Abstract

Peatland ecosystems are a small but persistent sink of carbon and currently store more than 600 Pg C globally. Peatlands preserve a stratigraphic record of net carbon accumulation, the net outcome of plant respiration and respiration. The rates of both these processes will increase with warming and an important question is which of these will dominate the overall response of the global peatland carbon sink to future climatic changes. In this seminar, I will present the results of a global study of changes in peatland carbon accumulation rates over the last millennium. This study explores the relationship between carbon accumulation rates over the last millennium and modern climate space. The results indicate that there is a positive relationship between carbon accumulation and photosynthetically active radiation for mid- to high-latitude peatlands in both hemispheres, i.e. carbon accumulation is lowest at high latitudes where PAR0 is lowest. However, this relationship reverses for sites at lower latitudes, suggesting that carbon accumulation is reduced under the warmest climate regimes. This is important because it highlights that there are limits to the predicted negative feedback of the peatland carbon sink to warming. I will additionally present modelled future projections under RCP2 .6 and RCP8 .5 scenarios to explain that the overall peatland negative feedback does not necessarily persist in time.