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One hundred and fifty years of peatland carbon sequestration in southwest England

03 Mar 2021 | Science Notes

From CO2Science: Contrary to model projections, data from two locations indicate stable (or possibly increasing) carbon sequestration rates in UK peatland.

Paper reviewed: Lunt, P.H., Fyfe, R.M. and Tappin, A.D. 2019. Role of recent climate change on carbon sequestration in peatland systems. Science of the Total Environment 667: 348-358.

In the words of Lunt et al. (2019), “many authors working with global climate models propose that there may be a decline in the strength of high latitude and tropical peatland carbon sinks throughout the 21st century” in response to projected changes in precipitation and temperature. And focusing on the region of the United Kingdom (UK) they add “it has been suggested that future climatic changes will result in a contraction of the distribution of active blanket bog in the UK towards the north and west, and outside this distribution peatlands may cease active growth,” citing the works of Gallego-Sala et al. (2010) and Gallego-Sala and Prentice (2013). Consequently, this team of three researchers says “an understanding of recent changes in rates of carbon sequestration in regions such as southwest England, indicated as marginal to growth, is therefore vital to our understanding of how sensitive these peatlands are to present and future climate change.” And so it was that the scientists proceeded to conduct an analysis of historical carbon sequestration on two peatlands in this region, Fox Tor Mire (a valley mire; 50.517°N, 03.956°W) and Red Lake Mire (a precipitation-only ombrotrophic blanket bog; 50.488°N, 03.910°W).

The results of the study indicated that since 1850, peat accumulation rates averaged 9.5 mm per year at Fox Tor and 6.62 mm per year at Red Lake, which rates according to Lunt et al. “far exceed the average historical rates described for more northerly, boreal and continental peatlands.” Similarly, carbon accumulation rates during this period were also high (307 and 321 g C m-2 yr-1 for Fox Tor and Red Lake, respectively), which are reportedly “at the upper limits of those recorded [elsewhere].”

Speaking about these findings, Lunt et al. say they demonstrate “recent changes in climate [since 1850] appear to have had no impact on the strength of peatland carbon sinks in southwest England.” And given the fact that past and current carbon sink strength of these peatlands are “at the upper limits of those reported in the literature for temperate peatlands”, they opine it suggests “recent bioclimatic envelope models may underestimate the potential future contribution that UK peatlands can make to carbon sequestration under observed climate trends.” Consequently, the four researchers conclude “contrary to expectations based on bioclimatic envelope models, peatland carbon sequestration rates in southwest England are stable and possibly increasing.”

Gallego-Sala, A.V. and Prentice, I.C. 2013. Blanket peat biome endangered by climate change. Nature Climate Change 3: 152-155.

Gallego-Sala, A.V., Clark, J.M., House, J.I., Orr, H.G., Prentice, I.C., Smith, P., Farewell, T. and Chapman, S.J. 2010. Bioclimatic envelope model of climate change impacts on blanket peat distribution in Great Britain. Climate Research 45: 151-162.

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