Accounting for terrestrial ecosystem feedbacksin a regional climate model
Baltex 2008: Utility of Regional Climate Models
Ben Smith
Geobiosphere Science Centre,Lund University, Sweden
Credits:
Patrick Samuelsson, Ulf Hansson, Rossby Centre SMHI
Anna Wramneby, Lund University
Global carbon cyclemean stocks and fluxes for 1990s (Gt C)
oceans:38 000 +2/yr
soils: 1700
vegetation:600
atmosphere: 760 +3/yr
terrestrial ecosystems:2 300 +3/yrland use
change
fossil fuel burningcement production
92
90
8
6 2
120
123
Source: IPCC, 2007
Albedo change could offset carbon sequestrationas forests expand at high northern latitudes*
*Betts 2000Nature 408: 187
Albedo change
Radiation forcing due to albedo change
W m−2
CO2-emission yielding same radiation forcing
tC ha−1
latent heat(evapo-
transpiration)sensible
heat
sensibleheat
incomingSW radiation
incomingSW radiation
Partitioning of land surface-atmosphere energy fluxesdepends on vegetation type and cover
latent heat(evapo-
transpiration)
Land surface scheme of RCA3*
• forest, open land, bare ground, snow
• conifer, broadleaved forest (prescribed fractions)
• leaf phenology (prescribed)• leaf area index (scaled to
soil T)
*Samuelsson et al. 2006Nature 408: 187
Soil organicmatter
SOM dynamics
populationdynamics
migrationphenology& growth
Vegetation
climateCO2
LPJ-GUESS – a process-based ecosystem modelling framework*
*Smith et al. 2001Global Ecology and Biogeography 10: 621
0
5
10
15
20
0
5
10
15
20Model Model
Bio
mas
s (k
gC m
−2)
0
4
8
12
16
0
4
8
12
16Pollen record Pollen recordP
olle
n ac
cum
ulat
ion
rate
Years before present Years before present200040006000800010,000 0 200040006000800010,000 0
Pinus sylvestrisPicea abiesPopulus tremula
Betula spp.Alnus incanaUlmus glabra
Quercus roburTilia cordataCorylus avellana
*Miller et al. 2008Journal of Ecology
Aborrtjärnen, Sweden 63° 53’ N Laihalampi, Finland 61° 29’ N
Modelling Holocene vegetation history in Fennoscandia*
Observed and modelled changes in leaf phenology and LAI*
*Lucht et al. 2002.Science 296: 1687-1689
Global land areasnorth of 40°N
0.100.05
0−0.05−0.10−0.15
0.100.05
0−0.05−0.10−0.15
1996 1997 1998 1996 1997 1998
Net
eco
syst
em C
exc
hang
e (k
gC m
−2m
o−1 )
Temperate deciduous(Denmark 55° 29’ N, 11° 39’ E)
Boreal conifer(Finland 61° 51’ N, 24° 17’ E)
Temperate conifer(Scotland 56° 36’ N, 3° 48’ W)
Mediterranean conifer(France 44° 43’ N, 0° 05’ E)
eddy covariance datacohort modelpopulation model
flux to atmosphereflux to ecosystem
Carbon exchange of European forest ecosystems*
*Morales et al. 2005Global Change Biology 11: 2211
boundarylayer
vegetation
soilwater
snow
ecosystem model
boundarylayer
vegetation
soilwater
snow
land surface scheme rest of RCM
climate and weatherclimate and weather climate andweather
RCA-GUESS: a coupled regional climate-terrestrial vegetation model
soil carbon
fraction of conifer,broadleaved forest,open land, bare ground
roughness, albedo,displacement heightevaporation,transpiration
incoming SW radiation photosynthesis,stomatal conductance
interception, displacement height, radiation partitioning,transpiration
near-canopytemperature
respiration,photosynthesis,canopy conductance,fire
soil water stomatal conductance,soil respiration,fire
soil temperature
GUESS tells RCA Used by RCA for RCA tells GUESS Used by GUESS for
respiration
leaf area index(LAI)
Surface temperature (°C) Precipitation (mm mo−1) Cloudiness (%)
RCA3-GUESS − CRU RCA3-GUESS − ERA40 RCA3-GUESS − CRU
RCA3-GUESS ERA40 1961-1990 JJA
Comparison of modelled to observed climate
RCA3-GUESS Ver 070709
Leaf
are
a in
dex
2021-291961-902021-291961-90
RCA3-GUESS
RCA3
Change in JJA leaf area index ΔLAI
Simulated change (2020-2029)−(1961-1990) RCA3-GUESS ECHAM5-A1B Transient
Simulated changes in vegetation structure
Leaf
are
a in
dex
boreal/temperate needleleaved evergreenshade-tolerant broadleaved summergreenshade-intolerant broadleaved summergreenbroadleaved evergreenMediterranean needleleaved summergreengrass/herbaceous vegetation
trees
S Sweden Alps W Turkey
Simulated changes in vegetation composition
RCA3-GUESS ECHAM5-A1B Transient 1964-2030Forest tile
Temperature change JJA ΔT Precipitation change JJA ΔP
Feedback contribution ΔTRCAG−ΔTRCA Feedback contribution ΔPRCAG−ΔPRCA
°C mm mo−1
Quantifying feedback of vegetation structural change on climate
Simulated change (2020-2029)−(1961-1990) RCA3-GUESS ECHAM5-A1B Transient
sequestration emission
Net ecosystem C exchange (kgC m−2 yr−1)
1964-1990 2021-2030
RCA3-GUESS ECHAM5-A1B Transient 1964-2030Open land tile
Simulated change in terrestrial ecosystem carbon balance
Future prospects
• Centennial runs, stabilisation scenario, alternative emission pathways
• Land use change and management (forestry, agriculture)
• Peatlands, permafrost, non-CO2 trace gases
• Integration with global studies using ESMs
Thanks
Rossby Centre at SMHI
The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS)
The Swedish Research Council