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Quantification of peatland-mediated feedbacks to
the climate system
Nitin Chaudhary, etal.
Department of Geosciences, University of Oslo and
Department of Physical Geography and Ecosystem Science, Lund University
Introduction
Peatlands are one of the biggest carbon reserves
on terrestrial ecosystems mostly located in
northern latitude areas (45–75°N). They have
sequestered approximately 300-550 PgC since the
Holocene [1]. The majority of northern peatland
areas coincide with low altitude permafrost [2]. The
recent changes in climate and land use patterns
have disturbed the Earth’s climate-carbon cycle
equilibrium. These changes trigger some
potentially important land-surface feedbacks, which
will further modify the Earth’s climate[3]. The
ongoing changes in peatland carbon balance as a
result of climate warming have the potential for
strong positive and negative feedbacks to climate,
but these impacts are poorly constrained. The
main aim of this project is to make a step change
in our understanding of peatland-mediated
feedbacks and their impacts on climate and the C
cycle. This project also seeks to enhance our
knowledge about the processes controlling
peatland responses to climate change and the
effects of land-atmosphere interactions on the
overall behaviour of the Earth system.
The specific objectives of this study are:
a) To integrate a well-benchmarked process-based
methane (CH4) biogeochemical scheme
b) b) To understand the role of peatland-mediated
feedbacks on climate
c) c) To perform recent past, present and future
simulations in order to capture the impacts of
peatland-mediated feedbacks on regional
climate
Peatland-Vegetation Model
Recent Findings
Figure 2. a) Carbon accumulation rates (average
1990–2000), b) under RCP2.6 scenario (average
2091–2100), c) under RCP8.5 scenario (average
2091–2100), d) clipped carbon accumulation rates
(average 1990–2000) according to the most up-to-
date observed map, e) difference between images B
and A; and f) difference between images C and A
LPJ-GUESS Peatland
LPJ-GUESS is a modular framework to explicitly
model physiological, and biogeochemical
processes governing the growth and competition
of woody-plant individuals [4]. We combined a
dynamic multi-layer approach to peat formation
and composition [5] with soil freezing-thawing
dynamics [2], plant physiology and competition
among plant functional types (PFTs) - shrubs,
graminoids and mosses.
References
1) This study will provide a better understanding of
the role of peatland-mediated feedbacks and
peatland processes at regional and global scales
by including their representations in regional and
global ESMs.
2) The study results can be used to predict the
most probable demarcation of peatland and
permafrost extent for the coming century and to
reduce current uncertainties regarding
CH4emissions from the peatlands.
3) The study will help in identifying the ‘hotspots’ in
the pan-Arctic region and other geographical
areas that are vulnerable to high C emissions and
permafrost degradation and will evaluate their
direct consequences to plant ecology and
hydrology.
Expected Results
Figure 1. Schematic representation of LPJ-GUESS-
Peatland. Dynamic peat layers deposit above the
static mineral soil layers (0.5+1.5m).In the shallow
peat, plant roots are present in both mineral and peat
layers. Once the peat become sufficiently thick (2m),
all roots exist in the peat soil.
Carbon accumulation rates
Future Development
[1] Gorham E. 1991. Northern peatlands - role in the carbon-cycle and
probable responses to climatic warming. Ecological Applications 1:182-195.
[2] Wania R, Ross I, Prentice IC.2009a. Integrating peatlands and
permafrost into a dynamic global vegetation model: 1. Evaluation and
sensitivity of physical land surface processes. Global Biogeochemical Cycles
23. [3] IPCC. 2013. Climate Change 2013: The Physical Science Basis.
Contribution of Working Group I to the Fifth Assessment Report of the
Intergovernmental Panel on Climate Change (art.16):NY, USA. [4] Smith, B.,
Prentice, I. C., Sykes, M. T., 2001. Representation of vegetation dynamics in
the modeling of terrestrial ecosystems: comparing two contrasting
approaches within European climate space. Global Ecology Biogeography
10,621-637 [5] Frolking S, etal.. 2010. A new model of Holocene peatland
net primary production, decomposition, water balance, and peat
accumulation. Earth System Dynamics 1, 1-21.[6] Wramneby, A., et al.
Geophys. Res.-Atmos. 115,. [7] Smith, B., et al. Tellus Ser. A-Dyn. Meteorol.
Oceanol. 63,87-106, [8] Chaudhary, N.. (2020), Modelling past and future
peatland carbon dynamics across the pan‐Arctic. Glob Change Biol.
Figure 4. A proposed schematic representation of
regional Earth system model, RCA-GUESS
In our recent study[8] using our peatland-
vegetation model, we found that areas where peat
production was initially hampered by permafrost
and low productivity would accumulate more
carbon because of the initial warming, moisture
rich environment due to permafrost thaw, higher
precipitation and elevated CO2levels. On the
other hand, areas which experience reduced
precipitation rates and without permafrost will lose
more carbon in the near future, particularly,
peatlands located in the European region and
between 45–55°N latitude.
Feedbacks are important interactions in the Earth
system which can accentuate or dampen the
effects of climate forcings and play an important
role in determining the future climate state.
Changes in the land surface properties such as
albedo, surface roughness, soil moisture, leaf
area and rooting depth directly modify the surface
energy, momentum and moisture fluxes which in
turn trigger biogeophysical feedbacks[6]. These
feedbacks are critical for regional climate and can
be captured using regional ESMs. By studying
these feedbacks, the relevant information related
to the direction, strength, and magnitude of these
triggers can be extracted. To accurately quantify
and predict the effects of these feedbacks, state-
of-the-art regional ESMs need to be employed.
However, due to the absence of any
comprehensive ESMs with the representation of
detailed peatland and cryospheric processes, our
understanding of the peatland-mediated
feedbacks at regional and global scales is limited.
My individual–and patch–based peatland-
vegetation model (LPJ-GUESS) can capture the
C accumulation rates and permafrost dynamics at
different spatial and temporal scales and will be
further improved to account for these changes.
This research project focuses on further
development and evaluation of an established
peatland version of the LPJ-GUESS, a dynamic
global vegetation model[4]. The improved and
adapted peatland-vegetation model will be
coupled with the regional ESM, RCA-GUESS, a
regional Earth System Model (ESM) [7].
RCA-GUESS is one of the comprehensive
regional ESMs which uses an interactive coupling
between LPJ-GUESS and the Land Surface
Scheme of RCA (see Fig. 4). The model
comprises two sub-models: a vegetation sub-
model based on LPJ-GUESS and the physical
sub-model RCA. The vegetation sub-model
simulates vegetation dynamics and leaf phenology
while the physical sub-model simulates regional
climate conditions.
Integrating peatland dynamics
in Regional ESM –RCA-GUES
Bio-geophysical feedbacks
Figure 3. Probable changes in dominant vegetation
cover in the northern latitude region - a) 2000 and b)
2100 (RCP8.5)
b)