measuring inputs to the peat body, via net primary productivity (NPP), of Sphagna. Losses of C from the peat body were calculated by measuring CH4, and aquatic carbon, calculated from catchment export of particulate and dissolved organic carbon. The study found similar mean rates of carbon accumulation since 1850 of 11.26 t +/- 0.68 t CO(2)e ha(-1) yr(-1) (307 g C m(-2) yr(-1)) in valley mire and 11.77 t +/- 0.88 t CO(2)e ha(-1)yr(-1) (321 g C m(-2) yr(-1)) in blanket bog. The mean present-day CO2 sequestration rate for Sphagna on valley mire was calculated to be 9.13 t +/- 0.98 t CO(2)e ha(-1) yr(-1) (249 g C m(-2) yr(-1)). Both past and contemporary rates of CO2 sequestration were found to be at the maxima of those reported for temperate peatlands. NPP was found to vary according to microform with higher rates of carbon sequestration found in lawn and hummock microforms compared with pools. Our work suggests that recent changes in the climate appear to have had limited impact on the strength of peatland carbon sinks in South West England. (C) 2019 Elsevier B.V. All rights reserved.