Regional trends in the land carbon cycle and the underlying mechanisms over the period, 1980-2009 S....

Regional trends in the land carbon cycle and the underlying mechanisms

over the period, 1980-2009 

S. Sitch, P. Friedlingstein, G. Bonan, P. Canadell, P. Ciais, P.M. Cox, P. Foster, E. Gloor, K. Goldewijk, C. Huntingford, G. Hurtt, C. D. Jones, S. Piao, I.C. Prentice, C. Le Quere, P. Levy, M. R. Lomas, L. Mercado, B.

Mueller, M. Reichstein, S. Running, S. I. Seneviratne, E. Shevliakova, P. Thornton, N. Viovy , G. van der Werf, F. I. Woodward, S. Zaehle, M. Zhao

Photosynthesis

CO2

Plant respiration

CO2

CO2

Soil respiration

(heterotrophic)

RH

Net ecosystem exchange NEE

Terminology

Net Primary productivity (NPP)=

GPP-Plant respiration

RH - NPP

Gross Primary productivity (GPP)=

Photosynthesis +leaf respiration

Total CO2 emissions

Atmosphere

Data: NOAA, CDIAC; Le Quéré et al. 2009, Nature-geoscience

CO2 P

artit

ioni

ng (P

gC y

-1)

1960 20101970 1990 20001980

10

8

6

4

2

Key Diagnostic of the Carbon CycleEvolution of the fraction of total emissions that remain in the atmosphere

Fate of Anthropogenic CO2 Emissions (2000-2008)

Le Quéré et al. 2009, Nature-geoscience; Canadell et al. 2007, PNAS, updated

1.4 PgC y-1

+7.7 PgC y-1

3.0 PgC y-1

29%

4.1 PgC y-1

45%

26%2.3 PgC y-1

Modelled Natural CO2 Sinks

Le Quéré et al. 2009, Nature-geoscience

Global Annual Budget Regional Trends in Land C-Sinks (Trendy)Compare DGVM-based estimates with other

evidence- Satellite derived data

- Fluxtower data

- Atmospheric Monitoring Stations

Regional Trends in C-sinks and Annual Global Budget

GCP- Land trends: modelling protocol Contact: Stephen Sitch (s.sitch@leeds.ac.uk) & Pierre Friedlingstein (pierre.friedlingstein@bristol.ac.uk)Goal: To investigate the trends in NEE over the period 1980-2009

Participating modelsJULES, LPX, ORCHIDEE, O-CN, HyLand, SDGVM, NCAR CLM4, GFDL/Princeton

Model simulationsThe models will be forced over the 1860-2009 period with changing CO2, climate (CRU/NCEP)

and land use:

S1: CO2 onlyS2: CO2 and climateS3 (optional): CO2, climate and land use

Trendy Protocol

Land Source trend

positive NPP trend < positive RESP trend

negative NPP trend < negative RESP trend

negative NPP trend, positive RESP trend

Land Sink trend

positive NPP trend > positive RESP trend

negative NPP trend > negative RESP trend

positive NPP trend, negative RESP trend

Trends in Land Processes

Land Sink trend

positive NPP trend > positive RESP trend

negative NPP trend > negative RESP trend

positive NPP trend, negative RESP trend

Land Source trend

positive NPP trend < positive RESP trend

negative NPP trend < negative RESP trend

negative NPP trend, positive RESP trend

Climatic Drivers of Trends in Land Processes

B. Mueller, ETH Zurich

Satellite Evidence: Trends in Soil Moisture

0.95

1

1.05

1.1

1.15

1.2

1.25

1.3

1.35

1900 1920 1940 1960 1980 2000

Frac

tion

al N

PP C

hang

e

Year

TRIF FNPP

LPJ FNPP

SDGVM FNPP

Remarkable Similarity between NPP evolution from DGVMs

Global NPP explains most of the NEE variability

DGVM sink vs MODIS-NPP)

M Zhao

Alternative Upscaling Approaches Multidimensional flux patterns...

0 2000LE [MJ m-2 yr-1]

0

2000

H [

MJ

m-2

yr-

1]

Color: GPP

... models to be cross-evaluated against.Reichstein

remote sensingof CO2

Tem

pora

l sc

ale

Spatial scale [km]

hour

day

week

month

year

decade

century

local 0.1 1 10 100 1000 10 000 global

forestinventory

plot

Countries EUplot/site

talltowerobser-

vatories

Forest/soil inventories

Eddycovariance

towers

Landsurface remote sensing

JJA

Stippled areas > 90% of the models agree in the sign of the change

http://www.ipcc.ch/

Future Precipitation Changes (Summer Droughts?)

Use set-up to produce global/regional annual C-budgetsDrought may be an important driver of the present-day

trends in the land carbon cycleClimate Models Project Summer Drought in Continental

RegionsDrought may be an important driver of the future trends

in the land carbon cycleCritical to understand Ecosystem Response to Drought

for future Earth System feedbacks

Summary