Inconsistent Response of Arctic Permafrost Peatland Carbon Accumulation to Warm Climate Phases

Abstract

Northern peatlands have accumulated large carbon (C) stocks since the last deglaciation and during past millennia they have acted as important atmospheric C sinks. However, it is still poorly understood how northern peatlands in general and Arctic permafrost peatlands in particular will respond to future climate change. In this study, we present C accumulation reconstructions derived from 14 peat cores from four permafrost peatlands in northeast European Russia and Finnish Lapland. The main focus is on warm climate phases. We used regression analyses to test the importance of different environmental variables such as summer temperature, hydrology, and vegetation as drivers for nonautogenic C accumulation. We used modeling approaches to simulate potential decomposition patterns. The data show that our study sites have been persistent mid‐ to late‐Holocene C sinks with an average accumulation rate of 10.80–32.40 g C m−2 year−1. The warmer climate phase during the Holocene Thermal Maximum stimulated faster apparent C accumulation rates while the Medieval Climate Anomaly did not. Moreover, during the Little Ice Age, apparent C accumulation rates were controlled more by other factors than by cold climate per se. Although we could not identify any significant environmental factor that drove C accumulation, our data show that recent warming has increased C accumulation in some permafrost peatland sites. However, the synchronous slight decrease of C accumulation in other sites may be an alternative response of these peatlands to warming in the future. This would lead to a decrease in the C sequestration ability of permafrost peatlands overall.

Decreased carbon accumulation feedback driven by climate‐induced drying of two southern boreal bogs over recent centuries

“…However, due to the complexity of interactions between these factors and the highly heterogeneous nature of peatlands, links between peat carbon accumulation and any individual environmental variables are not straightforward (e.g. Loisel & Garneau, ; Piilo et al, ; Zhang, Gallego‐Sala, et al, ). We did not observe any changes in plant functional types, for example, from Sphagnum to shrubs (Tuittila et al, ); thus, we assume that the detected variation in CAR is largely due to variations in moisture and temperature, although changes within one plant functional type, for example, moss community, might alone could still drive changes in carbon accumulation due to different photosynthesis and decomposition rates at the species level (Hajek, Tuittila, Ilomets, & Laiho, ; Kangas et al, ; Laine, Juurola, Hajek, & Tuittila, ; Turetsky, Crow, Evans, Vitt, & Wieder, ).…”

“…Apparent CAR (ACAR; g C m −2 year −1 ) was calculated by multiplying the bulk density of a depth‐specific increment by its C content and by the accumulation rate. Peat decay modelling (Clymo, ) was used to derive the allogenic impact‐forced carbon accumulation variations (Zhang, Gallego‐Sala, et al, ). The Clymo model (1984) was first applied on the cumulative peat mass (bulk density) data to derive peat addition rate ( p ) and peat decay coefficient ( α ) using the curve fitting method.…”

Recent peat and carbon accumulation following the Little Ice Age in northwestern Québec, Canada

“…Our results indicated high accumulation rates during recent decades. Previous studies focussing on both the last millennium (Charman et al 2013, Garneau et al 2014, Loisel et al 2014 and recent decades (Zhang et al 2018b) showed that relatively high accumulation rates are likely caused by increased carbon inputs rather than by reduced decomposition. We acknowledge the difficulty of interpreting the recent peat accumulation rates due to the incomplete decomposition process and lower compaction of the surface peat and restraints on the chronologies.…”

Pathways for Ecological Change in Canadian High Arctic Wetlands Under Rapid Twentieth Century Warming

“…However, longer, warmer growing seasons and changes in Arctic precipitation regimes (Bintanja & Selten, ; Kattsov et al, ; Kopec et al, ) may stimulate carbon capture through enhanced plant productivity in peatlands and the transition of minerotrophic wetlands into organic peatlands (Charman et al, , ; Gallego‐Sala et al, ; Morris et al, ). Recent evidence shows an inconsistent response of Arctic and sub‐Arctic peatlands to warming in terms of carbon accumulation (Zhang, Gallego‐Sala, et al, ).…”