Model inter-comparison between statistical and dynamic model assessments of the long-term stability of blanket peat in Great Britain (1940–2099)

Abstract

We compared output from 3 dynamic process-based models (DMs: ECOSSE, MILLEN-NIA and the Durham Carbon Model) and 9 bioclimatic envelope models (BCEMs; including BBOG ensemble and PEATSTASH) ranging from simple threshold to semi-process-based models. Model simulations were run at 4 British peatland sites using historical climate data and climate projections under a medium (A1B) emissions scenario from the 11-RCM (regional climate model) ensemble underpinning UKCP09. The models showed that blanket peatlands are vulnerable to projected climate change; however, predictions varied between models as well as between sites. All BCEMs predicted a shift from presence to absence of a climate associated with blanket peat, where the sites with the lowest total annual precipitation were closest to the presence/absence threshold. DMs showed a more variable response. ECOSSE predicted a decline in net C sink and shift to net C source by the end of this century. The Durham Carbon Model predicted a smaller decline in the net C sink strength, but no shift to net C source. MILLENNIA predicted a slight overall increase in the net C sink. In contrast to the BCEM projections, the DMs predicted that the sites with coolest temperatures and greatest total annual precipitation showed the largest change in carbon sinks. In this model inter-comparison, the greatest variation in model output in response to climate change projections was not between the BCEMs and DMs but between the DMs themselves, because of different approaches to modelling soil organic matter pools and decomposition amongst other processes. The difference in the sign of the response has major implications for future climate feedbacks, climate policy and peatland management. Enhanced data collection, in particular monitoring peatland response to current change, would significantly improve model development and projections of future change.

Drivers of long-term variability in CO<sub>2</sub> net ecosystem exchange in a temperate peatland

“…-Annual NEE is positively correlated with the length of the growing season. (Dinsmore et al, 2009). The site was drained more than 100 years ago (Leith et al, 2014); the drains have become progressively less effective and re-vegetated over time, leading to slow and progressive rewetting of the site.…”

Restoration effects on water table depths and CO2 fluxes from climatically marginal blanket bog

“…As such it is important that 'intact' hydrological regimes are maintained/restored in at risk peatlands (e.g. Clark et al 2010a;Clark et al 2010b) to minimise the impacts of environmental change (Heathwaite 1993). While it should be noted that this study provides data from one blocked gully in 1 year and should be viewed only as a case-study only, these findings do also fit into an increasing body of evidence supporting the practice of gully-/drain-blocking for water-table re-establishment in peatlands (e.g.…”

Erosion in peatlands: Recent research progress and future directions

“…During the Medieval warm period between AD 950 and 1100, a decrease in rainfall and an increase in temperature resulted in drying of peat surfaces and promotion of erosion (Ellis and Tallis, 2001;Tallis, 1997). Bioclimatic modelling suggests a retreat of bioclimatic space suitable for blanket peatlands due to climatic change in the 21 st century (Clark et al, 2010;Gallego-Sala et al, 2010;Gallego-Sala and Prentice, 2013). Li et al (2017a) found that future climatic change will begin to affect sediment release from increasingly large areas of blanket peatland in the Northern Hemisphere.…”