If carbon stocks are up, who gets the credit?

A practical method of distinguishing between human and natural factors.

Miko Kirschbaum1 & Annette Cowie2

[Miko Kirschbaum@csiro.au]CRC for Greenhouse Accounting, Australia

&1CSIRO Forestry and Forest Products, Canberra

2State Forests of NSW, Sydney

How does biospheric carbon exchange differ from fossil-fuel emissions?

Two key aspects:

Reversibility

Human control

Irreversibility of fossil-fuel emissions

Carbon stocks

Time (years)

Release

Reversibility ofbiospheric net emissions

Carbon stocks

Max -

Min -

Time (years)

Release

Sequester

Release

Full control of fossil-fuel emissions

Carbon stocks

Time (years)

Shared control ofbiospheric net emissions

Carbon stocks

Max -

Min -

Time (years)Human

Shared control ofbiospheric net emissions

Carbon stocks

Max -

Min -

Time (years)Human

Natural

Natural

Natural

Shared control ofbiospheric net emissions

Carbon stocks

Max -

Min -

Time (years)Human

Natural

Natural

Natural

Averagecarbon

The Marrakech Accord

“that accounting excludes removals resulting from:(a) elevated CO2 above pre-industrial

level; (b) indirect nitrogen deposition; &

(c) the dynamic effects of age structure resulting from activities and practices before 1990”

The Marrakech Accord

The aim: to distinguish between “direct human” and “other” factors

But it is very difficult to factor out the sum total of interacting “other” factors

Easier to factor out the “direct human” factor

Alternative C accounting

A - AverageC - CarbonS - Stocks

The ‘ACS’ scheme

Alternative C accounting

Total C stocks

0 10 20 30 40 50 60 700

50

100

150

200

250

Car

bo

n s

tock

s (t

C h

a-1)

A-g biomassC stocks

Years

Alternative C accounting

Kirschbaum et al. 2001

Total C stocks

ACS

0 10 20 30 40 50 60 700

50

100

150

200

250

Car

bo

n s

tock

s (t

C h

a-1)

A-g biomassC stocks

Years

Alternative C accounting

Kirschbaum et al. 2001

0 10 20 30 40 50 60 700

50

100

150

200

250

Car

bo

n s

tock

s (t

C h

a-1)

Years

Credit

Delayed crediting

Case studies

Canada

Kurz and Apps 1999

An

nu

al c

arb

on

flu

x(M

tC y

r-1)

-100

0

100

200

300

1920 1930 1940 1950 1960 1970 1980 1990

-100

0

100

200

Biomass

DOM

Total

Relative to

199

0fo

ssil fu

el (%

)

Canada

Kurz and Apps 1999

0

1

2

3

4

5

6

1920 1930 1940 1950 1960 1970 1980 1990

Are

a d

istu

rbe

d (

Mh

a)

Insects Harvesting Total Fire

0

1

2

3

4

5

6

1920 1930 1940 1950 1960 1970 1980 1990

Are

a d

istu

rbe

d (

Mh

a)

Insects Harvesting Total Fire

An

nu

al c

arb

on

flu

x(M

tC y

r-1)

-100

0

100

200

300

1920 1930 1940 1950 1960 1970 1980 1990

-100

0

100

200

Biomass

DOM

Total

Relative to

1990

foss

il fue

l (%)

No land-use change

Carbon credit for creating national parks

Debit/credit for management changes that affect

average carbon stocks

USA

Birdsey and Heath 1995

0

5

10

15

20

1960 1970 1980 1990 2000

An

nu

al c

arb

on

flu

x(M

tC y

r-1)

0

50

100

150

200

250

Biomass

DOM

Total Re

lative to

19

90

fos

sil fue

ls (%)

Land abandonment is a land-use change,

but occurred before 1990

Further land abandonmentis eligible

New Zealand (1990)

Maclaren 1996

0

50000

100000

150000

200000

250000

300000

5 10 15 20 25 30 35 40 50 60 80

Age Class

Are

a (h

a)

Ford-Robertson, pers. comm.

-50

0

50

100

1990 2000 2010 2020

C s

tock

s (M

tC)

100

200

300

Post 1990

Relative to

1990fo

ssil fuels (%

)

Replanted pre 1990Original

pre 1990

1990 2000 2010 2020

C f

lux

(MtC

yr-1

)

-5

0

5

10

Total estate

Pre 1990 plantations

Pre-1990 plantations donot count

Post-1990 plantations count if the ramp-up is not yet completed

Australia

•Production forests

•Plantations

•Land clearing

•Vegetation thickening

Australia

•Production forests

•Plantations

•Land clearing

•Vegetation thickening

as for Canada

as for New Zealand

Land clearing

•Clearing virgin forest

• Clearing previously cleared land (with land-use change)

•Cyclical re-clearing

NCAS 2002

1990 1995 2000

Ca

rbo

n f

lux

(M

tC y

r-1)

0

10

20

30

1990 1995 2000

Are

a c

lea

red

('

00

0 h

a y

r-1)

100

200

300

400

Converted

Relative to

1990fo

ssil fuels (%

)

Recleared

0

20

40

Areas subject toland-use change, or

intensification of land use, are counted

Areas just re-cleared have no land-use change

and are not counted

Vegetation thickening

Burrows et al. 2002

Stand biomass (tC ha-1)

0 20 40 60

Bio

ma

ss in

cre

me

nt

(tC

ha-1

yr-1

)

0.0

0.5

1.0

1.5Growth rate:

1.9% yr-1

Changed burning regimeand grazing animals are

land-use changes,but occurred before 1990.

Biospheric carbon storage

Is reversible

Summary

Only partly under human control

The ACS scheme is a practical way to factors out

the human component

Thank you!